An 80-year-old with known Alzheimer disease becomes markedly more confused over two days. He is drowsy, inattentive, and worse at night. What is the most likely explanation? A. Normal progression of his dementia B. Delirium from an acute cause C. Development of Lewy body dementia D. Depression ANSWER: B — delirium from an acute cause. Why: the TIME COURSE gives it away. Two days is far too fast for dementia to progress. Add impaired attention, drowsiness and worsening at night and this is delirium. Dementia is the strongest risk factor for delirium, so the two coexist constantly — a known diagnosis of dementia does not explain a sudden change. Look for infection, pain, urinary retention, constipation, dehydration or a newly started drug.

Which feature most reliably distinguishes delirium from dementia at the bedside? A. Memory impairment B. Impaired attention with a fluctuating course C. Disorientation to time D. Presence of hallucinations ANSWER: B — impaired attention with a fluctuating course. Why: memory impairment (A) and disorientation (C) occur in BOTH, so they do not discriminate. Hallucinations (D) occur in delirium and also in Lewy body dementia. Inattention — the patient cannot hold a thread or follow a simple sequence — together with a course that waxes and wanes is the combination that points to delirium.

A 76-year-old with fluctuating confusion, recurrent visual hallucinations and mild parkinsonism becomes agitated on the ward. Why must antipsychotics be avoided or used only on specialist advice? ANSWER: this picture suggests LEWY BODY DEMENTIA, which carries severe antipsychotic sensitivity. Such patients can develop severe rigidity, collapse and marked deterioration that may be IRREVERSIBLE. The danger is that the presentation invites the error: an older, confused, hallucinating patient is exactly the situation in which an antipsychotic is usually considered. WHAT TO DO INSTEAD: look for a cause of the distress — pain, urinary retention, constipation, hunger, fear, unfamiliar surroundings — and seek specialist advice before prescribing.

An older woman is brought in with "memory problems". She answers most questions with "I don't know", appears low in mood, has poor concentration and has lost weight and sleep. What must be considered before diagnosing dementia? ANSWER: DEPRESSION — the great mimic. Depression in older people commonly presents with poor concentration, slowed thinking and apathy, which families report as memory loss. A CLINICAL POINTER: a depressed patient often says "I don't know" and gives up quickly, whereas a patient with dementia frequently confabulates and tries to cover the gap. WHY IT MATTERS: depression is treatable. Missing it means leaving a reversible illness untreated and giving a family a false prognosis.

Match each dementia subtype to its most characteristic feature. ANSWER: ALZHEIMER Gradual onset with early loss of memory for recent events; slow steady decline. VASCULAR STEPWISE deterioration; vascular risk factors; focal neurological signs. LEWY BODY VISUAL HALLUCINATIONS, fluctuating cognition, parkinsonism; antipsychotic sensitivity. FRONTOTEMPORAL Younger onset; PERSONALITY and behaviour change first, with memory relatively spared early. NOTE: mixed pathology is common in the very old, particularly Alzheimer with vascular change. A confident single label is often less honest than acknowledging the mixture.

Does a diagnosis of dementia mean a patient cannot consent to treatment? ANSWER: No. Capacity is DECISION-SPECIFIC and TIME-SPECIFIC. Many people with dementia retain capacity for a great many decisions — where to live, what to eat, whether to accept a particular treatment — long after losing it for complex financial matters. Capacity may also FLUCTUATE: present in the morning and absent in the evening, or lost during a delirium and regained afterwards. LEARNING POINT: assess capacity for the decision actually being made, at the time it is being made. The diagnostic label is not the assessment.