Malnutrition a predictor of cognitive decline in seniors

Older people at risk of malnutrition are more likely to develop cognitive decline than those with sufficient nutrition, suggest findings from the Singapore Longitudinal Ageing Studies (SLAS).

“The ENIGMA* measure of global malnutrition risk predicts cognitive decline and incident neurocognitive disorders, suggesting the feasibility of identifying vulnerable subpopulations of older adults for correction of malnutrition risk to prevent neurocognitive disorders,” said the researchers led by Dr Ng Tze Pin from Yong Loo Lin School of Medicine, National University of Singapore.

The longitudinal population-based study included 3,128 community-dwelling Chinese older individuals aged ≥55 years in Singapore. Participants were assessed on nutritional status at baseline using ENIGMA and followed up on cognitive decline and incident neurocognitive disorders in the subsequent 3–5 years. [J Nutr Health Aging 2021;25:660-667]

Older people at global risk of malnutrition, as identified based on ENIGMA risk score of ≥3, were 1.6 times more likely to develop cognitive decline (defined as MMSE** drop of ≥2). Similarly, the risk of incident neurocognitive disorders, including mild cognitive impairment (MCI) or dementia, was raised by 2.3 times in these individuals.

The risk remained elevated after controlling for multiple potential confounders including demographic, clinical, and behavioural factors. Individuals with high nutritional risk have 42 percent and 64 percent increased likelihood of developing cognitive decline (adjusted odds ratio [OR], 1.42, 95 percent confidence interval [CI], 1.01–1.99) and incident neurocognitive disorders (OR, 1.64, 95 percent CI, 1.03–2.59), respectively.

“The ENIGMA includes four [food] question items … indicating food insecurity and reduced quantity and quality of food intake and absorption, which are recognized risk factors for malnutrition, and four blood indicators … which assess negative nitrogen balance, inflammatory activity and impaired immune host response,” explained Ng and co-authors.

The four food question items were physically unable to feed or shop and cook for oneself, feeding difficulty due to oral issue, consumption of few fruits/vegetables/dairy products, and polypharmacy; whereas the four blood indicators included: low levels of albumin, total cholesterol, haemoglobin, and lymphocytes counts.

In particular, having low albumin at baseline was associated with a significantly heightened risk of both cognitive decline (OR, 1.44; p<0.01) and incident neurocognitive disorders (OR, 1.38; p<0.05).

Additionally, other component indicators of ENIGMA such as low intake of fruits/vegetables/dairy products, polypharmacy, and low total cholesterol were also associated with incident neurocognitive disorders.

“Eating few fruits, vegetables or milk products [is] a direct measure of food insecurity and reduced nutrient intake,” said the researchers.

They believed that the underlying mechanism mediating the association between malnutrition and neurocognitive disorders could be attributed to inflammation, which could lead to synaptic dysfunction and death of neurons in the brain.

Apart from malnutrition, the researchers also pointed out that another factor to watch out for is weight loss.

“Among patients with Alzheimer’s disease, significant weight loss is commonly present, and predicts rapid cognitive decline, but may be prevented by adequate nutritional care,” said Ng and co-authors. “When weight loss occurs some years before the onset of symptoms or signs of cognitive impairment, it may be a risk factor for dementia due to macronutrient or micronutrient deficiency.”

*ENIGMA: Elderly Nutritional Indicators for Geriatric Malnutrition Assessment
**MMSE: Mini Mental State Examination