A randomized controlled trial of dietetic interventions to prevent cognitive decline in old age hostel residents

To examine whether dietary interventions promote intakes of fruit, vegetable, fish and lower salt intake were effective in preventing cognitive decline in older people. Dietary factors have been associated with cognitive function in older people.

A total of 429 non-demented subjects in 14 old age hostels, with an average age of 83 years, were randomly assigned by hostel to have either regular group dietary counselling and menu changes or advice on hostel menu only. Food and salt intakes were estimated at regular intervals by 24-h recall or food record and fasting urinary sodium, respectively. The primary outcome was cognitive decline as defined by an increase in clinical dementia rating scale score. Secondary clinical outcomes were mini mental state examination, category fluency test, body weight, blood pressures and health-related quality of life.

At baseline, the intervention group had more men and lower fish intake. When compared with control group, the intervention group had significantly less decline in intakes of fruit and fish. At month 33%, 22.2% and 27.2% of intervention and control group subjects had cognitive decline, respectively (Unadjusted P=0.285, χ² test). There were no significant group changes in secondary clinical outcomes. On subgroup analysis, fewer cognitively normal subjects in intervention group had cognitive decline at month 24 (adjusted P=0.065).

Dietary interventions in older people were effective in maintaining fruit and fish intake, but this did not lead to a significant reduction in cognitive decline.