5 Key Issues About Comorbidity in Geriatric Bipolar Disorder

Physical illnesses are common in the elderly, with an average of 3 or 4 medical conditions. This population is particularly vulnerable to metabolic syndrome (up to 50%), hypertension (45% to 69%), diabetes mellitus (18% to 31%), and cardiovascular disease (9% to 49%) [see Reference 8 here] Cardiovascular comorbidity partially explains the increased rates of cerebrovascular disease in late-life BD, and vascular events may be etiologically involved in late-onset BD. Cardiovascular and other medical conditions probably arise from a combination of factors, including biological stressors inherent to BD (eg, inflammation, oxidative stress), lifestyle (eg, dietary habits, physical activity, substance use), and psychotropic medication exposure (eg, antipsychotics, mood stabilizers).

Cognitive dysfunction affects many older BD patients, and it is often associated with functional disability. Although impairment exists in multiple domains, including attention, executive function, processing speed, working memory, and verbal memory, it is unclear whether dysfunction is comparatively more severe in older BD patients. As with medical comorbidity, cognitive dysfunction has a number of causes in BD, including inflammatory and oxidative processes. Medications with higher anticholinergic burden may be a contributing factor (eg, certain antipsychotics), as may be substance use and cardiovascular disease.

Clinical presentation of geriatric BD must be interpreted cautiously, since most study samples are cross-sectional and are probably survivor cohorts. Existing therapies (eg, cholinesterase inhibitors) have not been effective in treating cognitive dysfunction, although lithium may be a therapeutic candidate. Clinicians could start by using treatments with both large-scale randomized controlled trial (RCT) evidence in adults and some data in older adults, followed by medication with evidence of fewer risks. Conclusions and treatment recommendations based on the extant literature must be tempered with consideration.

Psychiatric comorbidities are less common in geriatric patients with BD than in younger adults with BD. Since there are higher rates of familial transmission in early-onset cases and late-onset cases are usually more associated with neurological comorbidity, it is possible that early-onset BD and the late onset variant are different illnesses. Clinical presentation and course of illness in later life also vary. Older patients may have more severe depressive episodes and less severe manic episodes than younger patients.