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Aspberger's Disorder and Violence: A Review
On 12/14/12, the mass murder of 20
elementary school children and 6 adults in
Newtown, CT, by someone widely reported
to have Asperger’s disorder led to
increasing questions about the association
between this condition and violent
behavior.
These questions have led to valid concerns from advocacy organizations and families
of people with Asperger’s disorder and related conditions (e.g., autism) that people
with these conditions will be stigmatized as violent or as future mass murderers,
particularly given the widespread media coverage. As has been correctly noted in the
media, people with Asperger’s disorder are already stigmatized based on the nature of
their condition and are more likely to be the victims of aggression than the aggressor.
It is also correctly to say that there is no epidemiological scientific research linking
Asperger’s disorder to planned acts of committed violence. However, it is incorrect to
state that there is no association at all between Asperger's disorder and violence.
FEATURED BOOK: The Complete Guide To Asperger's Syndrome
As a board certified neuropsychologist, I have followed this topic in the media closely,
both on television and in print. In doing so, I have heard and read many statements
about what “the studies” show (or don’t show) about Asperger’s disorder and violence.
However, I have rarely seen or heard a reference to a specific research study.
The purpose of this article is to provide the reader with the most detailed and extensive objective review
of the peer-reviewed scientific literature on Asperger’s disorder and violent behavior. This is followed by
my own conclusions on what these studies show, citation information for this article, and a reference list.
Historical Background:
Examples of the latter include pre-occupation with one or more stereotyped and restricted patterns of
interest that is abnormal in intensity or focus, inflexible adherence to specific non-functional rules or
rituals, stereotyped and repetitive motor mannerisms (e.g., hand flapping), and preoccupation with parts
of objects. Essentially, Asperger’s disorder is autism without additional impairments in communication
abilities (such as significant delay in or lack of spoken language). While it is true that the diagnostic
criteria for Asperger's disorder does not include violence, this is not sufficient evidence to deny a
possible association. Determining if such an association exists requires looking beyond the diagnostic
criteria and reviewing the scientific literature.
The diagnostic criteria for Asperger’s disorder are found in the Diagnostic and Statistical Manual of
Mental Disorders - 4th edition (DSM-IV). Similar criteria also exist in the Internal Classification of
Diseases (ICD) manual. People with Asperger’s disorder are more prone to develop other forms of
mental health disorders such as depressive disorders, anxiety disorders, schizophrenia (Allen et al,
2008), bipolar disorder, and personality disorders. Whether or not Asperger’s disorder and other
disorders listed in DSM-IV with a strong neurological basis should be classified as a “mental disorder”
is a controversial topic that is discussed in the introduction of the DSM-IV. Advocacy groups generally
do not like the term “mental disorder” being applied to people with Asperger’s disorder and related
conditions, but it is often described as a mental disorder such in the research literature. In this writer’s
opinion, the condition would be best described as a neuropsychological disorder.
In 1944, Dr. Hans Asperger, a Viennese child psychiatrist, initially described signs of the condition that
later came to bear his name in four boys. The study was entitled “Autistic Psychopathy in the Child”
and was translated into English in the book Autism and Asperger Syndrome by Uta Frith in 1991.
Interestingly, application of DSM-IV criteria to Hans Asperger’s four cases has shown that they would
actually be classified today as autistic (Miller & Ozonoff, 1977). For this reason, any violent behavior
described in those cases (such as the boy, Fritz V) will not be discussed further here because the
purpose of this article is to focus on cases that would meet modern criteria for Asperger’s disorder.
However, it is noted that researchers later located 177 patients who were followed in Hans Asperger’s
clinic in Austria and found that the average percentage of registered convictions was similar to that of
the general male population over the studied time period (Hippler et al, 2010). However, the problem
with this study is that the author previously reviewed Dr. Asperger’s files and found that 32% did not
meet modern day criteria for Asperger’s disorder (Hippler & Klicpera, 2003).
Hans Asperger’s work was initially brought to the attention of English readers by Van Krevelen &
Kuipers (1962) and by Van Krevelen (1971). Van Krevelin (1971) noted that people with the condition
lacked “understanding of, and interaction with other people’s feelings.” Modern day interest in
Asperger’s disorder (referred to as Aspergers from this point forwards) began with an English
publication by Lorna Wing in 1981, in which she slightly changed and expanded Hans Asperger’s
original description. This paper brought significant attention to the condition and placed it on a spectrum
of autistic disorders.
Wing (1981) noted that 4 of her 34 cases (12%) had “a history of rather bizarre antisocial acts,
perhaps because of their lack of empathy.” (Of note, modern day research suggests that not all
children with Aspergers lack empathy but that they often have deficits in empathy or poor empathy).
One of the boys discussed by Wing (1981) reportedly injured another student in the course of
experimenting with the properties of chemicals. While most patients with Aspergers do not present
with antisocial behavior, Wing noted that “a small minority” do but she did not provided additional
details. In 1986, Wing noted that “…the (Aspergers) diagnosis has been helpful in increasing
understanding of the reasons for the crimes, and in deciding upon suitable methods of management
and care.”
With that historical context noted, research on Aspergers and violence is presented below based on
study type and organized by year, in ascending order. The most common type of study regarding
Aspergers and violence is the case study format.
