Dementia — SAQ

Stem

A candidate is asked to manage a classic presentation of Dementia in an exam setting. Use precise definitions, scores, doses, and decision thresholds.

Core knowledge (model answer backbone)

Dementia is an acquired, persistent, global impairment of higher cortical functions (memory, language, visuospatial skills, executive function, personality) occurring in clear consciousness, sufficient to interfere with activities of daily living. It is not a single disease but a syndrome. The commonest cause is Alzheimer disease (AD) (60 to 70 percent), driven by amyloid-beta 42 plaque deposition and tau-hyperphosphorylated neurofibrillary tangles with a cholinergic deficit; followed by vascular dementia (VaD), dementia with Lewy bodies (DLB) and frontotemporal dementia (FTD). Presentation is progressive and insidious in AD, stepwise in vascular, fluctuating with visual hallucinations and parkinsonism in DLB, and behavioural/personality change in FTD. Always exclude reversible mimics — delirium (acute, fluctuating, clouded consciousness), depression (pseudodementia), normal ageing, and treatable metabolic causes (B12, folate, TSH, syphilis, HIV, NPH). Cognitive screening uses MMSE (under 24) or the more sensitive MoCA (under 26); confirm with structural and (where indicated) functional neuroimaging and CSF/PET biomarkers. Cholinesterase inhibitors (donepezil 5 to 10 mg, rivastigmi

Red flags

• Acute onset or fluctuating course suggests DELIRIUM, not dementia - search for and treat the precipitant
• Rapid progression over weeks to months raises suspicion of CJD, paraneoplastic limbic encephalitis or autoimmune dementia
• Early, prominent behavioural/personality change with relative memory sparing points to frontotemporal dementia
• Fluctuating cognition with detailed visual hallucinations and parkinsonism - dementia with Lewy bodies; NEVER give a typical antipsychotic (neuroleptic sensitivity can be fatal)

High-yield structure examiners expect

Cover: Overview & Definition, Classification, Epidemiology & Risk Factors, Pathophysiology, Clinical Presentation, Differential Diagnosis.

Key doses / thresholds (from topic teaching)

• transdermal patch 4.6 mg per 24 h**, up to **13
• target of 20 mg once daily** (10 mg twice daily); **red
• max 10 mg)**
• donepezil 5 to 10 mg, rivastigmine patch 4
• galantamine ER 16 to 24 mg) for mild-moderate AD and DLB
• lecanemab 10 mg per kg IV 2-weekly, with ARIA MRI monit

Questions

a) Define the condition and give the most important classification or severity framework used in exams. (3 marks)

• Clear one-line definition matching standard teaching.
• Named classification / stages / types with discriminating features.
• One sentence on why classification changes management.

b) Outline pathophysiology in a mechanism chain that explains the main clinical features. (3 marks)

• Initiating insult → intermediate pathway → end-organ effect.
• Link at least two symptoms/signs to mechanism.
• Mention one complication pathway (e.g. shock, perforation, herniation, arrhythmia).

c) List discriminating clinical features and bedside assessment. (3 marks)

• Classic presentation plus one atypical group (elderly, pregnancy, child, immunocompromised).
• Named signs/manoeuvres if relevant.
• What must never be missed on exam/bedside (pregnancy test, airway, glucose, etc.).

d) Investigations with thresholds and one named score if applicable. (3 marks)

• First-line tests and what positive findings mean.
• Gold-standard or definitive investigation when needed.
• Score components reproduced exactly if a named score is standard for this topic.

e) Immediate resuscitation and definitive management with doses where standard. (3 marks)

• ABC / time-critical steps first.
• First-line drug(s) with agent + dose + route (or procedure steps).
• Escalation triggers (theatre, ICU, thrombolysis window, antidote, etc.).
• Disposition and safety-netting.

Marking tips

Full marks require specificity (numbers, names, doses) not generic "give antibiotics/fluids." Regional practice (ICMR / NICE / AHA) may be cited as alternative where relevant.