Classification of Dementias and Their Complex Treatment
1. Overview & Epidemiology
Definition (Gajdos / DSM-5-TR). Dementia = major neurocognitive disorder: an acquired, usually progressive decline from a previously attained level in one or more cognitive domains, severe enough to interfere with independence in everyday activities. The cardinal symptom is cognitive impairment ("memory, judgment, orientation, and cognition"; motor dysfunction appears at the end). Cognitive impairment is the cardinal symptom shared by the three core organic syndromes: delirium, dementia, amnestic disorders.
Why it matters (Gajdos).
- Background physiologic changes are treatable in 10–20% of cases when recognised at an early stage → screen for reversible causes.
- Suicide rate is high among the demented (especially when insight is partly preserved).
- Progression of irreversible dementia can be slowed when recognised at onset → early diagnosis = prevention.
Epidemiology by subtype (Gajdos + Kaplan):
| Type | Share of all dementias | Typical age | Key genetics/risk |
|---|---|---|---|
| Alzheimer's disease (AD) | 60–70% (Gajdos); ~10% prevalence in those 65+ in Hungary | 65+ | APOE ε4, Down syndrome, family history |
| Vascular dementia (VD) | ~20% worldwide; in Hungary ~20% MORE VD than AD (high cardiovascular burden) | 60–70 | Hypertension, AF, prior stroke, diabetes |
| Lewy body / Parkinson dementia | ~5–10% | 70+ | α-synuclein (Lewy bodies); sporadic mostly |
| Frontotemporal (FTD / Pick) |
Hungarian specific (Gajdos): Because of the high cardiovascular/cerebrovascular disease burden, vascular dementia is ~20% more common than Alzheimer's in Hungary — the reverse of the typical Western pattern. Expect this on the oral.
Gajdos classification axes (be ready to name these):
- Course: acute – subacute – chronic
- Anatomy: cortical (AD, Pick) vs subcortical (Binswanger, Parkinson, Huntington) vs mixed (Lewy body)
- Dominant disturbance: mainly cognitive – mainly affective – mainly conative – mixed
- Evolution: progressive – processive (phases/exacerbations) – residual
- Treatability: reversible/treatable vs irreversible ← the axis the exam loves (see 4.100, 5.48)
Etiology mnemonic (Gajdos) — "DEMENTIA": Drug · Emotional · Metabolic · Elderly · Neurologic · Traumatologic · Iatrogenic · Alcohol.
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