Objective: To examine the association between the integrity of the nucleus basalis of Meynert (NBM), cognition and everyday function in Parkinson’s disease (PD).

Background: Most PD patients experience cognitive impairment, albeit at variable rates and with variable expression. About 50% progress to Parkinson’s disease dementia (PDD) by 10 years post-diagnosis, so understanding the underlying neural changes is needed to improve prediction for those at greatest risk. Cholinergic integrity may be a key factor. The NBM is the principal source of cholinergic innervation in the cerebral cortex. Evidence of the association between NBM integrity and neuropsychological test scores is inconsistent; and we do not know the association with everyday cognitive function (activities of everyday living, ADL), loss of which is a prerequisite for a dementia.

Method: We acquired structural and diffusion-weighted magnetic resonance imaging for 102 patients with PD (63 male). Level-II neuropsychological testing and significant other interview confirmed a broad spectrum of normal cognition (N = 58) through PD-MCI (N = 32) and PDD (N = 12). Imaging was also obtained for 39 control participants (17 male). We extracted volumetric and diffusion tensor metrics from the NBM using SPM 12 Anatomy Toolbox. For PD patients, we assessed the association between NBM measures and, separately, global cognition, ADL, and motor impairment. Age and sex were entered as covariates in linear models.

Results: Neither NBM volume, fractional anisotropy (FA), nor mean diffusivity (MD) differed significantly between controls and the PD group. Within the PD group, however, NBM volume (b = 0.18, p = 0.04) and MD (b = -0.20, p = 0.01; FA, b = 0.06, p = 0.41), were significantly associated with a global measure across neuropsychological test performance. There was also a significant association between ADL and NBM volume (b = -0.22, p = 0.01) and FA (b = -0.24, p < 0.01; MD, b = 0.07, p = 0.39), but no association when the non-dementing patients were assessed (all p > 0.1). UPDRS part III scores showed no associations with any measure.

Conclusion: While NBM integrity is associated with performance on cognitive tests, it does not covary with ADL in non-dementing patients. Longitudinal study is required to establish the value of NBM integrity as a predictor of future dementia.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/parkinsons-disease-and-nucleus-basalis-of-meynert-integrity-cognition-and-everyday-function/