Neurology

Dementia

A syndrome of acquired cognitive and functional decline whose cause must be established through longitudinal history, collateral information, examination and targeted investigation, with delirium and treatable contributors addressed first.

In a nutshell

Dementia is a progressive cognitive and functional syndrome that requires a collateral history, delirium assessment, reversible-cause screen, validated cognitive instrument and specialist diagnosis. Treatment is subtype-specific symptomatic medication plus cognitive stimulation, function-focused support, carer support and advance-care planning. Antipsychotics are exceptional treatments for severe distress or immediate risk and are particularly hazardous in Lewy body dementia.

Classic presentation

An older person has gradually progressive memory or executive decline that now impairs medication, finances, cooking or navigation, without acute fluctuation or impaired consciousness; collateral history confirms the trajectory.

Key points

Acute fluctuating confusion with impaired attention or consciousness is delirium until assessed, and delirium may be superimposed on dementia.
Use collateral history and function as well as cognitive testing; a score alone does not diagnose or exclude dementia.
Blood and urine tests address reversible contributors, and MRI or CT helps assess subtype and structural causes but cannot diagnose dementia alone.
For mild-to-moderate Alzheimer's disease, offer a specialist-initiated acetylcholinesterase inhibitor; use memantine for moderate disease when AChE inhibitors are unsuitable or for severe disease, and consider add-on treatment in established moderate or severe disease.
For dementia with Lewy bodies, donepezil or rivastigmine are preferred; memantine is an alternative when AChE inhibitors are unsuitable. Do not use cognitive medicines routinely for frontotemporal dementia or vascular dementia without a relevant comorbid pathology.
Treat distress by addressing pain, delirium, infection, constipation, medicines and environment first; use antipsychotics only for severe distress or risk of harm and review at least every six weeks.
Avoid antipsychotics wherever possible in Lewy body or Parkinson's disease dementia because of motor worsening and severe sensitivity reactions; do not use valproate for agitation or aggression.
Plan support, capacity, lasting power of attorney, advance decisions, driving or work issues, nutrition, swallowing, carers and end-of-life care early and revisit them.

First-line investigation

Collateral history and functional assessment, delirium and physical examination, validated brief cognitive testing, blood and urine tests for reversible causes and specialist structural imaging when dementia remains suspected.

Management

Assess delirium and safety

Treat acute or fluctuating confusion as possible delirium, search for pain, infection, dehydration, constipation, retention and medication causes, and assess capacity, falls, safeguarding and carer strain.^1,3,4

Confirm diagnosis and subtype

Use history, collateral, function, validated cognitive testing, physical examination, reversible-cause tests and specialist CT or MRI; refer to a memory or specialist dementia service when dementia remains suspected.^1,3,4

Use subtype-appropriate cognitive medication

Offer specialist-initiated AChE inhibitor treatment for Alzheimer's disease or Lewy body dementia according to NICE, and use memantine for appropriate moderate or severe Alzheimer's disease or when AChE inhibitors are unsuitable.^1,5,6

Promote cognition, function and wellbeing

Offer group cognitive stimulation therapy for mild-to-moderate dementia, consider occupational or cognitive rehabilitation, and tailor activities, communication, exercise, sensory care and physical-health support.^1,2,5

Reserve antipsychotics for exceptional use

Address clinical and environmental causes first; use an antipsychotic only for severe distress or risk of harm, review at least every six weeks, stop without clear benefit and avoid in Lewy body or Parkinson's disease dementia where possible.^1,7,8,6

Plan support and future care

Provide coordinated post-diagnostic support, carer assessment and skills training, capacity and safeguarding review, advance-care planning, legal and driving advice, nutrition and swallowing review and end-of-life planning.^1,9,10

Exam traps

A sudden deterioration is not automatically dementia progression; assess delirium and its medical or medication trigger.
A normal brief cognitive score does not exclude early, frontal, language-predominant or culturally or educationally masked dementia.
Do not offer acetylcholinesterase inhibitors or memantine for frontotemporal dementia, or routinely for vascular dementia without suspected comorbid Alzheimer's, Lewy body or Parkinson's disease dementia.
Antipsychotics in Lewy body dementia can cause severe sensitivity reactions; avoid them where possible and involve specialists if essential.
Antipsychotics require prior cause assessment, shared risk discussion, lowest dose, shortest duration and at least six-weekly review.
Do not use valproate for agitation or aggression in dementia unless there is another indication.

Illustrations

Cognitive networks and dementia subtypesBrain diagram linking medial temporal, frontal, parietal and subcortical networks to memory, behavioural, language, visuospatial and processing-speed patterns, with mixed pathology noted.PassFinals · original

MRI comparison showing patterns of cerebral atrophyComparative MRI images illustrating that structural patterns may support subtype assessment but cannot diagnose dementia alone.Avinash Chandra, George Dervenoulas &amp, Wikimedia Commons · CC-BY-4.0

Dementia versus deliriumComparison diagram of onset, attention, consciousness and course, with a reminder that delirium may be superimposed on dementia.PassFinals · original

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.