We aim to test the association between brain magnetic resonance imaging (MRI) volumes and lesions – and their change over time – in individuals with cognitive and gait speed decline.

A sample of 385 participants was derived from the Swedish National Study on Aging and Care in Kungsholmen. Brain MRI markers included volumes of total brain tissue, hippocampus (HV), lateral ventricles and white matter hyperintensities (WMH). Cognition was assessed through the Mini Mental State Examination (MMSE) and physical function through gait speed (m/s). Based on the decline pattern over 12 years, estimated with linear mixed models, participants were divided into four groups: non-decliners (reference group), fast decliners only in cognition, fast decliners only in gait speed and fast decliners in both cognition and gait speed. Multinomial logistic regression was used to test the association between baseline brain data and the speed of decline over time. Linear mixed models were used to estimate the association between changes in brain MRI measures and the speed of decline in cognition and gait speed.

A smaller total brain tissue volume (p=.002) and HV (p=.013), and a greater load of WMH (p=.015) and ventricles volumes (p<.001) were associated with a faster decline in both cognition and physical function as compared with non-decliners. We observed a greater loss in the total brain tissue volume (β:-12.1;95%CI:-18.1;-6.0), a smaller HV (β:-0.13;95%CI:-0.17;-0.08), a greater accumulation of WMH (β:1.54;95%CI:0.48;2.59) and greater ventricular volumes (β:2.07;95%CI:0.70;3.43), as compared to non-decliners.  

Smaller brain volumes and more lesions, together with loss of neural integrity over time, predicts faster and simultaneous decline in cognition and gait speed.