Firth J, et al. - Researchers examined the links between maximal handgrip strength and cognitive performance in people with major depression or bipolar disorder and in healthy controls. Findings suggested that in individuals with and without major depression and bipolar disorder, handgrip strength could be associated with overall cognition. Muscular function could help assess neurocognitive impairment and could be a novel interventional outcome for targeting cognitive improvement.

Methods

• Researchers performed a multicenter, population-based study between February 13, 2005, and October 1, 2010, in the United Kingdom; they conducted a cross-sectional analysis of baseline data from 110,067 participants in the UK Biobank.
• They mailed invitations to approximately 9.2 million UK homes, recruiting 502,664 adults, aged 37 to 73 years.
• They identified individuals with major recurrent depression (moderate or severe) or bipolar disorder (type I or type II) and healthy controls (those with no indication of present or previous mood disorders) using clinically validated measures.
• They used handgrip dynamometry to measure muscular function.
• Assessment of cognitive functioning was performed using computerized tasks of reaction time, visual memory, number memory, reasoning, and prospective memory.
• The association between handgrip strength and cognitive performance was assessed using generalized linear mixed models, controlling for age, educational level, sex, body weight, and geographic region.

Results

• This study had 110,067 participants: 22,699 individuals with major depression (mean [95% range] age, 55.5 [41-68] years; 7,936 [35.0%] men), 1,475 with bipolar disorder (age, 54.4 [41-68] years; 748 [50.7%] men), and 85,893 healthy controls (age, 53.7 [41-69] years; 43,000 [50.0%] men).
• Significant positive associations (P < .001) between maximal handgrip strength and improved performance was seen in patients with major depression on all 5 cognitive tasks, including visual memory (coefficient, -0.146; SE, 0.014), reaction time (coefficient, -0.036; SE, 0.002), reasoning (coefficient, 0.213; SE, 0.02), number memory (coefficient, 0.160; SE, 0.023), and prospective memory (coefficient, 0.341; SE, 0.024).
• Healthy controls showed comparable results.
• Participants with bipolar disorder demonstrated a positive association of handgrip strength with improved visual memory (coefficient, -0.129; SE,0.052; P=.01), reaction time (coefficient, -0.047; SE, 0.007; P < .001), prospective memory (coefficient, 0.262; SE, 0.088; P=.003), and reasoning (coefficient, 0.354; SE, 0.08; P< .001).