CASE STUDIES:
Case studies provide detailed information about a patient. Sometimes, only one patient is the focus of
a case study, but more than one patient can be presented. However, each patient is presented
separately and not grouped together. While case studies can be informative, particularly in low
prevalence disorders, it is generally difficult to make generalizations based on them unless a very clear
recurring pattern occurs in many separate cases over time.
Mawson et. al (1985): Reported on a 44-year-old man with Aspergers. At age 16, he attempted to
strangle a girl. He was described as “laying in wait for girls from the school,” which appears to indicate
he had something negative planned towards them as he was also described as “girl mad.” At age 18,
he dropped a firework into a girl’s car and stabbed her in the wrist with a screwdriver but she did not
suffer serious harm. He stated he did this because he was jealous of her car and did not like women
drivers. He later jumped on the back of a girl in the park because of the way she was dressed. At age
22, he entered a neighbor’s house with a knife because he was upset at a dog sound and proceeded
to kick the animal and strike the female owner with a screwdriver. At age 25, he assaulted a crying
child by putting his hands over the child’s mouth but no serious harm occurred. He did the same to a
crying baby at a supermarket. He attacked another girl with a hacksaw because he felt she was
indecently dressed. He admitted that his behaviors were wrong but did not appear to be at all
distressed or remorseful. He had an interest in guns. While he clearly displayed evidence of reactive
violence, he also had thoughts of planned violence as evidenced by his pre-occupation with cutting up
babies and a desire to poison or shoot actresses. He did not carry out these behaviors but this was
prevented by him being kept in long term institutional care with maximal security. The authors
concluded that that the link between Asperger’s and violence was more common than had been
recognized at the time.
Baron-Cohen (1988): Reported on a 21-year-old man with Aspergers who was frequently violent (2 to
3 times a day) to his 71-year-old girlfriend, usually when he was worrying about his jaw. He stated he
enjoyed attacking her (slapping, thumping, pushing) because she was vulnerable and weak and that it
made him feel powerful. He was predicted to have a poor appreciation of his victim’s thoughts and
feelings which was confirmed via clinical interview as an important factor maintaining his violent
behavior. The patient’s father also reported that he always lacked an ability to know what other people
are feeling. In the psychiatric hospital, he struck a nurse when angry at least once every two weeks.
His girlfriend said the violence seemed uncontrollable and spontaneous. He had a long history of
violence to objects related to important people in his life. The author concluded that there was no
evidence that his violence was willful and that the question of why some people with Aspergers are
violent but others are not required further study.
Simblett and Wilson (1993): Presented three cases of people diagnosed with Aspergers who had
severe temper tantrums, 2 of whom had violent behavior. Of those who were violent, one was a 27-
year-old woman and one was a 23-year-old man. The man was noted to get violent when thwarted. The
violent behavior was not specified.
Chesterman and Rutter (1994): Reported on the case of RM, who, as a child was said to appear
indifferent to the distress of others, never offering comfort. He was diagnosed with Aspergers. He was
frequently disruptive and aggressive in school. He was bullied as a teenager. He made advances to
two female co-workers as an adult and was seeking revenge. He engaged in numerous sexual
offenses. At home, the most significant problem was loss of temper with considerable property damage
and physical assaults. The attacks were mainly directed towards his mother and were often
precipitated by his mother’s unwillingness to accept his need for an unvarying routine. This would also
make him more likely to commit a sexual offense. He once assaulted an interviewing police officer
because he was angry when it was suggested to him that he intended to commit an act of burglary. The
authors concluded that “The kind of behavioural problems typical of Asperger’s Syndrome are seen to
be clearly related to the offending behavior.”
Kohn et al. (1998): Reported on a 16-year-old boy with Aspergers who had a history of violent and
sexual assaults causing legal troubles. Multiple sources noted that he was unable to feel empathy. In
addition to sexual assaults, he violently attacked an old man and young boy. He hit his mother over
fear he would be turned into the police. He was noted to be odd-looking with a disturbing unchanging
facial expression. He tried to resolve any dispute with violence. It was correctly noted that his
aggressive acts are not a core feature of the disorder but that some patients with Apergers are indeed
violent. His aggressive behavior was related to his condition in that he had impairments in social
readiness and impaired theory of mind (appreciating the state of mind of others). It was urged not to
associate the link between Aspergers and violence as being more common until more research was
gathered for fear of stigmatizing such patients. It was noted that many clinicians believe that children
with Aspergers are more often the victim of violence than the aggressor.
Bankier et al. (1999): Reported on the case of a 25-year-old man with Aspergers who was admitted to
a psychiatric unit in Austria, partly due to outbursts of violence with attacks on his mother. No other
details were provided in the article on his violent behavior.
Murrie et al. (2002): Reported on six cases with criminal offenses, one of which involved physical
assault and another of which involved attempted murder. At least three of the six men had a history of
being bullied or exploited by others. Prior to committing their crimes, the patients had relatively law-
abiding non-violent backgrounds. The attempted murder case involved a 44-year-old man with
Aspergers who shot his psychologist who was taking part in a child custody evaluation for his two-
year-old son (he was married to a mentally ill woman). It was noted that he planned the murder for six
months, went to the psychologist’s house, and shot him in the head. The victim was severely injured
but survived. The shooter showed no remorse or guilt and believed that his actions would result in an
increased chance for him and his wife to retain custody of their child. On exam, he appeared somewhat
paranoid and narcissistic, with limited ability to take on the perspective of another.
