Decreased Brain-Derived Neurotrophic Factor in Older Adults with Bipolar Disorder.

Objectives Decreased levels of brain derived neurotrophic factor (BDNF) have been found in adult patients with bipolar disorder (BD) compared with a comparison group, yet there are no data specifically examining this in geriatric patients. The objective of this study was to examine whether euthymic late-life BD patients have lower BDNF levels than healthy comparators. Design Cross-sectional study. Setting Clinics at the University of Pittsburgh and the Centre for Addiction and Mental Health (Toronto). Participants Older patients with BD (age ≥ 50 years, N = 118) and similarly aged healthy comparators (N = 76). There were both BD type I (N = 91) and type II (N = 27) patients. Measurements Serum BDNF levels were assessed in BD patients and healthy comparators. Results We found lower levels of BDNF in patients with BD than in healthy comparators (9.0  ±  6.2 versus 12.3  ±  8.9 pg/µg, t (192)  = −3.01, p = 0.002), which remained even after controlling for age, sex, lithium use, and site (F (1,176)  = 4.32, p = 0.039). This decrease was found specifically in patients with BD type I (8.0  ±  5.5 versus 12.3  ±  8.9 pg/µg, t (165)  = 3.7, Bonferroni p   0.001), but not type II (12.0  ±  7.5 versus 12.3  ±  8.9 pg/µg, t (101)  = 0.14, Bonferroni p = 1.0). Conclusions Older patients with BD have lower serum levels of BDNF compared with similarly aged comparators. These effects appear to be specific to patients with BD type I. Future studies are needed to investigate the impact of reduced BDNF levels on cognition, mood, and other aspects of BD throughout the life course.