A Healthy Diet Is Linked to Better Cognitive Performance in Seniors

Source: Tufts University
February 25, 2002 (Reviewed: February 23, 2004)

A recent study published in the European Journal of Clinical Nutrition found a healthful diet to be associated with better cognitive performance in an elderly population.

The role of diet in mental performance

Cognitive performance, including memory, spatial orientation, and executive function ability, is known to decline with age, and many studies have investigated the role diet may play in delaying or preventing this decline. New evidence derived from the analysis of data from an existing study of dementia strengthens the evidence of a link between diet and mental decline.

Researchers in Italy analyzed data from a population-based prevalence study of senile dementia conducted during 1992 and 1993 among residents of four rural towns. The study included everybody aged 70 and older, as well as a random sample (40%) of people aged 65-69.

A total of 1,651 subjects were studied (560 men and 1,091 women). The mean age of the population was 76.7 years (74.9 for men and 77.5 for women).

Defining a healthy diet

Dietary information was obtained using a 180-item food frequency questionnaire and nutrient intake was calculated using the food composition database compiled for epidemiologic studies in Italy.

A healthy diet was defined based on the World Health Organization (WHO) recommendations for the prevention of chronic diseases. Diets were scored for how well they adhered to recommended intakes of the following variables:

Dietary variable	Recommended intake
Saturated fat	</= 10% total energy intake
Polyunsaturated fat	3-7% total energy intake
Protein	10-15% total energy intake
Polysaccharides	50-70% total energy intake
Fiber	27-40 g/day
Vegetables and fruits	> 400 g/day
Pulses and nuts	> 30 g/day
Oligosaccharides	</= 10% total energy intake
Cholesterol	</= 300 mg/day

Measuring cognitive performance

Cognitive performance was measured using a 70-point neuropsychological test (NPT), which was an extended and validated version of the Mini Mental State Examination. More than 30% of the men and almost 48% of the women studied had some kind of cognitive deficit, with the women having a higher crude prevalence of mild or moderate cognitive impairment.

After adjusting for age, sex, education, total energy intake, cigarette smoking, alcohol consumption, and physical activity, a better healthy diet score was associated with a lower prevalence of cognitive deficit (OR = 0.85; 95% CI 0.77-0.93).

Further research necessary

While these results are interesting, there are important limitations to this study. The most significant of them may be the questionable accuracy of data obtained by administering food frequency questionnaires to elderly people, some of whom had cognitive impairment.

It is also difficult to determine if certain aspects of the "healthy diet" were more protective than others. While the researchers contend that that the total diet is likely responsible for the observed association, specific foods or nutrients could be responsible for the difference.

Although a healthful diet cannot yet be said to protect against mental decline, the many other benefits of such a diet make it an important recommendation for adults of all ages.

Source

• Nutrition and cognitive deficit in the elderly: a population study. ML. Corrêa, A. Nicolosi, S. Cristina,  et al., Eur J Clin Nutr., 2001, vol. 55, pp. 1053--1058

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