🎯 Pathology

• also known as Major Neurocognitive Disorder (NMD)

• overall decline in cognitive abilities, memory and communication skills sufficient to hold an individual back from engaging in normal activities of daily living

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💡 Causes

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Common causes

• Alzheimer’s disease (accounts for more than 70% of cases)

• vascular dementia (second most common type of dementia)

• Lewy body dementia

• Parkinson’s disease

 

Rarer causes

• HIV

• frontotemporal dementia (Pick’s disease)

• Cruetzfield Jacob disease (CJD)

 

Reversible causes (must be ruled out)

• hypothyroidism

• B12, folate, thiamine deficiency

• syphillis

• normal pressure hydrocephalus (NPH)

• brain tumour

• chronic subdural haematoma

• depression

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🕵️‍♂️ Assessment

• full patient history

• cognitive assessment tools such as:

  • Mini-mental status examination (MMSE)

  • Montreal Cognitive Assessment (MoCA)

  • 10-point cognitive screener (10-CS)

  • 6-Item cognitive impairment test (6CIT)

• bloods

  • FBC, U&E, TFTs, LFTs, CRP, ESR, blood glucose, vitamin B12 and folate

  • serological tests for syphilis and HIV

• neuroimaging

  • CT/MRI

    • to rule out NPH, chronic subdural haematoma and vascular dementia

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🧩 Differential diagnosis of forgetfulness

 

Alzheimer’s disease

• most common form of dementia

• global progressive cognitive decline

• initially presents with anterograde amnesia, followed by difficulties with engaging in activities of daily living, language deficits

• agitation and depression may also occur

• risk factors: female, Caucasian ethnicity, Down’s syndrome

 

Lewy body dementia

• “fluctuating confusion + features of parkinsonism + visual hallucinations”

• cognitive decline occurs before parkinsonism (at least a year before)

 

Parkinson’s disease

• cardinal features: resting tremor, muscle rigidity and bradykinesia

• cognitive decline may occur in the late stages of the condition

 

Vascular dementia

• “cognitive decline + cardiovascular risk factors”

• cardiovascular risk factors: smoking, hypertension, atrial fibrillation, diabetes mellitus, evidence of previous stroke or transient ischaemic attack

 

Frontotemporal dementia

• “< 65 years + preserved speech + personality changes (such as aggression)”

• associated with degeneration of the frontal and temporal lobes

• the behaviour variant is the most common type

 

Normal pressure hydrocephalus

• reversible

• remember the triad: “wet (urinary incontinence), wobbly (ataxia), wacky (dementia)”

 

Vitamin B12 deficiency

• results in subacute degeneration of the spinal cord which affects the:

  • lateral corticospinal tracts —> upper motor neuron signs (hyperreflexia, Babinski sign, motor weakness, increased muscle tone and spasticity)

  • dorsal columns —> peripheral sensory neuropathy (impaired discriminative touch and proprioception)

  • spinocerebellar tracts —> sensory ataxia (positive Romberg’s sign)

 

Creutzfield Jakob disease

• “rapidly progressive dementia + young patient + myoclonus”

 

Delirium

• “elderly + acute fluctuating confusion/hallucinations/delusions + infection”

• common in the elderly and most commonly precipitated by infections such as urinary tract infections

 

Depression

• short history and acute

• “difficulty with concentration + sleep disturbances + global memory loss”

• worried about test results

 

Hypoglycaemia

• neuroglycopenic symptoms occur when blood glucose levels are < 2.8 mmol/l

• symptoms: confusion, blurred vision, weakness

• may lead to seizures and coma if left untreated

 

Normal ageing process

• cognitive decline is common in the elderly, and it doesn’t mean they have dementia

 

🧲 High-yield tips

• Lewy body dementia vs Parkinson’s disease

  • Lewy body dementia

    • features of parkinsonism occur within < 1 year of cognitive decline, or

    • features of parkinsonism occur following cognitive decline

  • Parkinson’s disease: cognitive decline occurs after ≥ 1 year of parkinsonism

• a mini-mental state examination (MMSE) score of ≤ 24 out of 30 is suggestive of dementia