The case of physical assault involved a 31-year-old man who followed two women to the female
bathroom at the zoo, threatened them with a knife, and bound them with pieces of rope cut into equal
lengths, which he brought from his car. He tied them intricately, paused, cut off the ropes, and then let
the women escape. Neither woman suffered physical harm. He had a blank facial expression and
showed no emotion. He noted that he had fantasies of binding women with rope. He admitted that
months before the offense at the zoo, that he loaded the rope and knife into his car. He spent years
following home attractive women who he found on the street and spent years procuring rope. Although
he appeared to have planned to tie the women up, he denied any plan to actually attack the women. He
was found guilty, given probation, and received outpatient treatment. One decade later, he had not re-
offended.
The authors reported a relationship between features of Aspergers and offending. They noted that
deficient empathy was a central feature among the Asperger’s patients who committed violent crimes.
They also raised the possibility that deficient empathy (or deficits in the ability to understand the
interpersonal impact of one’s behavior) could form the basis of an insanity defense. This was because
these deficiencies were “could theoretically distort a patient’s understanding of the nature and
consequences of his actions in much the same way that certain delusional beliefs could.” However, the
authors stated that patients with Aspergers who commit violent crimes are more likely to be held
criminally responsible if they do not also appear psychotic. In most of the cases, the authors noted an
association between the patients’ restricted, repetitive patterns of behaviors, interests, and activities
to the crimes they committed. It was also noted that a desire to form attachments to others while also
having social impairments can lead to violent behaviors in Aspergers. In some cases, it was noted that
the rigid sense of right and wrong in some patients with Aspergers can lead them to feel very frustrated
when they believe others have violated them, which can lead them to become aggressive.The authors
noted in their literature review that patients with Aspergers are particularly vulnerable to victimization
due to their interpersonal idiosyncracies and for being overly trusting. They noted that the vast majority
of people with Aspergers do not commit violent crimes.
Silva et. al. (2002): Speculated that serial killer and cannibal, Jeffrey Dahmer, had Aspergers and that
his homicidal behavior was intrinsically related to this diagnosis. He murdered 17 people between 1987
and 1991. The case is an example of planned violence. From an early age, Dahmer’s father noted that
he had poor eye contact, facial expressions lacking emotional glow, limited emotional expression, and
awkward body posture. He was a quiet boy, reclusive in elementary school, lacked social reciprocity,
and did not form appropriate developmentally appropriate peer relationships as a peer or adolescent.
His father and peers viewed him as socially inept. He did not appear interested in many social
activities and did not have any friends.
He was unable to form close romantic relationships as an adult. He was more comfortable with routines
body parts, internal animal structures, and bodily dissection. The authors provided a similar explanation
for how Aspergers can result in serial killing as was discussed in the case of the Unabomber (Silva et
al., 2003; see below). They noted that a depressive disorder, alcohol use, and environmental stressors
(e.g., parental divorce) could have also contributed to his homicidal behavior.
The authors did not personally evaluate Jeffrey Dahmer. They suggested that future research should
analyze large database of serial killers and explore the relationship between serial killing and pervasive
developmental disorder. Newman and Ghaziudinn (2008) stated that the diagnosis of Aspergers in
Jeffrey Dahmer by Silva et al. (2002) is doubtful but did not state why. Silva et al. (2004) later stated
that their work in no way suggests that all serial killers have autism spectrum disorders or that people
with autism are more likely to become serial killers.
Silva et al. (2003): This detailed case study stated that serial killer, Theodore Kaczyinski, (aka The
Unabomber), had Aspergers. The Unabomber became infamous for planting/mailing numerous home-
made bombs, which killed three people and injured three others. The case is an example of planned
violence. Silva et al. acknowledged that their diagnostic framework differed from that of many mental
health professionals who viewed the Unabomber as suffering from schizophrenia (many of whom
evaluated and diagnosed him with this condition). Schizophrenia is a type of psychotic disorder in
which one is detached from reality. The authors stated that a critical review of the evaluations that
were performed and the case history shows that the Unabomber did not meet DSM-IV criteria for
schizophrenia, that insufficient information was available to support the diagnosis, and that they did not
believe that the Unambomber’s profile was most consistent with a psychotic process (i.e.,
disengagement from reality). The authors cited others who also disagreed that the Unabomber was
psychotic. At best, the authors stated that the Unabomber may have at one point suffered from
psychosis due to delusional thinking, (strongly held false belief despite clear evidence that the belief is
false). However, they challenged whether his beliefs were actually delusional and did not believe there
was sufficient evidence that he was ever psychotic.
The authors noted the Unabomber’s marked and long-standing tendency towards social isolation
throughout his life. The Unabomber’s brother stated that he always presented with a disconnection from
others and was unable to understand people. He was said to have exhibited this trait since infancy. He
experienced great distress when exposed to loud noises. He made no close friends in elementary
school, was aloof, and was a loner, despite parental efforts to include him in social activities with his
peers. He played beside other children rather than with them. He was said to be unable to tolerate
human contact. He had generally hostile interactions with his parents throughout his life, which he
never showed remorse for. He was very socially isolated as an adolescent and blamed his parents for
this, even though there is no evidence that this blame was justified.
