A 72-year-old woman with a 5-year history of insidious memory loss, word-finding difficulty, and progressive functional decline is brought by her son to the psychiatry outpatient clinic. She is oriented to person and place but not to date. She is calm, cooperative, and denies hallucinations or mood symptoms. Cognitive testing shows MMSE 18/30. Her son asks what investigations are needed to confirm the diagnosis and guide treatment. What is the most appropriate next step?

Question

Accepted Answer

B. Perform MRI brain to assess for structural causes and degree of atrophy, and order basic metabolic panel and vitamin B12/folate levels to exclude reversible causes. ## Clinical Presentation

This patient presents with **chronic, progressive dementia** (5-year insidious onset, MMSE 18/30, functional decline). Key features:
- **Insidious onset** over years (not acute)
- **Stable, progressive course** (no fluctuation)
- **Memory and language deficits** → consistent with Alzheimer disease (AD)
- **No hallucinations, agitation, or delirium** → rules out acute delirium
- **Oriented to person and place** → dementia, not delirium

## Diagnostic Workup for Dementia

**High-Yield:** The workup for dementia has two goals:

1. **Rule out reversible causes** (metabolic, nutritional, structural)
2. **Assess severity and structural changes** to guide prognosis and treatment

### Investigations in Dementia

| Investigation | Purpose | Findings in AD |
|---|---|---|
| **MRI brain** | Assess atrophy, rule out stroke/tumor/hydrocephalus | Medial temporal lobe atrophy, hippocampal shrinkage |
| **Basic metabolic panel** | Rule out electrolyte abnormalities, renal/hepatic dysfunction | Usually normal in primary dementia |
| **Vitamin B12 & folate** | Rule out B12 deficiency (reversible dementia) | Normal in AD |
| **TSH** | Rule out hypothyroidism (reversible dementia) | Normal in AD |
| **FDG-PET or amyloid PET** | Confirm AD pathology (research/specialist use) | Hypometabolism in temporal-parietal regions |
| **CSF biomarkers (phospho-tau, amyloid-β)** | Confirm AD pathology (specialist use) | Abnormal in AD |
| **EEG** | Assess for seizures or delirium | Normal in uncomplicated AD |

**Key Point:** For a patient with **suspected Alzheimer disease in primary care**, the standard workup is:
- **Structural imaging (MRI)** to rule out stroke, tumor, normal-pressure hydrocephalus
- **Labs** (metabolic panel, B12, folate, TSH) to exclude reversible causes
- **Cognitive testing** (MMSE, Montreal Cognitive Assessment) to document baseline

**Clinical Pearl:** Advanced imaging (PET, CSF biomarkers) and EEG are reserved for:
- Atypical presentations (young age, rapid progression, focal deficits)
- Diagnostic uncertainty
- Research settings

## Why This Approach?

The patient has a typical presentation of Alzheimer disease. The next step is to:
1. Confirm no structural lesion or reversible cause with MRI and labs
2. Document baseline cognitive function
3. Initiate symptomatic treatment (cholinesterase inhibitor or memantine) once reversible causes are excluded

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## Mnemonic for Reversible Causes of Dementia

**VITAMINS** = **V**itamin B12 deficiency, **I**nfection (neurosyphilis, HIV), **T**hyroid (hypothyroidism), **A**lcohol (Wernicke-Korsakoff), **M**etabolic (electrolytes, renal, hepatic), **I**ntracranial (tumor, hydrocephalus, subdural hematoma), **N**ormal-pressure hydrocephalus, **S**ubstance use

Answer

A. Start memantine 5 mg daily and arrange follow-up in 3 months to assess response

Answer

C. Admit for 24-hour EEG monitoring and neuroimaging to rule out seizures

Answer

D. Refer urgently to neurology for CSF analysis and PET imaging to confirm Alzheimer disease

Explanation

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