Early nucleus basalis of Meynert degeneration predicts cognitive decline in Parkinson's disease

Abstract

This scientific commentary refers to ‘In vivo cholinergic basal forebrain atrophy predicts cognitive decline in de novo Parkinson’s disease’ by Ray et al. (doi:10.1093/brain/awx310).

Figure 1

Schematic of anatomy of the nucleus basalis of Meynert (NBM) and risk factors for cognitive decline and dementia in Parkinson’s disease. (A) 3D representation of the anatomy of the NBM. Left: The medial surface of the left hemisphere of the human brain is closest to the viewer. The NBM is the green structure located in the basal forebrain inferior to the globus pallidus internus (GPi). The green arrows emanating from the NBM represent its corticopetal projections passing in the medial and lateral cholinergic pathways to all cortical areas. A = amygdala; C = caudate; P = putamen; T = thalamus. Right: The inset shows a 3D representation of the NBM itself. It is an elongated flat structure spanning 13–14 mm in the sagittal plane. The posterior subsector of the nucleus termed ‘Ch4p’ is highlighted. The brown nucleus below represents an atrophic NBM, reduced in size compared to its previous intact form (represented in translucent green). (B) Model showing all the clinical features and biomarkers which have been shown to be predictive of cognitive decline and future dementia in Parkinson’s disease. Those in green boxes all have a putative cholinergic basis, while those in yellow boxes represent non-cholinergic factors. The green arrows highlight the fact that degeneration of the NBM plays a major role in development of the linked predictive clinical features. Aβ₄₂ = amyloid-β₄₂; DAT = dopamine active transporter scan; REM = rapid eye movement.