Regional atrophy and hypoperfusion mediate the association between affective symptoms and cognitive impairment in Alzheimer's disease.

Objective

Affective symptoms are common and associated with poor cognitive outcomes in patients with Alzheimer's disease (AD); however, their underlying neural correlations remain poorly understood.

Methods

This study included 105 patients with AD. Patients were classified into an AD with affective symptoms (AD-A) group and an AD without affective symptoms (AD-NA) group according to scores obtained on the depression and anxiety items of the Neuropsychiatric Inventory. All of the participants underwent neuropsychological assessments and multimodal magnetic resonance imaging (MRI) scans.

Results

Compared with the AD-NA group, the AD-A group was younger and exhibited more severe, widespread cognitive impairments. Neuroimaging revealed that the AD-A group exhibited reduced grey matter volume (GMV) in the bilateral posterior cerebellum and right fusiform gyrus, along with reduced global cerebral blood flow (CBF) and lower CBF in the left parieto-temporo-occipital region. Mediation analyses revealed significant indirect associations between affective symptoms and cognitive function via cerebellar GMV and left parieto-temporo-occipital CBF.

Conclusion

Cerebellar structural atrophy and left parieto-temporo-occipital hypoperfusion are associated with both affective symptoms and cognitive impairment and may represent neural correlates of the affective-cognitive association in AD patients.