Structural and microstructural brain changes predict impairment in daily functioning

Brain changes on magnetic resonance imaging (MRI) reflect accumulating pathology and have clinically disabling consequences, such as dementia. However, little is known on the relation of these MRI markers with daily functioning in nondemented individuals. We investigated whether structural and microstructural brain changes are associated with impairment in activities of daily living in a community-dwelling population.

Between 2005 and 2009, 2025 stroke-free nondemented participants (aged 59.9 years) from the population-based Rotterdam Study underwent brain MRI, yielding global MRI markers, focal MRI markers, and microstructural MRI markers. We used the Stanford Health Assessment Questionnaire to assess basic activities of daily living, and the Instrumental Activities of Daily Living Scale to assess instrumental activities of daily living. Follow-up on activities of daily living was obtained between 2008 and 2013 (mean follow-up 5.7 years). We used linear regression to analyze continuous scores of daily living and logistic regression for incident impairment.

Eighty-two participants became impaired in basic and 33 in instrumental activities of daily living. Smaller brain and hippocampal volume and higher diffusivity were associated with larger change in activities of daily living. Smaller brain volume (odds ratio [OR] 4.05 per SD; 95% confidence interval [CI], 1.81-9.02), larger white matter lesion volume (OR 1.33/SD; 95% CI 1.02-1.72) and higher mean (OR 1.55/SD; 95% CI, 1.11-2.15), axial (OR 1.49/SD; 95% CI, 1.08-2.07), and radial diffusivity (OR 1.51/SD; 95% CI, 1.09-2.10) were associated with higher risk of impairment in basic activities of daily living.

In community-dwelling individuals, brain changes are associated with deterioration and incident impairment in daily functioning.