Cognitive Impairment and Lithium in Older Age Bipolar Disorder—A Narrative Review

Older age bipolar disorder (OABD), defined as bipolar disorder (BD) in adults aged 50 years and older, is associated with significant cognitive impairment and elevated dementia risk. Cognitive impairment is common but heterogeneous, with reproducible subgroups (preserved, mild, severe) and the largest deficits in verbal learning and memory. Longitudinal data argue against uniform progressive decline, though a subset shows worse trajectories linked to brain health and episode burden. BD more than doubles dementia risk, possibly by reducing cognitive reserve and worsening brain health through neuroinflammation and vascular disease. A recent study identifies amyloid sequestration of endogenous lithium as a potentially modifiable early event in Alzheimer pathogenesis, providing a mechanistic basis for lithium's neuroprotective potential. Randomized evidence from longer duration trials supports this, though a confirmatory trial is needed. For patients with BD, lithium is already indicated for mood stabilization. Long-term use may additionally offset the elevated dementia risk BD confers.