Effects of physical exercise on cognitive impairment in patients with Alzheimer's disease, Parkinson's disease or mild cognitive impairment: a systematic review and meta-analysis.

BACKGROUND: Neurodegenerative disorders impose a major burden on patients and their families worldwide, and finding effective ways to treat or prevent these disorders is essential but challenging. In recent years, physical exercise interventions have attracted considerable attention as a potential approach to modify cognitive decline, which is a major shared symptom of these disorders. In this systematic review and meta-analysis, we focused on studies investigating the effectiveness of physical exercise interventions for various cognitive domains in patients with Alzheimer’s disease (AD), Parkinson’s disease (PD) or mild cognitive impairment (MCI), who presented with initial cognitive deficits. METHODS: We performed a systematic literature search in PubMed, Embase and CENTRAL for randomized controlled trials (RCTs) published in English until October 2025. We considered them eligible when they investigated the effects of physical exercise on cognitive functioning in AD, PD or MCI patients who all already had cognitive deficits before the start of the study. A random-effects model was applied to explore the effects of physical exercise on four main cognitive domains: global cognition, executive function, memory and attention. RESULTS: In total, 28 RCTs were eligible for inclusion in this review (AD n = 8; MCI n = 16; PD n = 4). Patient subgroup analyses revealed that physical exercise significantly improved global cognition, executive function, memory and attention in both the MCI and AD patient groups, whereas no significant effects were observed in PD patients. CONCLUSIONS: These findings indicate that exercise-related benefits extend across multiple cognitive domains in AD and MCI patients and support its potential as a non-pharmacological strategy for individuals with neurodegenerative disorders. In PD, evidence remains limited and inconclusive. Despite substantial variability in exercise interventions, consistent effects were observed, suggesting that cognitive benefits may be broadly applicable across different modalities. However, the limited number of studies including patients with objectively verified cognitive impairment, particularly in PD, as well as the focus on global cognition in many AD studies, highlight important gaps in the current literature. Future research should specifically target cognitively impaired populations and include sufficiently large and well-characterized samples to improve the precision and clinical applicability of the evidence.