Longer Term Effects of Diet and Exercise on Neurocognition: 1-Year Follow-up of the ENLIGHTEN Trial

Abstract

Objectives: To evaluate the longer term changes in executive functioning among participants with cardiovascular disease (CVD) risk factors and cognitive impairments with no dementia (CIND) randomized to a diet and exercise intervention.

Design: A 2 (Exercise) × 2 (Dietary Approaches to Stop Hypertension [DASH] eating plan) factorial randomized clinical trial.

Setting: Academic tertiary care medical center.

Participants: Volunteer sample of 160 older sedentary adults with CIND and at least one additional CVD risk factor enrolled in the ENLIGHTEN trial between December 2011 and March 2016.

Interventions: Six months of aerobic exercise (AE), DASH diet counseling, combined AE + DASH, or health education (HE) controls.

Measurements: Neurocognitive battery recommended by the Neuropsychological Working Group for Vascular Cognitive Disorders including measures of executive function, memory, and language/verbal fluency. Secondary outcomes included the Clinical Dementia Rating-Sum of Boxes (CDR-SB), Six-Minute Walk Distance (6MWD), and CVD risk including blood pressure, body weight, and CVD medication burden.

Results: Despite discontinuation of lifestyle changes, participants in the exercise groups retained better executive function 1 year post-intervention (P = .041) compared with non-exercise groups, with a similar, albeit weaker, pattern in the DASH groups (P = .054), without variation over time (P's > .867). Participants in the exercise groups also achieved greater sustained improvements in 6MWD compared with non-Exercise participants (P < .001). Participants in the DASH groups exhibited lower CVD risk relative to non-DASH participants (P = .032); no differences in CVD risk were observed for participants in the Exercise groups compared with non-Exercise groups (P = .711). In post hoc analyses, the AE + DASH group had better performance on executive functioning (P < .001) and CDR-SB (P = .011) compared with HE controls.

Conclusion: For participants with CIND and CVD risk factors, exercise for 6 months promoted better executive functioning compared with non-exercisers through 1-year post-intervention, although its clinical significance is uncertain. J Am Geriatr Soc 68:559-568, 2020.

Trial registration: ClinicalTrials.gov NCT01573546.

Keywords: Dietary Approaches to Stop Hypertension diet; cardiovascular risk; cognitive impairment no dementia; executive functioning; exercise.

Conflict of interest statement

Conflicts of interest: The authors have no conflicts of interest to report.

© 2019 The American Geriatrics Society.

Figures

Figure 1.

Consort chart showing participant flow from randomization to 1-year follow-up.

Figure 2.

Executive Function performance at Baseline (pre-Intervention), 6-months (post-Intervention), and 1-year follow-up across Exercise factor (AE alone and AE+DASH), non-exercise (DASH alone and HE) and DASH factor (DASH alone and AE+DASH) and non-DASH (AE alone hand HE), controlling for age, education, gender, race, Framingham Stroke Risk Profile, CVD medication burden, chronic anti-inflammatory use, baseline MoCA score, and baseline Executive function scores. Participants in the Exercise conditions (AE and AE+DASH) exhibited better performance on a global Executive function score (P = .041) compared to participants in the non-Exercise conditions (DASH and HE). A non-significant trend was observed for greater improvements in Executive function among participants in the DASH factor groups (DASH and AE+DASH) compared to non-DASH groups (AE and HE) (P = .054). Values for post-intervention (6-months post-randomization) and one-year post-intervention (18-months post randomization) were derived using least squares means from our repeated measures, mixed model analyses with adjustment for all covariates. Baseline values were derived using least squares means from simple linear regression using the same covariates as our primary mixed model.

Figure 3.

Modified Clinical Dementia Rating Scale (Sum of Boxes) at Baseline (pre-Intervention), 6-months (post-Intervention), and 1-year follow-up across Exercise factor (AE alone and AE+DASH), non-exercise (DASH and HE), DASH factor (DASH alone and AE+DASH) and non-DASH (AE and HE) groups, controlling for age, education, gender, race, Framingham Stroke Risk Profile, CVD medication burden, chronic anti-inflammatory use, baseline MoCA score, and baseline mCDR-SB scores. Participants in the Exercise conditions (AE alone and AE+DASH) exhibited better performance on the mCDR-SB scores (P = .027) compared to participants in the non-Exercise conditions (DASH alone and HE). A non-significant trend was observed for greater improvements in CDR-SB scores among participants in the DASH factor groups (DASH and AE+DASH) compared to non-DASH groups (AE and HE) (P = .054). Values for post-intervention and one-year post-intervention (18 months post-randomization) were derived using least squares means from our repeated measures, mixed model analyses with adjustment for all covariates. Baseline values were derived using least squares means from simple linear regression using the same covariates as our primary mixed model.