Psychiatric Comorbidities in Asperger Syndrome – Too Often Unrecognized?

Psychiatric comorbidities in Asperger syndrome (AS) and High Functioning Autism (HFA) are extremely common, both in children¹ and in adults,^2,3 and are likely underrecognized because of the difficulties and challenges involved in reaching an accurate diagnosis.⁴

Speaking to this concern, Luigi Mazzone, MD of the Child Neuropsychiatry Unit, Department of Neuroscience, I.R.C.C.S. Children’s Hospital, Bambino Gesù, Rome, Italy and colleagues explore the overlap between AS/HFA and psychiatric conditions, and the resulting diagnostic challenges by reporting findings of a literature search of clinical studies assessing psychiatric comorbidities in individuals with AS and/or HFA, from January 2000 to December 2011.⁵

Internalizing Disorders

The literature search found a strong association between AS/HFA and depression, bipolar disorders, and anxiety. The authors describe a “bidirectional association” between internalizing disorders and autistic symptoms, with a higher prevalence of anxiety disorders in AS patients and a higher rate of autistic traits in patients with mood and anxiety disorders. People with AS also displayed more social anxiety symptoms compared to healthy controls.

A strong association was found between AS and obsessive compulsive disorder (OCD). However, the authors add that it is difficult to discriminate between the repetitive behaviors of OCD and those inherent in AS. One study, for example, found a similar pattern of obsessions and compulsions in the HFA/AS and the OCD groups, with 25% of HFA/AS individuals receiving a formal diagnosis of OCD.⁶ Mazzone and colleagues note that similar serotonergic abnormalities may be present in both populations, and that medications effective in OCD have also been found effective in controlling ritualistic behaviors in ASDs.⁷

Externalizing Disorders

The authors cite numerous studies pointing to an association between AS/HFA and attention-deficit hyperactivity disorder (ADHD), disruptive behavior, and conduct disorders. They note that according to DSM-IV–TR criteria, ADHD cannot be diagnosed in the context of an ASD.⁸ However, they suggest that there is a “real, frequent, and relevant” comorbidity, and possibly a “phenotypic overlap” between these conditions, suggesting that perhaps these conditions may be part of a common spectrum.

The authors touch upon the question of violence in HFA/autistic disorder—a highly relevant concern in light of the recent school shooting in Newtown, Conn., where a 20-year-old male with a purported diagnosis of Asperger disorder killed 20 children and six adults, before turning the gun on himself.⁹ Mazzone et al note that the relationship between AS/HFA and psychopathy is “controversial,” but is suggested by some studies showing an increased risk for crimes in AS that “may be attributable to either a lack of insight typical of AS and/or to co-occurring psychiatric disorders.”^10-12 They cite a study suggesting that individuals with HFA are overrepresented in the criminal population, as compared to the general population.¹³ And they note that “most of the individuals suffering from AS who commit violent crimes also show additional psychiatric disorders.”¹¹

However, they also cite evidence to the contrary, including data from the original studies by Hans Asperger, showing that individuals with AS/HFA are not more likely to become offenders or behave antisocially than any other group in the general population. Other studies, too, have failed to detect higher rates of criminal behavior.¹⁴ In fact, the authors state, individuals with AS may respect law more than others because they “often show a strong sense of right and wrong, and once they have understood the rules, they are more likely stick to them—even more rigidly than other people.”¹⁵

Tic and Other Disorders

The review found a high comorbidity between Tourette Syndrome and other tic disorders. The authors also note that although historically autism was considered a form of early psychosis, there are few studies investigating this association and that this is often a mistaken diagnosis.