Structural and Functional Projections of the Nucleus Basalis of Meynert and Their Changes After Cognitive Training in Individuals With Mild Cognitive Impairment.

AIMS

The nucleus basalis of Meynert (NBM) is a major source of cholinergic innervation in the central nervous system. We aimed to investigate the characteristics of structural and functional alterations in the NBM and its projections in patients with mild cognitive impairment (MCI) and the effects of computerized cognitive training (CCT).

METHODS

Forty-five patients with MCI and 45 cognitively unimpaired controls (CUCs) were recruited. NBM volume, mean diffusivity (MD) of NBM white matter (WM) projections, and functional connectivity (FC) of projections of the NBM were measured with T1-weighted imaging, diffusion tensor imaging (DTI), and resting-state functional magnetic resonance imaging (rs-fMRI). Thirty-six MCI patients were randomly assigned to receive CCT or control training. The effects of CCT on the neuropsychological measures and MRI properties were analyzed with a linear mixed model (LMM).

RESULTS

We detected that compared with the CUCs, the MCI patients had a reduced volume of the NBM and a greater MD of both cholinergic pathways. Increased MD values of both pathways were related to lower scores of global cognition, processing speed and attention in all participants. After CCT intervention, significant group × timepoint effects on score of the Backward Digit Span and the FC between NBM and right putamen were observed in the CCT group compared to the control group.

CONCLUSION

NBM atrophy and WM pathway disruption occurred in MCI patients and were correlated with cognitive impairment. Working memory and the FC between NBM and right putamen could be improved by cognitive training.