Longer lithium exposure is associated with better white matter integrity in older adults with bipolar disorder.

Objectives: Bipolar disorder (BD) is associated with cognitive dysfunction and structural brain abnormalities. In human and non-human studies, lithium has been related to neuroprotective and neurotrophic effects. We explored whether lithium treatment is related to better brain integrity and cognitive function in older adults with BD.

Methods: We examined cognitive and neuroimaging data in 58 individuals with BD [mean (standard deviation) age = 64.5 (9.8) years] and 21 mentally healthy comparators (controls) of similar age and education. Subjects received comprehensive neurocognitive assessment and structural brain imaging, examining total gray matter volume, overall white matter integrity (fractional anisotropy), and total white matter hyperintensity burden.

Results: In comparison to controls, subjects with BD had worse overall cognitive performance, lower total gray matter volume, and lower white matter integrity. Among subjects with BD, longer duration of lithium treatment was related to higher white matter integrity after controlling for age and vascular disease burden, but not with better cognitive performance.

Conclusions: Lithium treatment appears to be related to better brain integrity in older individuals with BD, in particular, in those who take lithium long-term. While intriguing, these findings need to be confirmed in a larger sample.