Patterns of Axis I comorbidity in relation to age in patients with Bipolar Disorder : a cross-sectional analysis

Background: Several data indicate that the clinical course and treatment response of Bipolar Disorder (BD) is influenced by comorbidity. However, whether differences in comorbidity patterns exist in relation to classes of age remains debated. The present study was aimed to evaluate differences in terms of cross-sectional Axis I comorbidity among young (<= 30 years), adult (> 30 and <= 45 years) and older adult patients with BD (> 45 years). Methods: Study sample included 508 patients with BD, subdivided into 3 groups of age: <= 30 years (n = 52), > 30 and <= 45 years (n = 186) and > 45 years (n = 270). Demographic and clinical variables, with specific emphasis on Axis I comorbidity, were compared across the different groups using chi-square tests. Furthermore, a binary logistic regression was performed. Results: Two-hundred eleven patients (41.5%) showed at least another concomitant Axis I disorder. The 3 groups were homogenous in terms of type of diagnosis (type 1 or 2 BD) and gender. However, they were different in terms of cross-sectional Axis I comorbidity (p = 0.001) with a higher frequency of substance abuse (p = 0.04) and Anorexia (p = 0.014) in young patients, and of Obsessive Compulsive Disorder in adult patients (p =- 0.001). In addition, young patients showed more frequently the presence of a second comorbid Axis I condition compared to the other sub-groups (p = 0.05). With regard to the type of abuse, young subjects were more frequently cannabis (p < 0.001) and cocaine abusers (p < 0.001) compared to the other subgroups. Limitations: Lifetime Axis I and Axis II and cross-sectional Axis II comorbidity patterns were not analyzed. Conclusions: Preliminary results from the present exploratory study seem to suggest different profiles of cross-sectional Axis I comorbidity and abuse in bipolar patients in relation to age. This aspect should be taken into account for the choice of pharmacological treatments and global management in clinical practice.