Recent Biological and Genetic Findings

Schizophrenia, bipolar disorder, and autism spectrum disorders (ASD) are some of the most well-known psychiatric disorders, and all are chronic and disabling. At face value, the diagnostic criteria, characteristics, and age of onset have little in common. However, more and more studies support that the three disorders share some genetic traits.

Here is a quick summary of the three disorders:

Schizophrenia:

• The National Institute of Mental Health (NIMH) estimates that 1.1% of the United States population has schizophrenia.
• According to the American Psychiatric Association's Diagnostic and Statistical Manual (DSM-IV), often referred to as the bible of psychiatry, the usual age of onset is the mid-20s.
• The disorder is characterized by disorganized speech and thought, hallucinations and delusions (DSM-IV).

Bipolar Disorder:

• A mood disorder that is characterized by extreme mood fluctuation between depression and mania/ hypo-mania (elated mood).
• Average age of onset is 21.
• The NIMH estimates that 2.6% of the U.S. population has either bipolar I or bipolar II disorder.

Autism Spectrum Disorders (ASD)

• The Centers for Disease Control (CDC) estimates that 1 in 88 children in the United States are autistic.
• ASD is generally diagnosed during childhood.
• According to the DSM-IV ASDs are characterized by “restrictive, repetitive, and stereotyped patterns of behavior, interests, and activities.”

A recent study published in the Archives of General Psychiatry by Sullivan and colleagues (2012) reviewed three data sets of children with autism and family history of mental illness. Two of the studies were in Sweden- one nationally and one restricted to the county of Stockholm, and the other was in Israel. The intent of the research was to determine whether schizophrenia or bipolar disorder was a risk factor for autism.

In all three studies, the authors found that having a parent or sibling with schizophrenia increased the likelihood of a child having an autism spectrum disorder. The same was true for children who had a parent who was bipolar, but to a lesser extent.

The authors conclude that there is a genetic phenotype between the three disorders. What is particularly interesting is that at one type schizophrenia and autism were believe to be two sides of one coin, in that each disorder fell on the extreme end of a spectrum. Whereas autism had an extreme restricted and rigid organization of thought, schizophrenia was anything but. This theory has largely fallen by the wayside, but there the two disorders do seem to have some link.

References:

American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed., text rev.). Washington, DC
Centers for Disease Control and Prevention. (2012, March 30). Prevalence of Autism Spectrum Disorders- Autism and Developmental Disabilities Monitoring Newwork, 14 Sites, United States, 2008. MMWR, 61(3), pp. 1-22.
National Institute of Mental Health. (2012, 2012). Statistics. Retrieved from http://www.nimh.nih.gov/statistics/index.shtml
Sullivan, P. F., Magnusson, C., Reichenberg, A., Buman, M., Dalman, C., Davidson, M., et al. (2012). Family History of Schizophrenia and Bipolar Disorders as Risk Factors for Autism. Archives of General Psychiatriy, Published July, 2012.

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