Behavioural disturbance and capacity in probable dementia

The likely diagnosis is probable Alzheimer's disease with behavioural and psychological symptoms, but the differential must be actively considered. The gradual 2-year decline in memory, repetition, getting lost, visuospatial errors and poor recall fit Alzheimer's. The accusations may be delusional misidentification or concealment by family rather than true theft.

Differential:

• Vascular dementia: white-matter changes are modest, and there is no clear stepwise history or focal neurological signs; still possible as a mixed picture.
• Depression-related cognitive impairment: GDS 8/15 is suggestive, but the progressive memory loss and visuospatial deficits are not fully explained by depression.
• Delirium: the recent aggression could reflect infection, pain, constipation, medication effects or sleep disturbance. Check for acute fluctuation.
• Medication effects: oxybutynin is anticholinergic and can worsen cognition and confusion.
• Normal-pressure hydrocephalus, subdural haematoma, thyroid disease, B12 deficiency, syphilis, HIV, alcohol-related brain damage, Lewy body disease, frontotemporal dementia.

Investigations: repeat MMSE or MoCA, collateral functional history, full blood count, renal and liver function, calcium, glucose, TSH, B12, folate, syphilis serology if indicated, urinalysis, ECG, and review of all medications. MRI is already available; consider formal neuropsychological testing. A delirium screen is essential before attributing the aggression to dementia alone. The diagnosis should be explained as a clinical syndrome, with Alzheimer's as the most likely cause, not as a certainty based on one scan.

First, look for reversible triggers: pain, constipation, urinary retention, infection, poor sleep, hunger, overstimulation, and drug effects. Stop or reduce oxybutynin if clinically possible, because anticholinergic burden can worsen cognition and behaviour. Assess whether the caregiver's approach, the environment or fear is driving the aggression. Use the ABC approach - antecedent, behaviour, consequence - and involve the daughter and caregiver in a consistent, calm routine.

Non-drug measures are first-line: orientation cues, familiar objects, regular meals and sleep, exercise, music, simple activities, and caregiver respite. Safety planning is needed because he has hit his caregiver.

Medication should be considered only if aggression is severe, persistent and dangerous, or if non-drug measures fail. Options include risperidone at a low dose or quetiapine; both carry a black-box warning of increased mortality in older people with dementia, and both can cause sedation, falls, parkinsonism and metabolic effects. Use the lowest dose for the shortest time, document the target symptom and review regularly. Avoid typical antipsychotics if there is parkinsonism or possible Lewy body disease. Antidepressants such as sertraline may help if depression or anxiety is prominent, but evidence for aggression is limited. Do not use benzodiazepines routinely because of falls and paradoxical agitation. Monitor pulse, blood pressure, ECG if relevant, and renal function.

The key judgement is that medication is a short-term adjunct, not a solution to a distressed person in a poorly supported care environment. The daughter's question about safety should be answered directly: antipsychotics are not risk-free, and the team should weigh the risk of untreated dangerous behaviour against the medication risk.

Capacity is decision-specific. For finances, assess whether he can understand his income, assets and debts; retain the information; use or weigh it - for example, recognise the risk of scams or repeated large withdrawals; and communicate a choice. Executive dysfunction and memory impairment may make him unable to manage complex accounts even if he can handle small purchases. Ask him to explain a recent bank statement or a proposed transaction, and use collateral from the daughter with his permission or under the applicable law. Do not base the decision on MMSE alone.

For driving, assess cognition, vision, hearing, reaction time, visuospatial ability and insight. He gets lost in familiar streets and has visuospatial errors, which are red flags. He should not drive until a proper fitness-to-drive assessment is completed; the team should follow local reporting rules and advise the licensing authority if required. Inform him and the daughter clearly and document the advice.

Practical steps:

• Arrange a family meeting to discuss lasting power of attorney or guardianship as available under local law, before he loses more capacity.
• Set up banking safeguards: limited cash, alerts, a trusted second signatory, and protection from scams.
• Involve a social worker, occupational therapist and caregiver support.
• Reassess capacity periodically, because it can fluctuate with depression, delirium or medication changes.
• Treat the depression and review anticholinergic drugs, since both can worsen cognition.

The judgement is that he may retain capacity for some simple choices but not for complex finances or driving. The response should be proportionate, documented and protective without unnecessarily removing all autonomy.