Deep brain stimulation of the nucleus basalis of Meynert in neurodegenerative diseases with cognitive impairment: An update on evidence and mechanisms.

Current pharmacotherapy for neurodegenerative diseases is limited to providing symptomatic relief, instead of slowing or reversing disease progression. As a form of neuromodulation surgery, deep brain stimulation delivers electrical pulses through implanted electrodes in targeted brain regions and has been used to alleviate symptoms in neurodegenerative diseases. Depending on the precise targeting of neural modulation, deep brain stimulation is being explored for its potential to manage symptoms and improve overall quality of life in neurodegenerative diseases associated with cognitive impairment, such as Alzheimer's disease and dementia in Parkinson's disease. The nucleus basalis of Meynert, a critical component of the cerebral cholinergic system and the Papez circuit, is considered as a promising target for treating cognitive dysfunction in neurodegenerative diseases due to its essential role in regulating cognition, memory, and attention. However, the comprehensive mechanisms by which deep brain stimulation of nucleus basalis of Meynert affects neurodegenerative diseases with cognitive impairment remain largely uncharacterized. Nonetheless, various hypotheses and evidence from animal and clinical studies suggest mechanisms such as the modeulation of the cholinergic system, increased glucose metabolism and regional cerebral blood flow, neuroprotective effects, and the modulation of neural networks. In this review, we update the advances in research regarding the therapeutic effects and potential mechanisms of deep brain stimulation of nucleus basalis of Meynert on cognitive impairment in neurodegenerative diseases. Additionally, we examine the anatomy, connectivity, and physiological functions of the nucleus basalis of Meynert. Deep brain stimulation of nucleus basalis of Meynert may improve cognitive impairment in neurodegenerative diseases through multiple mechanisms; however, further larger-scale, multi-center clinical trials conducted at earlier disease stages are necessary to fully confirm its efficacy and safety.