The impact of malnutrition on cognition in older adults: A systematic review

There is a lack of evidence to support the hypothesis that malnutrition may promote cognitive decline. This study aimed to explore the available literature on this topic.

A systematic review was undertaken of studies investigating the effect of nutritional status on cognitive function in adults of any age, using Medline, Embase, PsycINFO and Global Health via OvidSP from earliest available dates to January 2024. Studies were excluded if they were conducted in animal or paediatric populations, or if they did not include measurements of baseline nutritional status or follow-up assessment of cognitive function. Selected studies were assessed for quality, and data extracted. A meta-analysis was not conducted due to the heterogeneity of the data.

A total of nine studies (three randomised and six observational) was retrieved, including total 8697 subjects who were all in older age groups. Study quality was generally poor. Seven of the nine studies supported the hypothesis that baseline nutritional status is predictive of change in cognitive function at later assessment, but all studies failed to control for significant confounders and six of the nine had large amounts of missing data at follow-up, so that it remains unclear whether nutrition is independently associated with later cognitive function.

Malnutrition may be associated with subsequent development of cognitive dysfunction in older adults. Higher quality studies in a wider range of age groups are needed to investigate whether nutritional status has an independent impact on cognitive function, and whether this is related to specific nutrient deficiencies.