Cognitive Disorders

Delirium

Features

•    Acute onset, hours to days

•    Fluctuating course

•    Inattention is hallmark

•    Altered consciousness, disorganised thinking, perceptual disturbances (e.g., hallucinations)

Causes — PINCH ME mnemonic

•    Pain

•    Infection (e.g., UTI, pneumonia)

•    Nutrition (e.g., hypoglycaemia, vitamin deficiencies)

•    Constipation

•    Hydration (dehydration, electrolyte disturbances)

•    Medications (e.g., anticholinergics, benzodiazepines, opioids)

•    Environment (sensory deprivation, unfamiliar surroundings)

Assessment — Confusion Assessment Method (CAM)

1.    Acute onset and fluctuating course (required)

2.    Inattention (required)

3.    Disorganised thinking OR

4.    Altered level of consciousness

•    Diagnosis: features 1 + 2 + either 3 or 4

Management

•    Identify and treat underlying cause (e.g., sepsis, metabolic derangement)

•    Reorientation strategies: clocks, calendars, familiar staff/family

•    Avoid physical restraints

•    Avoid benzodiazepines (except in alcohol withdrawal or severe agitation posing immediate risk)

•    Consider low-dose haloperidol (avoid in Parkinsonism)

Dementia

General features

•    Gradual, progressive decline in memory and other cognitive domains

•    Attention and consciousness usually preserved until late stages

Alzheimer’s disease

•    Most common form (~60%)

•    Early: episodic memory impairment, word-finding difficulties

•    Later: visuospatial deficits, executive dysfunction

•    MRI: medial temporal lobe atrophy (hippocampus), parietal atrophy

•    Associated: apolipoprotein E ε4 allele

Vascular dementia

•    Stepwise deterioration, often after strokes

•    Focal neurological signs (e.g., weakness, gait disturbance)

•    Risk factors: hypertension, diabetes, smoking

•    Imaging: extensive white matter changes (leukoaraiosis), infarcts

Dementia with Lewy bodies (DLB)

•    Fluctuating cognition

•    Prominent visual hallucinations

•    Parkinsonism (rigidity, bradykinesia)

•    REM sleep behaviour disorder (acting out dreams)

•    Neuroleptic sensitivity (avoid typical antipsychotics — severe extrapyramidal symptoms)

Frontotemporal dementia (FTD)

•    Earlier onset (50s–60s)

•    Personality and behavioural changes (disinhibition, apathy, compulsive behaviour, hyperorality)

•    Semantic variant: language impairment

•    MRI: frontal and/or anterior temporal atrophy

Behavioural and Psychological Symptoms of Dementia (BPSD)

•    Includes: agitation, aggression, wandering, hallucinations, delusions

•    First-line management:

o    Non-pharmacological: reassurance, environmental adjustments, music or pet therapy, structured activities

•    Pharmacological:

o    Antipsychotics (e.g., risperidone) only if severe distress or risk

o    Caution: increased risk of stroke and mortality in elderly dementia patients

o    Avoid typical antipsychotics in Lewy body dementia

Extra Revision Pearls

•    Delirium superimposed on dementia: common; high mortality and functional decline

•    Reversible dementias (mimics):

o    B12 deficiency

o    Hypothyroidism

o    Normal pressure hydrocephalus (triad: gait disturbance, dementia, urinary incontinence)

o    Depression ("pseudo-dementia")

•    Acetylcholinesterase inhibitors (e.g., donepezil, rivastigmine):

o    Benefit in mild-moderate Alzheimer’s and DLB

o    Not effective in FTD