The Unabomber was gifted in math and admitted to Harvard at age 16. Math, bomb-making, wood, and
anti-technology were areas of intense, repetitive, hyperfocused, and solitary pursuit for him. He did not
socialize in graduate school or when he became an assistant professor of math at University of
California at Berkeley. He was regarded as a poor teacher, which the authors state was probably due
to poor empathy shown towards his students. He had failed relationships with women and
misinterpreted their intentions. He once made plans to mutilate the face of a woman who he said
degraded him by not being interested in a romantic relationship with him. He had little understanding of
socially inappropriate behavior and how to form and maintain interpersonal relationships.
The authors concluded that the Unabomber actually suffered from Aspergers. Although the authors
never personally evaluated him, they provided extensively detailed information to support the
diagnosis. The authors noted that even if the Unabomber had developed a psychotic disorder at one
point that he still would have qualified as having Aspergers. This is because schizophrenia typically
develops in early adulthood and is not present during infancy, whereas the Unabomber displayed signs
of Aspergers dating back to infancy. This would make sense since Aspergers is a disorder present
from birth and schizophrenia is not. They noted that some patients with Aspergers can be
misdiagnosed as psychotic but that he did appear to have paranoid ideas.
The authors stated that “autistic serial killers” may be less hesitant to formulate homicidal intentions
and carry them out because of deficits in taking the perspective of another which predisposed them to
experience their potential victims as being relatively devoid of life. They hypothesized that the social
isolation present in Aspergers can allow some serial killers to develop highly idiosyncratic fantasies
that can go unchecked by social norms. They stated that aspects of Aspergers can help dehumanize
others and play a role in serial killing behavior. They noted that there are other important factors
involved in causing serial killing in Aspergers such as aggression, psychopathic features, a dearth of
empathy, sexual drives (which are unfullfilled), and environmental factors/stressors. They noted that the
latter can be a decisive factor in the genesis of autistic serial killing behaviors. They also noted that
there was evidence that the Unabomber had antisocial personality disorder (psychopathy) which is a
pervasive pattern of disregarding and violating the rights of others since age 15. They also noted that
he had traits of a variety of other personality disorders. They cited the Scragg & Shah (1994) and
Siponmaa et al. (2001) studies as indicating an association between pervasive developmental
disorders and aggression as higher than previously thought.
Lastly, the authors noted that research has linked serial killing to schizoid personality disorder and that
schizoid personality and Aspergers are closely related. Schizoid personality disorder is a pervasive
pattern of detachment from social relationships and a restricted range of expression of emotions in
interpersonal settings, beginning by early adulthood (age eighteen or older) and present many contexts.
Barry-Walsh & Mullen (2004): Presented 5 cases of male patients with Aspergers who committed a
criminal offense. Of the five, two involved arson and will not be discussed here. Among the other three
cases, one was involved minor assaults related to episodes where he had become stuck and members
of the public tried to help him. In adolescence, he was placed in a secure hospital and was the victim of
considerable abuse. Another case involved a patient who assaulted his father after his father (who was
exasperated by his behaviors) confronted him about a fire he lit in the middle of the back lawn. During
the assault, he hit his father on the head and punched him several times. The third case involved minor
sexual offending and in one instance the patient put his hands around a girl’s throat when she declined a
blunt sexual advance. He assaulted his mother several years later. He had a preoccupation with
violence which decreased after receiving psychological counseling.
The authors stated that in each case, the offending behavior was understandable in the context of
Aspergers. However, this was not used as a legal defense in any case. It was noted that Aspergers
patients vary in terms of their capabilities and that some will have sufficient understanding to be held
morally responsible for their offending behavior. However, the authors concluded “…that patients with
Asperger’s Syndrome suffer from mental disorder and that their offending and subsequent disposition
must be placed in this context.”
Palermo et al. (2004): Presented one case of a patient with Aspergers and depressive disorder who
was admitted to the hospital for threatening to burn down his grandmother’s home after his extended
family forced him out of the house because of a property dispute. He also had depressive disorder. He
spent most of his time on the internet and had a particular interest in chemical weapons and fire bombs.
He had homicidal impulses towards his grandmother. The author stated there was inconclusive
evidence linking pervasive developmental disorders to violent behavior but that there was clearly a
need to clarify this relationship. The author believed that comorbid mental illness was the driving force
behind the offending behavior.
Schwartz-Watts (2005): Wrote a paper entitled “Asperger’s Disorder and Murder” in which three cases
of individuals with Aspergers in the U.S. who were charged with murder were presented. Case 1 was a
22-year-old man who had an interest in weapons. After drinking two beers, an 8-year-old boy
approached him on a bicycle to ask him about video games. He asked the boy to leave him alone and
the boy ran over his foot with the bicycle. He pulled out his gun and shot the boy. Both court-ordered
forensic psychiatrists and a retained forensic psychiatrist agreed that Asperger’s disorder was related
to the murder charge in that tactile defensiveness preceded the violent outburst. His fascination with
guns was said to be a manifestation of his stereotyped interests. He was sentenced to life in prison and
was housed with other mentally-disordered inmates.
