Dementia

Dementia is a chronic, progressive neurocognitive disorder characterized by a decline in one or more cognitive domains sufficient to interfere with independence in everyday functioning. It typically affects memory initially, with gradual progression to impair language (dysphasia), object recognition (agnosia), motor planning (apraxia), executive function, social cognition, and eventually personality and behaviour. Dementia is not a normal consequence of ageing and should be distinguished from delirium and other reversible causes of cognitive impairment.

Epidemiology

Dementia is one of the leading causes of disability and dependency among older adults worldwide. The prevalence increases markedly with advancing age, with Alzheimer's disease being the most common cause, followed by vascular dementia, dementia with Lewy bodies, and frontotemporal dementia.

Risk factors

Non-modifiable risk factors

• Advanced age

• Family history of dementia

• Genetic predisposition

• Down syndrome

Modifiable risk factors

• Hypertension

• Diabetes mellitus

• Dyslipidaemia

• Smoking

• Excessive alcohol consumption

• Obesity

• Physical inactivity

• Depression

• Traumatic brain injury

• Stroke

• Low educational attainment

• Social isolation

Pathophysiology

Dementia results from progressive neuronal dysfunction and loss within multiple areas of the brain. The underlying mechanisms vary according to the specific type of dementia and may include accumulation of abnormal proteins, cerebrovascular disease, neurodegeneration, inflammation, and synaptic dysfunction. Progressive neuronal loss leads to deterioration of memory, cognition, behaviour, and functional abilities.

Clinical presentation

The onset is usually gradual with progressive deterioration over months to years. Memory impairment is often the earliest symptom, followed by impairment in language, executive function, visuospatial abilities, and behaviour.

Symptoms

• Progressive memory loss

• Difficulty learning new information

• Forgetfulness

• Difficulty finding words

• Difficulty understanding language

• Difficulty performing familiar tasks

• Impaired planning and decision-making

• Poor judgment

• Difficulty recognizing people or objects (agnosia)

• Difficulty carrying out learned motor activities (apraxia)

• Personality changes

• Behavioural changes

• Social withdrawal

• Reduced ability to perform activities of daily living

Clinical signs

• Impaired short-term and long-term memory

• Reduced attention and concentration

• Executive dysfunction

• Language impairment (dysphasia)

• Agnosia

• Apraxia

• Impaired visuospatial function

• Disorientation to time and place

• Poor insight

• Behavioural disturbances

• Functional dependence in daily activities

Differential diagnosis

• Delirium

• Mild cognitive impairment

• Major depressive disorder (pseudodementia)

• Normal ageing

• Hypothyroidism

• Vitamin B12 deficiency

• Normal pressure hydrocephalus

• Brain tumour

• Chronic subdural haematoma

• Parkinson disease dementia

• Medication-induced cognitive impairment

Diagnostic criteria

Diagnosis is based on the DSM-5 criteria for Major Neurocognitive Disorder.

The following criteria should be met:

• Significant cognitive decline from a previous level of performance in one or more of the following cognitive domains:

  • Complex attention

  • Executive function

  • Learning and memory

  • Language

  • Perceptual-motor function

  • Social cognition

• The cognitive deficits interfere with independence in everyday activities and require assistance with instrumental or basic activities of daily living.

• The deficits are not better explained by delirium or another mental disorder.

Investigations

Cognitive assessment

• Mini-Mental State Examination (MMSE)

• Functional assessment

• Behavioural assessment

Laboratory investigations

• Full blood picture (FBP)

• Blood glucose

• Serum electrolytes

• Renal function tests

• Liver function tests

• Thyroid function tests

• Vitamin B12 level

• Folate level

• Syphilis or HIV testing where clinically indicated

Imaging

• CT scan of the brain

• MRI of the brain where available or clinically indicated

Management

Management aims to slow cognitive decline, optimize functional independence, manage behavioural symptoms, support caregivers, and treat reversible contributing factors.

Initial management includes:

• Confirm the diagnosis.

• Exclude reversible causes of cognitive impairment.

• Assess functional status and behavioural symptoms.

• Educate the patient and caregivers.

• Develop an individualized long-term care plan.

Non-pharmacological treatment

• Provide psychoeducation to the patient and family regarding the nature and progression of the disorder.

• Perform Mini-Mental State Examination (MMSE), functional assessment, and behavioural assessment every 6 months.

• Encourage regular physical activity.

• Promote cognitive stimulation and structured daily routines.

• Ensure adequate nutrition and hydration.

• Optimize hearing and vision.

• Assess home safety and reduce fall risks.

• Provide caregiver education and psychosocial support.

• Encourage advance care planning where appropriate.

Pharmacological treatment

Mild to moderate dementia

• Donepezil – 5 mg – PO – once daily initially; may increase to 10 mg once daily after 4–6 weeks.

Moderate to severe dementia

• Donepezil – 5 mg – PO – once daily initially; may increase to 10 mg once daily after 4–6 weeks; may be further increased to 23 mg once daily after 3 months.

Management according to underlying cause

Alzheimer's disease

• Initiate Donepezil therapy as indicated.

• Provide ongoing cognitive and functional assessment.

Vascular dementia

• Optimize control of hypertension, diabetes, dyslipidaemia, and other vascular risk factors.

• Implement secondary stroke prevention where indicated.

Behavioural and psychological symptoms

• Identify and manage precipitating factors.

• Use non-pharmacological interventions as first-line treatment.

• Consider pharmacological therapy only when symptoms are severe, persistent, or pose a risk to the patient or others.

Reversible causes of cognitive impairment

• Correct metabolic abnormalities.

• Treat infections.

• Review and discontinue medications contributing to cognitive impairment where appropriate.

Referral

Refer patients to a specialist in psychiatry, neurology, geriatrics, or internal medicine when appropriate.

Urgent referral is indicated for patients with:

• Rapidly progressive cognitive decline.

• Uncertain diagnosis.

• Early-onset dementia (before 65 years of age).

• Severe behavioural disturbance.

• Suspected reversible neurological disorder.

• Significant caregiver burden requiring multidisciplinary support.

Complications

• Progressive functional dependence.

• Malnutrition and dehydration.

• Falls and fractures.

• Wandering.

• Behavioural and psychological symptoms.

• Aspiration pneumonia.

• Pressure ulcers.

• Recurrent infections.

• Caregiver stress and burnout.

• Increased mortality.

Prognosis

Dementia is generally progressive and irreversible, although the rate of progression varies according to the underlying cause. Early diagnosis, appropriate pharmacological therapy, management of comorbidities, and comprehensive caregiver support may improve quality of life and delay functional decline.

Prevention

Preventive strategies include controlling cardiovascular risk factors, maintaining regular physical activity, adopting a healthy diet, avoiding tobacco and excessive alcohol consumption, remaining socially and cognitively active, treating hearing impairment, and managing chronic medical conditions that increase the risk of cognitive decline.