• age of onset
• bipolar disorder
• elderly
• follow-up
• late life
• older age bipolar disorder

ABSTRACT
Background: Although elderly represents more than 25% of all the bipolar disorder (BD) patients, literature about BD in old age is still limited. Method: A retrospective chart review was conducted to investigate the course of BD in late life. One hundred patients ≥ 65 years were selected according the following criteria: 1) the diagnosis of a depressive episode according to the International Classification of Disease, Tenth Edition (ICD-10), 2) a Clinical Global Impression – Severity of illness ≥ 4 (i.e. “moderately ill” or above) and 3) a follow-up duration ≥ 18 months. The subgroups of patients with a definite diagnosis of BD at the end of the observational period (N = 60) were subdivided according to age at onset terciles in very late age at onset (VLOBD), late (LOBD) and regular age at onset of BD (ROBD), then we compared follow-up morbidity differences between the different groups. In addition, we investigated the implications of somatic comorbidities on the course of the BD. Results: From the index episode to the end of follow-up, 17 patients reported a diagnostic changes from unipolar depression to BD spectrum. Interestingly, both groups of patients with VLOBD and ROBD spent significantly more time with symptoms and depressive symptoms compared with the LOBD group. The VLOBD patients had a higher percentage of time spent in major episodes in comparison to the LOBD group and a higher percentage of time spent both with (hypo)manic symptoms and (hypo)manic episodes in comparison to the other two groups. Both time with symptoms and time with depressive symptoms were significantly positively associated with obesity. Conversely, diabetes mellitus type 2 was found to be significantly positively associated with time with (hypo)manic symptoms.
Conclusion: VLOBD and somatic metabolic comorbidities specifically and differentially increase BD morbidity in the very old age.