Case 2 was a 35-year-old man who was charged with murdering a neighbor who entered his apartment
seeking money owed to him when he was on the phone. The victim struck the patient in the face and
touched his glasses, which the patient stated he was oversensitive to. He had a history of sensitivity
about his head or glasses being touched. The patient went to his room where he kept guns and the
victim followed. The patient shot the victim repeatedly with a .38-caliber revolver (he collected guns). He
then got another gun and shot the victim in the head to make sure the person was dead. He was
acquitted based on self-defense.
Case 3 was a 20-year-old man who murdered his girlfriend’s father. The victim had phoned him and
asked him to pick up some belongings at the house. The victim walked to his car to return one of the
belongings when the patient pulled a shotgun out of the trunk and shot him. Aspergers was linked to the
murder because the patient was said to have been unable to recognize the facial expression and
nonverbal cues of the victim when he approached the car. He stated it looked like the victim was going
to harm him and that he was defending himself. If true, all three cases were reactive murders rather
than planned murders. Case 3 was convicted of murder, sentenced to life in prison, and he was housed
in a unit for people with mental disorders.
Silva et al. (2005): Stated that serial killer, Joel Rifkin, who murdered between 9 and 17 people, had
Aspergers. He has been described as New York’s most prolific serial killer. This is an example of
planned violence. As a child, Rifkin did not fit in with the social fabric of the times. His social life was
thought to be very limited and he was considered a loner who was strange and unusual. He was unable
to develop long-term relationships except with the closest family members. He dressed awkwardly
(possibly because he was poor) and was the victim of bullying at school. He had poor non-verbal
communication including poor eye contact and difficulties with facial expression. He was unable to
interpret the facial expressions and body postures of others. He had awkward body posture and was
clumsy. He was frequently described as devoid of emotion and emotionally detached. He had deficits in
social and emotional reciprocity. He had a marked tendency to collect or store objects which resulted in
a disorganized and unclean living environment. He memorized long lists of Latin names for plants, stamp
and coin collecting, and fossil collecting. He also preserved and collected belongings from his victims.
He was terrified of change.
The authors noted that autistic serial killers appear to be predisposed to experience human beings more
as deconstructible living entities consistent with their tendency to view objects as composites of parts.
The lack of social feedback/controls due to Aspergers was said to facilitate the development of
inappropriate fantasies and be a factor that could be involved in homicidal behavior. It was stated that
he may have tried to exert control over the world by dehumanizing it. Stressors such as being bullied
and school failure could have played some role in his homicidal behavior.
It was noted that a psychologist who evaluated Rifkin for the defense opined that he suffered from
paranoid schizophrenia but the authors stated there was little evidence to support this according to
diagnostic criteria. It was noted that Rifkin’s problems were noted since early childhood which is much
more consistent with Aspergers than schizophrenia. The authors stated there was some evidence that
he suffered from attention-deficit/hyperactivity disorder. They also stated that he had a personality
disorder with schizoid, schizotypal, and antisocial traits. They acknowledged that the present state of
knowledge does not support a general association between criminal aggression and Aspergers. Of
note, it does not appear that the authors personally evaluated Joel Rifkin.
Haskins & Silva (2006): Pointed out that since patients with Aspergers are more likely to be male, and
males are more likely to be violent, that this can increase the risk for violent behavior in people with
Aspergers. They pointed out that having Aspergers does not automatically increase the risk of
criminality but that when criminality does occur, there can be features of Aspergers that can explain the
behavior (at least in part). These features were stated to be deficits in taking the perspective of
another and abnormal, repetitive, narrow interests. An excessive preoccupation on internal incentives
while ignoring social consequences (including legal sanctions) was said to be something that could lead
one to engage in criminal behavior. It was also noted that environmental factors such as bullying by
others, excessive noise level, family instability, and the presence of antisocial individuals may also
predispose persons with Aspergers to engage in antisocial behavior. Three cases were described in
this study, one of whom was diagnosed with Aspergers and depression but the case did not involve him
perpetrating violence.
Katz & Zemishlany (2006): Noted that violent behavior can occur on people with Aspergers when they
are disturbed or prevented from doing something related to their interests. Lack of empathy, problems
appreciating the consequences of their actions, high sensitivity, and a desire to be liked by others were
said to be factors that may cause people with Aspergers to commit physical and sexual assaults. They
noted that most people with Aspergers are law abiding and not involved in violent activity. However,
they noted that a minority among them are violent and that their criminal responsibility may be
challenged due to their condition.
The authors reported on three cases of individuals who were referred to their hospital for violent
assaults. In all three cases, the authors concluded that features of Aspergers were a major contributor
to their behaviors. The major explanatory feature was their inability to interpret social situations and
social messages, problems appreciating another person’s point of view, and not appreciating the
consequences of one’s actions. It was noted that people with Aspergers are quick to confess because
they do not feel guilt, believe their responses were appropriate to the situation, and are not aware of
the implications of the confession.
