Caudate volume and symptoms of apathy in older adults with multiple sclerosis

Apathy is common in multiple sclerosis (MS) and neurological disease, but its presence and underlying brain mechanisms in older adults with MS (OAMS) have not been evaluated.

Examine apathy and its association with caudate nuclei volume in OAMS and controls. We hypothesized that compared to controls, OAMS would demonstrate: a) greater apathy; b) stronger associations between apathy and caudate nuclei volumes.

OAMS (n = 67, mean age = 64.55 ± 3.89) and controls (n = 74, mean age = 69.04 ± 6.32) underwent brain MRI, cognitive assessment, psychological, and motoric testing. Apathy was assessed through the apathy subscale of the 30-item Geriatric Depression Scale.

OAMS reported greater apathy compared to controls (β = 0.281, p = 0.004). Adjusted moderation analyses revealed a significantly stronger association between caudate volume and apathy (left: B = -1.156, p = 0.039, right: B = -1.163, p = 0.040) among OAMS compared to controls. Conditional effects revealed that in adjusted models, lower volume of both the left (b = -0.882, p = 0.037) and right (b = -0.891, p = 0.038) caudate nuclei was significantly associated with greater apathy only among OAMS.

Caudate nuclei, which are susceptible to adverse MS effects and implicated in mediating cognitive and motor function, may influence the presence and severity of apathy in OAMS.