🧠 Alzheimer’s Disease (AD) = the commonest cause of dementia, affecting ~10% of people >65. Characterised by progressive cognitive decline, memory loss, and behavioural changes. Diagnosis is clinical, supported by cognitive testing, imaging, and history.

ℹ️ About

Diagnosis = patient/family history + cognitive testing + exam + imaging.
⚠️ Progressive decline in cognition & daily function.
Common in older age; prevalence increases markedly >80 yrs.

🧬 Aetiology

Increased prevalence in Down syndrome (chromosome 21 link).
Genetic link to apolipoprotein E4.
Pathophysiology: reduced cholinergic, noradrenergic, dopaminergic activity.

🔬 Pathology

⬇️ Acetylcholine in brain/CSF.
Neurofibrillary tangles: Tau protein inside neurons.
Senile plaques: β-amyloid deposits in hippocampus, basal forebrain, cortex.

🧬 Genetics

Rare autosomal dominant: Presenilin 1, Presenilin 2, APP genes.
ApoE e4 homozygotes at much higher risk.

⚠️ Increased Risks

Age, family history, traumatic brain injury.
Diabetes, hypertension, cardiovascular disease.
Down syndrome.

👩‍⚕️ Clinical Features

📉 Progressive memory loss (esp. episodic memory).
🧭 Disorientation, visuospatial difficulty.
🖐️ Dyspraxia, agnosia, impaired executive planning.
😟 Behavioural: anxiety, irritability, depression, aggression, loss of insight.

🔎 Investigations

🧪 Bloods: FBC, U&E, LFTs, TFTs, B12, folate (exclude reversible causes).
🖥️ Imaging: CT/MRI → hippocampal atrophy (MRI best for progression).
EEG: mild nonspecific slowing.
Histology (post-mortem): tau tangles & β-amyloid plaques.

🧾 Differential Diagnoses

Dementia with Lewy bodies.
Vascular dementia.
Depression (pseudo-dementia).

🎯 Management Goals

Maximise independence & quality of life.
Support cognition, mood, behaviour.
Provide safe environment & social support.

💊 Management

Specialist assessment in memory clinic.
Cognitive enhancers:
- Donepezil 5–10 mg daily
- Galantamine 8–24 mg daily
- Rivastigmine 1.5–6 mg BD or transdermal patch
- Memantine (NMDA antagonist)
Depression: SSRIs.
Agitation: low-dose antipsychotics (quetiapine, risperidone, olanzapine) — only if severe, non-pharmacological methods first.
Social services, MDT support (OT, PT, social work, carers, support groups).

🌅 End-of-Life Care

Focus shifts to palliation, advanced care planning.
Mortality ~10% per year in advanced disease.

💡 Exam Pearl: Think Alzheimer’s when you see: older patient + progressive memory loss + hippocampal atrophy + no stepwise decline (unlike vascular dementia).

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Alzheimer disease (Dementia)