Anxiety disorders in 318 bipolar patients: prevalence and impact on illness severity and response to mood stabilizer

The aim of this study was to assess the frequency and impact of anxiety disorders on illness severity and response to mood stabilizers in bipolar disorders.

318 bipolar patients consecutively admitted to the psychiatric wards of 2 centers as inpatients were recruited. Patients were interviewed with a French version of the Diagnostic Interview for Genetic Studies providing DSM-IV Axis I diagnoses and demographic and historical illness characteristics. Logistic and linear regressions to adjust for age and sex were performed.

In a population with mostly bipolar type I patients (75%), 24% had at least 1 lifetime anxiety disorder (47% of these patients had more than 1 such disorder), 16% of patients had panic disorder (with and without agoraphobia, and panic attacks), 11% had phobia (agoraphobia without panic disorder, social phobia, and other specific phobias), and 3% had obsessive-compulsive disorder. Comorbidity with anxiety disorders was not correlated with severity of bipolar illness as assessed by the number of hospitalizations, psychotic characteristics, misuse of alcohol and drugs, and suicide attempts (violent and nonviolent). Bipolar patients with an early onset of illness had more comorbidity with panic disorder (p <.05). Anxiety disorders were detected more frequently in bipolar II patients than in other patients, but this difference was not significant (p =.09). Bipolar patients with anxiety responded less well to anticonvulsant drugs than did bipolar subjects without anxiety disorder (p <.05), whereas the efficacy of lithium was similar in the 2 groups. There was also a strong correlation between comorbid anxiety disorders and depressive temperament in bipolar patients (p =.004).

Patients with bipolar disorders often have comorbid anxiety disorders, particularly patients with depressive temperament, and the level of comorbidity seems to decrease the response to anticonvulsant drugs.