We evaluated the association between nutritional status and cognitive functioning in 260 noninstitutionalized men and women older than 60 years who had no known physical illnesses and were receiving no medications. Nutritional status was evaluated by three-day food records and also by biochemical determination of blood levels of specific nutrients. Cognitive status was evaluated by the Halstead-Reitan Categories Test (a nonverbal test of abstract thinking ability) and by the Wechsler Memory Test. Subjects with low blood levels of vitamins C or B12 scored worse on both tests. Subjects with low levels of riboflavin or folic acid scored worse on the categories test. These differences remained significant after controlling for age, gender, level of income, and amount of education. “Subclinical” malnutrition may play a small role in the depression of cognitive function detectable in some elderly individuals, or depressed cognitive function may result in reduced nutrient intake.

Goodwin JS, Goodwin JM, Garry PJ. Association between nutritional status and cognitive functioning in a healthy elderly population. JAMA. 1983 Jun 3;249(21):2917-21. PMID: 6842805.