Dementia: Overview & Types - Mind Maze Intro
- Dementia: Acquired, persistent, global impairment of intellect, memory, and personality, without impaired consciousness.
- Mild Cognitive Impairment (MCI): Cognitive decline greater than expected for age/education; daily activities largely preserved.
- Major Domains Affected: Memory, language, attention, executive function, visuospatial skills.
- Types: Alzheimer's (most common), Vascular, Lewy Body, Frontotemporal.
⭐ Dementia is a clinical syndrome, not a specific disease. Alzheimer's Disease is the leading cause.
Alzheimer's Disease - Plaque & Tangle Trouble
- Pathophysiology: Extracellular amyloid-β (Aβ) plaques & intracellular neurofibrillary tau tangles cause neuronal death.
- Genetics: APP, PSEN1, PSEN2 (early-onset, autosomal dominant); APOE ε4 (late-onset risk).
- Clinical: Insidious onset. Progressive memory loss (early, anterograde), language (anomia), visuospatial issues.
- Diagnosis:
- Clinical; MMSE/MoCA (e.g., MMSE < 24/30).
- CSF: ↓Aβ42, ↑Tau, ↑pTau.
- Imaging (MRI): Medial temporal lobe (hippocampal) atrophy. PET for Aβ/tau.
- Management:
- Cholinesterase inhibitors (Donepezil, Rivastigmine, Galantamine) for mild-moderate.
- Memantine (NMDA antagonist) for moderate-severe.
- Supportive care.
⭐ Early-onset AD (< 65 yrs) is often linked to autosomal dominant mutations in APP, PSEN1, PSEN2.
Vascular Dementia - Brain Blood Block
Caused by cerebrovascular disease (multi-infarct, small vessel disease).
- Clinical Features:
- Stepwise or progressive cognitive decline.
- Focal neurological signs (e.g., weakness, reflex asymmetry).
- Prominent executive dysfunction.
- Risk Factors: Hypertension (HTN), Diabetes Mellitus (DM), Hyperlipidemia (HLD), smoking, stroke history.
- Diagnosis:
- Clinical assessment.
- Hachinski Ischemic Score (> 7 suggests VaD).
- Neuroimaging: infarcts, white matter lesions.
⭐ Stepwise deterioration with focal neurological deficits is characteristic of multi-infarct dementia (a type of Vascular Dementia).
Key Other Dementias - Rogue Gallery
| Feature | Lewy Body Dementia (LBD) | Frontotemporal Dementia (FTD) | Parkinson's Disease Dementia (PDD) |
|---|---|---|---|
| Cognition | Fluctuating | Early behavioral/language changes | Late cognitive decline |
| Motor | Parkinsonism (within 1 yr of cognitive decline) | Often absent initially | Parkinsonism precedes dementia by >1 year |
| Hallucinations | Visual (well-formed, recurrent) | Rare | Less common than LBD |
| Key Pathology | Lewy bodies (α-synuclein) | Tauopathy (e.g., Pick bodies) or TDP-43 | Lewy bodies (α-synuclein) |
| Other | REM sleep behavior disorder, neuroleptic sensitivity | Behavioral (disinhibition, apathy) or language (PPA) variants | |
| 📌 Mnemonic | LBD: 'Fluctuating Parkinson's Hallucinations' |
Delirium vs Dementia - Acute vs Chronic Chaos
Key Differentiating Features:
| Feature | Delirium | Dementia |
|---|---|---|
| Onset | Acute (hours-days) | Insidious (months-years) |
| Course | Fluctuating | Progressive |
| Duration | Days-weeks | Months-years |
| Attention | Impaired, fluctuates | Often normal initially |
| Consciousness | Clouded | Clear (until late stages) |
| Hallucinations | Often visual/tactile | Less common early |
| Psychomotor Activity | ↑ or ↓, or mixed | Often normal early |
| Reversibility | Often reversible | Rarely reversible (progressive) |
⭐ Acute onset and fluctuating course with impaired attention are cardinal features of delirium.
High‑Yield Points - ⚡ Biggest Takeaways
- Alzheimer's Disease: Most common dementia; amyloid-beta plaques and hyperphosphorylated tau tangles are key pathologies.
- Vascular Dementia: Second most common; stepwise cognitive decline linked to cerebrovascular events and risk factors.
- Lewy Body Dementia: Characterized by visual hallucinations, parkinsonism, and fluctuating cognition; alpha-synuclein pathology.
- Frontotemporal Dementia: Presents with early personality changes, behavioral disinhibition, or progressive language dysfunction.
- Normal Pressure Hydrocephalus (NPH): Classic triad of dementia, gait disturbance, and urinary incontinence; potentially reversible.
- Creutzfeldt-Jakob Disease (CJD): Rare, rapidly progressive dementia with myoclonus and characteristic EEG/MRI findings.
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