Psychiatric comorbidity in older adults with bipolar disorder.

Introduction: Comorbidity patterns and correlates among older adults with bipolar disorder (BPD) are not well understood. The aim of this analysis was to examine the prevalence of comorbid PTSD and other anxiety disorders, substance abuse and dementia in a population of 16,330 geriatric patients with BPD in a Veterans Health Administration administrative database.

Methods: Patients were identified from case registry files during Federal Fiscal Year 2001(FY01). Comorbidity groups were compared on selected clinical characteristics, inpatient and outpatient health resource use, and costs of care.

Results: Four thousand six hundred and sixty-eight geriatric veterans with BPD were comorbid for either substance abuse, PTSD and other anxiety disorder, or dementia (28.6% of all veterans with BPD age 60 or older). Mean age of all veterans in the four comorbidity groups was 70.0 years (+/-SD 7.2 years). Substance abuse was seen in 1,460 (8.9%) of elderly veterans with BPD, while PTSD was seen in 875 (5.4%), other anxiety disorders in 1592 (9.7%), and dementia in 741 (4.5%) of elderly veterans. Individuals with substance abuse in this elderly bipolar population are more likely to be younger, minority, unmarried and homeless compared to elderly bipolar populations with anxiety disorders or dementia. Inpatient use was greatest among geriatric veterans with BPD and dementia compared to veterans with BPD and other comorbid conditions.

Conclusion: Clinical characteristics, health resource use and healthcare costs differ among geriatric patients with BPD and comorbid anxiety, substance abuse or dementia. Additional research is needed to better understand presentation of illness and modifiable factors that may influence outcomes.