Case 1 was a 30-year-old male who had frequent furious verbal and physical outbursts directed to his
family and others. He pushed his mother, causing her to fracture her pelvis. He broke dishes, furniture,
and punched the walls. His violence was usually due to feeling misunderstood, not having his wishes
fulfilled, or feeling offended. After being rebuffed by a 27-year-old woman who he fell in love with, he told
someone that he intended to kill her because she offended him. His outbursts became more frequent
and violent. On examination, he was noted to have a complete lack of understanding of the social code.
It was stated that his outbursts were mostly caused by his inability to interpret social situations
correctly. In addition to Aspergers, he was diagnosed with attention definition disorder. It was
suggested to the court that he not be prosecuted for his offenses, since they stemmed from his illness
and were committed without criminal intent. This recommendation was accepted by the court and he
was sent back to the psychiatric hospital.
Case 2 was a 22-year-old man who had a history of attacking family members, especially his sister,
both verbally and physically. This led to a restraining order which banned him from his parents’ home.
He disregarded the order and assaulted his sister and father. He was arrested and admitted to a
psychiatric hospital. He also had a total lack of understanding of social codes, showed no interest in
social interaction, and had a near complete lack of empathy. He did not attempt to explain the assaults
on his family and was not capable of comprehending the physical and emotional damage he caused
them. The same recommendations were made to court as in case 1, which were accepted, court
procedures were halted, and he was sent back to the psychiatric hospital.
Case 3 was a 38-year-old man who stated he got married because it was the proper thing to do. He
hoarded newspapers and assaulted his wife if she threw them away. He ignored his wife when she
came to visit him in the hospital. Based on the authors’ recommendations that Aspergers contributed to
his behaviors, he was treated in a psychiatric hospital rather than tried in court. After treatment, a one
year follow-up for each case showed that they lived within the community with their families and did not
show signs of aggression.
FOLLOW-UP STUDIES:
These types of studies follow patients over time and evaluate whether certain events take place or not,
such as violent behavior and other criminal behavior. One such study falls in this category and is limited
by a very small sample size.
Larsen & Mouridsen (1997): Followed up 9 children with Asperger’s in Denmark for over 30 years and
found that only one had committed a crime (theft) at age 24 and received a fine.
FACILITY STUDIES:
These types of studies evaluate groups of patients in prisons or mental health facilities to study the
prevalence of Aspergers and violence:
Scragg & Shah (1994): All 392 males at a secure prison hospital in England were studied and 1.5 to
2.3% were found to have Aspergers, which was reported as greater than the prevalence in the general
population (0.36%). This implied that a greater percentage of Asperger’s patients were in jail than in the
general population. Of the 6 men found to be violent, three were physically violent, one committed
arson, and three showed aggressive behavior on the wards (e.g. threats). The authors concluded that
“…in fact there may be an association between AS and violent behavior and that AS may be overlooked
as a diagnosis at secure hospitals.” (AS was their abbreviation for Asperger’s syndrome). The authors
acknowledged that violence may be rare in Aspergers but that when it does occur it may be linked to
deficits found in the disorder. For all six cases of violence, lack of empathy was reported. The
conclusion of this study was criticized by Hall and Bernal (1995) for using an improper comparison
group from another county, educational background, age, and social background. They also questioned
whether the difference in prevalence reported was due to a real difference or due to chance. Hall and
Bernal (1995) stated that “It is important that readers do not conclude that AS is associated with a(n)
increased tendency to commit violent acts when this has not been proven.”
Raja and Azzoni (2001): Italian study of Aspergers compared to those diagnosed with other
psychiatric disorders admitted to an emergency psychiatric clinic. Of 2500 hospital admissions, only 5
had Aspergers (0.2%). Of these five patients, all had a history of aggressive or violent behavior. All five
patients were violent to their relatives. The authors stated that in their hospital, violent behavior in
Aspergers seemed to be common. However, Langstrom et. al (1999) pointed out that this was not a
representative sample of people with Aspergers because violence towards others was a strong
contributing reason for referral.
Siponmaa et al. (2001): Examined 126 young offenders (ages 15-22) in Sweden who had committed
serious crimes, the majority of which were violent. Of these offenders, 3% had definite Aspergers and
none were autistic. Another 12% had a definite pervasive developmental disorder (PDD) that could not
be classified as either Aspergers or autism. Thus, 15% had some type of definite pervasive
developmental disorder. In addition to this, another 12% had a probable PDD. In terms of raw numbers,
34 of the 126 offenders (27%) had definite or probable form of PDD (19 were definite). Five of the
patients with a PDD diagnosis had evidence of psychosis. Three of the four patients with definite
Aspergers were sentenced to compulsory institutional psychiatric care. The authors viewed the rate of
PDD as “particularly striking” and were confident that it represented at least a 15-fold increase in the
general population. However, since the study was retrospective and relatively small, they noted that a
larger study was needed with control groups before more firm conclusions can be made.
Murphy et al. (2003): Examined differences between adult patients (ages 20-40) with Aspergers,
schizophrenia, and personality disorders in a high security psychiatric hospital in England. There were
13 people in each group. The authors found that the Asperger’s group had lower rate of violent offenses
leading to hospital admissions and lower total violence. The offenses in the Asperger’s group tended to
commit less severe crimes. Offenses in the Asperger’s group tended to be associated with particular
problems such as externalized misplaced blame, difficulty with perspective-taking, and difficulty in
appreciating the consequences of their actions.
