Q: Which is the most common neuropsychiatric disorder in bipolar disorder?
A: Bipolar disorder is associated with both medical and psychiatric comorbidity. Disparate medical conditions include, but are not limited to, obesity, diabetes, metabolic syndrome, and thyroid disorders. In addition, individuals with bipolar disorder are differentially affected by several neurological disorders. The neurological disorders commonly encountered are migraine, tremors, movement disorders, and in some cases, dementing disorders. During the past decade, several clinical and epidemiological studies have reported on medical comorbidity in general and more specifically neurological comorbidity.
Results from these studies indicate that migraine headache is prevalent and may differentially affect individuals with bipolar disorder relatives to people with major depressive disorder. Moreover, it appears as though migraine headaches in a bipolar individual are associated with a more severe illness course as indicated by earlier age of onset; more anxiety comorbidity; higher use of polytherapy, disability, and welfare benefits; decreased quality of life; and increased utilization of services. It is currently estimated that the lifetime migraine prevalence rate of bipolar disorder ranges from 15% to 77%. The highest reported prevalence rate of reported migraine is in individuals with bipolar spectrum disorders (eg, bipolar II disorder). An interesting observation is that individuals with unipolar disorder and migraine headaches appear to cluster more “bipolar traits” (eg, irritability, seasonal variation, and family history of migraines). Available neurobiological and treatment data indicate that bipolar disorder and migraine are discreet conditions with overlapping substrates. It has been hypothesized that bipolar disorder and comorbid migraine comprise a distinct subphenotype of bipolar disorder. Practitioners are encouraged to screen their patients for the presence/history of migraine headaches.