by Karolinska Institutet

Eating healthier may reduce cognitive decline and diminish the negative impact of an unhealthy diet on memory and thinking abilities in older adults, suggests a new study by researchers at Karolinska Institutet. The findings are being published online by the journal Alzheimer's & Dementia.

"Most people eat a combination of healthy and less healthy foods, but we know little about how a mix of dietary patterns may impact cognitive function," says study author Behnaz Shakersain, doctoral student at the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, and also affiliated to the Aging Research Center in Stockholm. "In our study population, we saw evidence that those who mostly consumed an unhealthy diet had approximately twice as much cognitive decline than those who consumed healthy and unhealthy diets together over time."

The study analyzed the diets of 2,223 Swedish adults aged 60 or older and compared this information with their cognitive function over a six-year period. All individuals were dementia-free at the start of the study and underwent cognitive testing at the start and again after three years and six years. Cognitive abilities were measured using the Mini-Mental State Examination, which is frequently used in research settings and by health care professionals to screen for dementia and is scored from 0 to 30.

Different food and beverage items

A questionnaire given at the beginning of the study asked participants how often nearly 100 different food and beverage items were consumed over the previous 12 months. The researchers used the responses to group participants by how strongly they adhered to a "Western" pattern diet (red/processed meat, saturated/trans-fat, refined grains, sugar, beer, and spirits) and a "prudent" pattern diet (vegetables, fruits, cooking/dressing oil, cereals and legumes, whole grains, rice/pasta, fish, low-fat dairy, poultry, and water).

The results show that people with the highest adherence to the "prudent" diet and the least adherence to the "Western" diet, labeled as the "high protection, low risk group," experienced the smallest decline in cognitive function over time. Individuals in the study with the least adherence to the "prudent" diet and the highest adherence to the "Western" diet, labeled as the "low protection, high risk group," showed a statistically significant increase in cognitive decline with an average of more than 1 point decline in general cognitive test score over time compared to those in the "high protection, low risk group."

More information: Behnaz Shakersain et al. "Prudent diet may attenuate the adverse effects of Western diet on cognitive decline," Alzheimer's & Dementia (2015). DOI: 10.1016/j.jalz.2015.08.002

Provided by Karolinska Institutet