Abstract

Age-related neuropsychiatric disorders pose significant challenges to global healthcare systems, impacting millions of individuals worldwide. Among the various neurotransmitter systems implicated in these disorders, the noradrenergic and cholinergic systems have emerged as central players due to their widespread distribution and critical roles in cognitive and emotional regulation. This paper reviews the current understanding of the involvement of noradrenergic and cholinergic neurotransmission in age-related neuropsychiatric disorders, including Alzheimer's disease, Parkinson's disease, and late-life depression. We discuss the anatomical and functional aspects of these systems, their interactions, and the therapeutic implications for targeting them in the treatment of these debilitating conditions. Among the various neurotransmitter systems implicated in age-related neuropsychiatric disorders, the noradrenergic and cholinergic systems have emerged as central players due to their widespread distribution and critical roles in cognitive and emotional regulation. The noradrenergic system, originating from the locus coeruleus (LC) in the brainstem, modulates diverse functions, including attention, arousal, mood, and stress response. Dysfunction of noradrenergic pathways has been implicated in cognitive decline and behavioral symptoms across AD, PD, and LLD. Similarly, the cholinergic system, originating from the basal forebrain nuclei, is crucial for cognitive functions such as memory, learning, and attention. Cholinergic deficits, resulting from degeneration of cholinergic neurons in AD and alterations in other neuropsychiatric disorders, contribute significantly to cognitive impairment and mood dysregulation