Anckarsater (2005): Swedish study of 89 perpetrators of severe crimes against other persons finding
that 3 had Aspergers (3%) and that 15 had a form of autism (17%), meaning that 20% had a history of a
pervasive developmental disorder. This is consistent with the rate found in the Siponmaa study.
Woodbury-Smith et al. (2006): Studied self-reported offending in a general population-based sample
of 25 English adults with Aspergers/high functioning autism and compared to a non-Aspergers
comparison group composed of 20 people. The overall rate of lawbreaking was significantly lower in
Aspergers patients than the comparison group. However, the self-reported history of violent behavior
was similar between the Aspergers group (30%) and the comparison group (25%). The findings
challenged an association between Asperger’s disorder and violence.
However, only 45% of the 102 eligible subjects decided to participate, which could mean that the study
had a selection bias if those who declined to participate had a higher incidence of violent behavior than
those who agreed to participate. The study was limited by a small sample size.
Allen et al. (2008): Examined the prevalence of Aspergers and offending behaviors among adults in
South Wales, England. The results were not generally supportive of a link between Aspergers and
offending behavior but the authors noted that numerous methodological problems with their study may
have impacted the obtained results.
Mouridsen et al. (2008): Examined 313 former Danish psychiatric inpatients with pervasive
developmental disorders (114 of which had Aspergers) and found a similar rate of convictions for
persons with Aspergers disorder compared to a control group made of 342 people (18.4% vs 19.6%,
respectively). Of the controls, 2.3% committed violent crimes compared to 1.8% of Aspergers patients.
Neither rate was statistically different from one another. Of the Asperger’s group, 3.5% committed
sexual offenses compared to 0.9% of the control group, a finding that approached statistical
significance. The authors concluded that “…serious crime is a rare occurrence in PDD.” Of note, this
was a matched control study, in which controls were matched with Asperger’s patients on certain
demographic variables.
Langstrom et. al (2009): Swedish study that examined 422 patients with autism or Asperger’s between
1988 and 2000 who all committed some type of criminal offense. The study found that 31 individuals
(7%) committed violent non-sexual crimes. Violent individuals were more likely to have Aspergers than
autism and tended to have a comorbid psychotic and substance abuse disorder. It was concluded that
violence in Asperger’s disorder is related to similar co-morbid mental health problems similar to what is
found in violent individuals who do not have Aspergers. It was also noted that due to the disabling
nature of Aspergers and its low prevalence that it is not likely to account for a large proportion of violent
crimes in society. The study could not answer if Aspergers was associated with an increased risk of
violence compared to the general population.
LITERATURE REVIEWS:
These types of studies evaluate multiple research studies on a certain topic to determine if a certain
pattern is present.
Ghaziudinn et al. (1991): This review of 21 prior studies critiqued the speculated link between
Aspergers and violence. The authors found that only a small minority (2.27%) of those with Aspergers
would commit a violent act serious enough to cause legal trouble. They concluded that violence is not
common in Aspergers and that further speculation of a link between Aspergers and violence only serves
to increase the stigma and distress of the patients and their families. However, this critique was itself
criticized by Kohn et al (1998) for being overly exclusive in the studies selected for review (e.g.,
excluding some studies with comorbid psychiatric diagnoses) and for a very restrictive definition of
violence (e.g., not including patients with aggressive outbursts or physical aggression because enough
details were not provided). The definition of violence in the study was any act for which the person can
be charged for criminal behavior (such as murder, arson, etc.) or which resulted in a substantial
physical injury to another person, with or without the intent to do so. If the excluded studies were
included, Kohn et al. (1998) stated that the prevalence of aggression in Aspergers would be 20% as
opposed to 2.27%. The conclusions of Ghaziudinn et al. were also criticized as possibly inaccurate due
to a failure to detect Aspergers in prisons and other secure settings.
Tantam (2003): Reported that out of 262 patients that the author had seen that 40% of parents
reported hitting people to be a problem. The author stated that aggression in Aspergers can occur for
different reasons: 1) retaliation, 2) outrage, 3) a membership in a deviant group such as other
marginalized or disruptive children (easily egged on by such people), 4) special interests (e.g., powerful
others, fire), 5) defensiveness (e.g., stopping an aversive stimulus such as loud noises), and 6) gaining
ascendancy.
It was noted that while patients with Aspergers are bullied and victims of aggression, that they may take
out their own feelings of aggression about victimization incidents against someone other than the
perpetrator at a later time who is more vulnerable. The target of aggression was reported to most likely
to be the mother or (if applicable later in life), a spouse. Retaliatory aggression was described as
sudden and unexpected. Aggression in Aspergers was noted to rarely result in criminal prosecution. The
author stated that he only knew of one man with Aspergers convicted of attempted murder (for
threatening to kill his mother with knife). He stated he did not personally know of a patient with
Aspergers who was interested in violence who later became a perpetrator of violence.
