Clinical meaning
Dementia is an umbrella term encompassing multiple neurodegenerative diseases with distinct pathologies, clinical presentations, and management approaches. The NP must differentiate dementia subtypes because treatment and prognosis differ significantly. Alzheimer Disease (AD, 60-70%): Characterized by amyloid-beta plaque accumulation and neurofibrillary tau tangles causing progressive synaptic dysfunction and neuronal death. The cholinergic deficit in the nucleus basalis of Meynert drives early memory symptoms. Begins with episodic memory loss (hippocampal involvement), progresses to language, visuospatial, and executive dysfunction as neurodegeneration spreads cortically. Treatment: cholinesterase inhibitors (donepezil, rivastigmine, galantamine) for mild-to-moderate; add memantine for moderate-to-severe. Vascular Dementia (VaD, 15-20%): Results from cumulative cerebrovascular ischemia — multi-infarct, strategic single infarct, or chronic small vessel disease. Characterized by stepwise decline with periods of stability between vascular events. Executive dysfunction is prominent early (planning, organizing, problem-solving), memory is relatively preserved early. Imaging shows white matter hyperintensities, lacunar infarcts, or prior large vessel strokes. Treatment: aggressive cardiovascular risk factor management; cholinesterase inhibitors may have modest benefit. Lewy Body Dementia (DLB, 5-15%): Alpha-synuclein aggregates (Lewy bodies) in cortical and subcortical neurons. Core features include fluctuating cognition (good days...