Clinical research: Autism, bipolar disorder may often overlap

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As much as 30 percent of children diagnosed with bipolar disorder may also have autism, suggests a study published in the June issue of the Journal of Clinical Psychiatry¹.

Bipolar disorder affects about 1 percent of children and is characterized by severe mood swings between mania and depression. Some of the symptoms, such as irritability and aggression, are also common in autism.

Clearly distinguishing bipolar disorder from autism is important, as treatment for one disorder may not be beneficial for the other. Symptoms of one disorder may also mask diagnosis of the other.

For example, one 8-year-old boy in the study was hospitalized six times after age 5 for aggressive outbursts that involved harm to himself and others. After 10 years old, when these outbursts calmed as a result of successful therapeutic treatment, his caretakers also noted that he had rigid thinking, had deficits in social skills and isolated himself from his peers. At 11, he was diagnosed with pervasive developmental disorder-not otherwise specified.

To address possible comorbidity between bipolar disorder and autism, the researchers looked at 155 children with bipolar disorder, from 6 to 17 years of age, and 487 of their first-degree relatives. Trained psychologists diagnosed autism in 47, or about 30 percent, of these children.

The children with both diagnoses have symptoms of bipolar disorder that are similar to those of children who have bipolar disorder alone, the study found. The children who have both disorders were diagnosed with bipolar disorder at a younger age, however. These children also have elevated symptoms of grandiosity — inflated self-esteem or belief that they have special powers.

The researchers also looked at family history of bipolar disorder in this group, and in another group of 162 children with attention deficit hyperactivity disorder (ADHD) and 511 of their first-degree relatives. They also looked at 136 children with no symptoms of ADHD, autism or bipolar disorder, and 411 of their first-degree relatives.

Family members of children with bipolar disorder are significantly more likely to have a family history of psychosis than those of children with ADHD or controls. Family members of children who have both autism and bipolar disorder have the same risk of psychosis as do family members of children with just bipolar disorder.

This suggests that the children diagnosed with both disorders have true bipolar disorder and not just symptoms of autism misdiagnosed as bipolar disorder, the researchers say.