Effect of resistance-type exercise training with or without protein supplementation on cognitive functioning in frail and pre-frail elderly: Secondary analysis of a randomized, double-blind, placebo-controlled trial

•Exercise is one of the most effective strategies to prevent cognitive decline.•First trial in frail elderly examining exercise effect on cognitive function.•Including examination of additional effect of protein supplementation on cognition.•Exercise training alone was beneficial for attention and working memory.•Exercise plus protein supplementation improved information processing speed. Physical activity has been proposed as one of the most effective strategies to prevent cognitive decline. Protein supplementation may exert an additive effect. The effect of resistance-type exercise training with or without protein supplementation on cognitive functioning in frail and pre-frail elderly people was assessed in a secondary analysis. Two 24-week, double-blind, randomized, placebo-controlled intervention studies were carried out in parallel. Subjects performed a resistance-type exercise program of two sessions per week (n=62) or no exercise program (n=65). In both studies, subjects were randomly allocated to either a protein (2×15g daily) or a placebo drink. Cognitive functioning was assessed with a neuropsychological test battery focusing on the cognitive domains episodic memory, attention and working memory, information processing speed, and executive functioning. In frail and pre-frail elderly, resistance-type exercise training in combination with protein supplementation improved information processing speed (changes in domain score 0.08±0.51 versus −0.23±0.19 in the non-exercise group, p=0.04). Exercise training without protein supplementation was beneficial for attention and working memory (changes in domain scores 0.35±0.70 versus −0.12±0.69 in the non-exercise group, p=0.02). There were no significant differences among the intervention groups on the other cognitive tests or domain scores.