Individually modifiable risk factors to ameliorate cognitive aging: a systematic review and meta-analysis

Abstract

A number of health and lifestyle factors are thought to contribute to cognitive decline associated with age but cannot be easily modified by the individual patient. We identified 12 individually modifiable interventions that can be implemented during midlife or later with the potential to ameliorate cognitive aging. For ten of these, we used PubMed databases for a systematic review of long-duration (at least 6 months), randomized, controlled trials in midlife and older adults without dementia or mild cognitive impairment with objective measures of neuropsychological performance. Using network meta-analysis, we performed a quantitative synthesis for global cognition (primary outcome) and episodic memory (secondary outcome). Of 1038 publications identified by our search strategy, 24 eligible trials were included in the network meta-analysis. Results suggested that the Mediterranean diet supplemented by olive oil and tai chi exercise may improve global cognition, and the Mediterranean diet plus olive oil and soy isoflavone supplements may improve memory. Effect sizes were no more than small (standardized mean differences 0.11–0.22). Cognitive training may have cognitive benefit as well. Most individually modifiable risk factors have not yet been adequately studied. We conclude that some interventions that can be self-initiated by healthy midlife and older adults may ameliorate cognitive aging.

Key words::

• COGNITION
• COGNITIVE ACTIVITY
• COGNITIVE AGING
• DEHYDROEPIANDROSTERONE
• FOLATE
• GINKGO BILOBA
• MENOPAUSAL HORMONE THERAPY
• ISOFLAVONES
• MEDITERRANEAN DIET
• MEMORY
• META-ANALYSIS
• MINDFULNESS
• OMEGA-3 FATTY ACIDS
• PHYSICAL EXERCISE
• SOCIAL ENGAGEMENT
• SYSTEMATIC REVIEW
• TAI CHI
• VITAMIN B12
• VITAMIN D

ACKNOWLEDGEMENTS

We thank Rachael Smith and Barbara C. Henderson for assistance with data verification.

Conflict of interest Philippe Lehert, Eef Hogervorst and Victor Henderson declare no conflict of interest for this study. Paulina Villaseca has received honoraria for lectures and for acting as a member of an Advisory Board for Glaxo Smith & Kline. Pauline Maki has served as a consultant for Noven, Abbott, and Pfizer.

Source of funding Supported by National Institutes of Health grants R01AG034639 and P50AG047366.

Supplementary materials available online

Table S1 Search terms used in PubMed searches

Table S2 Cognitive effects of individually modifiable factors, random-effects model

Table S3 Cognitive effects of individually modifiable interventions: general intelligence (non-memory) outcomes