# Associations between Diet Quality and Global Cognitive Ability across the Life Course: Longitudinal Analysis of the 1946 British Birth Cohort

## TL;DR

This study shows that better diet quality over a lifetime is linked to higher cognitive ability and lower dementia risk in old age.

## Contribution

The study reveals lifelong associations between diet quality and cognitive function using trajectory modeling in a birth cohort.

## Key findings

- Lower diet quality was linked to lower cognitive ability and higher dementia risk in later life.
- Higher diet quality was associated with better cognitive outcomes across the lifespan.
- Diet and cognitive trajectories were influenced by early-life factors like sex and social class.

## Abstract

Diet is a risk factor for later-life cognitive decline and dementia. The long-term relationship between diet quality and cognitive function is unknown.

This study investigated trends in diet quality and cognitive ability and their interrelationship across the life course.

Using data from the 1946 British Birth Cohort (n = 3059, 50.2% male), group-based trajectory modeling identified diet and cognitive trajectories from childhood to later adulthood, associations between those trajectories, and associations between diet trajectories and later indications of likely dementia. Healthy Eating Index-2020 scores were calculated from food recalls and diaries at ages 4, 36, 43, 53, and 60 to 64 y. Global cognitive ability percentile ranks were derived from tests of intellectual ability and cognitive function at ages 8, 11, 15, 43, 53, 60 to 64, and 68 to 69 y. Addenbrooke’s Cognitive Examination-III scores indicated likely dementia at age 68 to 69 y. Multinomial logit models determined early-life predictors of trajectory groups.

Three diet quality trajectories and 4 cognitive ability trajectories were identified. Sex, birth region, childhood social class, and leisure activities predicted trajectory group membership. In a joint trajectory model, the lowest cognitive ability group included mostly participants with lower (58%) or moderate (35%) diet quality. Conversely, the highest cognitive ability group included mostly participants with moderate (57%) and higher (36%) diet quality. The percentage of participants showing indications of likely dementia at age 68 to 69 y was 3.8% to 7.4% greater in the lower diet quality group compared with the moderate and higher groups, respectively.

Findings indicate a link between diet quality and cognitive ability across the life course and a higher chance of likely dementia in individuals with lower diet quality from childhood to later adulthood. Consistent dietary alignment with dietary guidelines over time may positively impact cognitive outcomes throughout life, but more longitudinal studies are needed to confirm these findings.