- Major Neurocognitive Disorder (MaND)
- The DSM-5 term replacing "dementia." Involves significant cognitive decline from a prior level in one or more domains (memory, executive function, language, etc.) that interferes with independence in everyday activities.
- Mild Neurocognitive Disorder (MiND)
- Modest cognitive decline that does not interfere significantly with daily independence. Replaces the term "mild cognitive impairment." Approximately 10–15% of cases progress to MaND per year, but many remain stable or revert to normal.
- Delirium
- An acute, fluctuating disturbance of attention and awareness caused by an underlying medical condition, substance intoxication/withdrawal, or medication. Distinguished from dementia by its acute onset and fluctuating course. Common in hospitalised older adults.
- Amyloid-beta (Aβ) plaques
- Extracellular deposits of misfolded amyloid-beta protein — a hallmark of Alzheimer's disease. The amyloid cascade hypothesis proposes that Aβ accumulation initiates a chain of events leading to neurodegeneration, though the relationship between plaques and symptoms is complex.
- Neurofibrillary tangles (tau)
- Intracellular aggregates of hyperphosphorylated tau protein, another neuropathological hallmark of Alzheimer's disease. Tau tangles correlate more closely with cognitive decline than amyloid plaques. Tauopathies (e.g., frontotemporal dementia) can occur independently of amyloid pathology.
- Lewy bodies
- Abnormal intracellular aggregates of alpha-synuclein protein found in neurons. The defining pathology of Dementia with Lewy Bodies (DLB) and Parkinson's disease dementia. Associated with the clinical triad of fluctuating cognition, visual hallucinations, and Parkinsonism.
- Cholinergic hypothesis
- The proposal that the cognitive symptoms of Alzheimer's disease result substantially from loss of cholinergic neurons in the basal forebrain (nucleus basalis of Meynert). This hypothesis underpins the use of acetylcholinesterase inhibitors (e.g., donepezil) as symptomatic treatments.
- Vascular dementia
- The second most common dementia, caused by cerebrovascular disease (strokes, small vessel disease, white matter lesions). Often shows a stepwise rather than gradual decline. Risk factors overlap with cardiovascular disease (hypertension, diabetes, smoking).
- Frontotemporal dementia (FTD)
- A group of dementias characterised by progressive degeneration of the frontal and temporal lobes. Typically presents with personality change, disinhibition, apathy, or language impairment rather than memory loss. Often affects younger adults (40s–60s).
- Acetylcholinesterase inhibitors
- Drugs (e.g., donepezil, rivastigmine, galantamine) that prevent breakdown of acetylcholine, increasing its availability. Used symptomatically in mild-to-moderate Alzheimer's disease and DLB. Produce modest improvements in cognition and function but do not halt disease progression.