The nucleus basalis of Meynert: a new target for deep brain stimulation in dementia?

Dementia is a major cause of disability amongst the elderly and represents a serious global health issue. Current treatments for dementia are limited; at best they provide inadequate symptomatic relief. In contrast, there are a plethora of approaches that provide symptomatic relief for abnormalities of movement including surgical approaches. Deep brain stimulation has been used successfully to directly alter processing in neural networks and thereby improve movement functions. Here we describe the anatomy, intrinsic organization and connectivity of the cholinergic nucleus basalis of Meynert, a basal forebrain structure implicated in cognitive functions including memory, attention, arousal and perception. A significant body of evidence suggests that degeneration of the nucleus and its cortical projections underlies the cognitive decline seen in dementia. We review this evidence and postulate that deep brain stimulation to this nucleus may be able to improve specific cognitive functions. This could represent a novel treatment strategy for some dementias in carefully selected individuals. Controlled trials of deep brain stimulation of the nucleus basalis of Meynert for Parkinson's disease dementia and Alzheimer's disease are required to evaluate potential efficacy and the mechanisms of possible cognitive changes.