Add-on memantine may improve cognitive functions and attenuate inflammation in middle- to old-aged bipolar II disorder patients.

OBJECTIVES

Chronic inflammation and neuroprogression underlie bipolar disorder (BP) and associated cognitive deficits. Memantine (MM) exerts neuroprotective effects by reducing neuroinflammation. Therefore, we investigated whether add-on low-dose MM (5 mg/day) in BP-II patients may improve cognition and inflammation.

METHODS

We combined two 12-week randomized, double-blind, placebo-controlled studies (NCT01188148 and NCT03039842) for analysis. Each participant was allocated to the MM or placebo group. Symptom severity, neuropsychological tests, and the cytokine plasma levels [tumor necrosis factor-α (TNF-α), C-reactive protein (CRP), interleukin-8 (IL-8), transforming growth factor-β1 (TGF-β1), and brain-derived neurotrophic factor (BDNF)] were evaluated at baseline and endpoint. A subgroup analysis of middle- to old-aged BP-II patients was also performed.

RESULTS

We recruited 155 BP-II patients (23 of which were middle- to old-aged) for the MM group and 170 patients (20 of which were middle- to old-aged) for the placebo group. Add-on MM did not result in significant improvements in cognitive functions in all BP-II patients, but a group difference in TNF-α levels was found in the MM group (P=0.04). Specifically, in middle- to old-aged BP-II patients, there was a significant time and group interaction effect on omission T-scores, hit reaction time T-scores, and hit reaction time standard error T-scores on continuous performance tests (CPTs) in the MM group (P=0.007, 0.02, and 0.01, respectively), and a decrease in plasma TNF-α levels (P=0.04).

LIMITATIONS: The sample size of middle- to old-aged BP-II patients were limited.

CONCLUSION

Add-on MM may attenuate inflammation in BP-II and improve cognition in middle- to old-aged BP-II patients.