Tantam noted that the most serious aggression in Aspergers occurred when the patient felt that he/she
was so alone and powerless that he/she feels that there is nothing to lose. In these situations, the
author stated that an act of violence can become the stuff of daydreams and later acted upon. This
would appear to fit into planned violence. The author stated this kind of aggression has a detached
quality, like a science experiment (e.g., wanting to see what would happen).
Newman & Ghaziudinn (2008): One of the same authors as above contributed to this updated case
review of Aspergers and violence. The authors reviewed 17 articles (most of which were case reports)
that suggested an association between Aspergers and violent crime (defined as causing significant
harm to another person). There were 37 cases described in these studies. Of these, 11 cases (29.7%)
had a definite psychiatric disorder and 20 cases (54%) had a probable psychiatric disorder at the time
of committing the crime. In 6 cases, (16.2%), there was no evidence of a comorbid psychiatric disorder.
The authors emphasized the role of psychiatric disorders in the occurrence of violent crime in people
with Aspergers. They noted that there has been speculation in the media of an association between
violence and random acts of campus violence in the United States. The authors concluded that “…when
violent crime occurs in the setting of Asperger syndrome, the cause may lie as much in the diagnosis of
AS (Apserger syndrome) as in the other factors that contribute to its occurrence in the general
population, including comorbid mental disorders.” The authors noted that their study did not attempt to
answer if people with Aspergers are at greater risk of committing violent crime than in the general
population.
Freckelton (2011): Legal review which concluded that physical violence in Aspergers is more likely to
occur in response to what is perceived as a sudden, distressing invasion of personal space or a
panicked reaction. The reaction can be instant and intense, reflecting a primitive reaction to threat. In
other words, it tends to be an impulsive reaction to perceived danger or perceived grievance. He noted
that decreased empathy, poor sensitivity, low responsivity, and obsessiveness have the potential to lay
the foundation for the commission of a crime. While patients with Aspergers can behave erratically and
impulsively, he noted that they are capable of thoughtful deliberation before acting.
LEGAL OPINIONS:
Legal Opinions are decisions made by a justice or justices of a court regarding a particular topic.
See Katz & Zemishlany (2006) in the case studies section for a discussion of three legal decisions
that set legal precedent for Asperger’s patients not being held criminally responsible for violent
behaviors due to their condition. The patients were instead treated in a psychiatric hospital. It was
noted that each case must be considered individually to decide whether an Asperger’s patient should be
held criminally responsible.
The R v Kagan Decision (2007): The case of a man with Asperger’s disorder (Mr. Kagan) who
attacked a man with bear spray and stabbed him multiple times in the back with a pocket knife which
caused a punctured lung and potentially life threatening injuries. Mr. Kagan claimed he acted in self-
defense. The judge (Justice McDougall) decided that Asperger’s disorder was not an automatic excuse
for Mr. Kagan’s actions that would absolve him of responsibility for his actions. However, it can lessen
the sentence that would have otherwise have been imposed because the judge decided that Aspergers
does affect the way that the offended interprets the words and actions of those he might encounter. In
this case, a non-custodial sentence to be served in the community was imposed.
CONCLUSIONS:
1. There is no epidemiological scientific research linking Asperger’s to planned acts of committed
violence. The vast majority of case studies also do not document such as association. However, one
group of researchers has published several peer-reviewed scientific reviews of individual cases stating
that The Unabomber, Jeffrey Dahmner, and Joel Rifkin had Aspergers, which all involved planned
violence leading to multiple murders. In addition, I have previously hypothesized (long before the
Newtown shootings) in a prior blog entry that the Colorado movie theatre shooter may have had
Aspergers.
2. People with Aspergers are more likely to be the victims of aggression than the aggressor.
To begin with, Asperger’s disorder (sometimes called Asperger’s
syndrome) is considered a neurodevelopmental disorder, meaning
that it is the result of a neurological disorder present from birth. It
is also referred to as a type of pervasive developmental disorder
(PDD). It is characterized by a qualitative impairment in social
interaction and restricted, repetitive, and stereotyped patterns of
behavior, interests, and activities. Examples of the former include
marked impairment in non-verbal behaviors (e.g., eye contact,
gestures) used to regulate social interaction, failure to develop
developmentally appropriate peer relationships, lack of social and
emotional reciprocity, and lack of spontaneous seeking to share
enjoyment, interests, or achievements with other people.
3. Most people with Aspergers are not violent.
4. A subset of people with Aspergers are violent, which can lead to criminal behavior, including
murder.
5. Most patients with Aspergers who commit violent acts have a co-morbid mental health disorder but
not all do.
6. Features of Aspergers can be related to why violent behavior occurs in some patients.
7. There is legal precedent for Aspergers being used to absolve one of criminal responsibility for
violence or to mitigate the sentence.
8. More research, with many more subjects, needs to be done to determine if people with Aspergers
have a greater risk of violence than the general population.
9. Many studies on Aspergers and violence (including all facility studies) have been conducted outside
of the U.S. Much more research on this topic is needed in the United States, particularly facility
studies.
10. There is rarely a single reason for violent behavior. Rather, causes of violent behavior, including
planned violence, are complex and the result of many different variables interacting together.
Formal reference for this article: Carone, D.A. (2013). Asperger’s Disorder and Violence: A
Review. Retrieved from http://www.medfriendly.com/aspergers_violence_autism
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