Effect of physical exercise on cognitive function in older adults' carriers versus noncarriers of apolipoprotein E4: systematic review and meta-analysis

The presence of apolipoprotein (Apo) E4 is a genetic risk factor in cognitive impairment Physical exercise contributes to slowing cognitive impairment in older adults, but little is known about the influence of exercise on ApoE4 carriers and noncarriers. The objective of systematic review is to study the role of physical exercise in older adults' ApoE4 carriers and noncarriers. A systematic literature search was carried out in five international databases: PubMed, Web of Science, PeDro, Scopus, and SPORTDiscus. A total of nine randomized controlled trials were included with a sample size of 2,025 subjects (901 ApoE4 carriers). The exercise reported a significant improvement on cognitive performance in older adults ApoE4 noncarriers (standardized mean difference ESMDJ= 0.653; 95% confidence interval [CI] 0.29-1.00; chi(2) = 35.36; degrees of freedom [df]=7; P< 0.0001; I-2 = 80%). It was also reported that a total program duration greater than 50 sessions generated different and significant effects on cognitive performance in older adults' ApoE4 noncarriers (SMD= 0.878; 95% CI, 0.14-1.61; chi(2) = 31.82; df=3; P< 0.0001; I-2 =91%). The results reported that high intensity generated a differential effect on cognitive performance in older adults' ApoE4 carriers versus noncarriers (SMD = 0.963; 95% CI, 0.25-1.67; chi(2) = 18.11; df= 3; P< 0.0004; I-2 = 83%). The effect of physical exercise on cognitive performance in older adults is conditioned by the presence or not of ApoE4.