Dementia: Early Signs, Types, Causes, and Prevention

Intro

Dementia is a clinical syndrome characterised by progressive decline in memory, thinking, behaviour, and the ability to carry out daily activities. It is caused by diseases that damage the brain — most commonly Alzheimer’s disease, but also vascular, Lewy body, and frontotemporal conditions.

It is not a normal part of aging. While some cognitive slowing occurs with age, dementia represents disease — and the evidence now shows that for many people, risk can be meaningfully reduced.

Over 55 million people worldwide live with dementia. That number is projected to triple by 2050. Early recognition, accurate diagnosis, and evidence-based prevention matter more than ever.

Key Points

Alzheimer’s disease causes 60–70% of dementia cases; vascular dementia is the second most common type
Dementia symptoms go beyond memory loss — behaviour, judgment, language, and personality are all commonly affected
The Lancet Commission (2024) identifies 14 modifiable risk factors accounting for up to 45% of cases
Blood pressure control is the single highest-yield preventive intervention
Early diagnosis enables planning, access to support, and in some cases, earlier treatment
Dementia is not a normal part of aging — if symptoms are progressing, seek assessment

What Is Dementia?

Dementia is not a single disease. It is a syndrome — a cluster of symptoms caused by different underlying conditions that damage the brain. Common features across all types include:

Memory impairment — particularly difficulty forming new memories or recalling recent events
Language difficulty — word-finding problems, reduced fluency
Executive dysfunction — difficulty planning, organising, or completing complex tasks
Visuospatial problems — difficulty navigating familiar environments or recognising faces
Behavioural and personality change — disinhibition, apathy, agitation, mood disturbance

To be classified as dementia, these symptoms must be significant enough to impair daily functioning and represent a decline from a previous level.

Common Types of Dementia

Alzheimer’s Disease (60–70% of cases)

The most common form. Caused by accumulation of abnormal proteins — amyloid plaques and tau tangles — that damage neurons and disrupt brain networks. Typically begins with short-term memory difficulty, progressing over years to affect all areas of cognition.

See: Alzheimer’s Disease Overview

Vascular Dementia (15–20%)

Caused by reduced blood supply to the brain — through stroke, small vessel disease, or multiple microinfarcts. Risk factors overlap significantly with cardiovascular disease: hypertension, diabetes, atrial fibrillation, and smoking. Cognitive decline may be stepwise rather than gradual.

Lewy Body Dementia (10–15%)

Characterised by the accumulation of alpha-synuclein protein (Lewy bodies) in the brain. Features include fluctuating cognition, vivid visual hallucinations, REM sleep behaviour disorder, and Parkinsonism. Certain medications (including some antipsychotics) can cause serious adverse reactions and must be avoided.

Frontotemporal Dementia (FTD)

Affects the frontal and temporal lobes. Presents most commonly with personality and behavioural change — disinhibition, loss of empathy, compulsive behaviours — rather than memory loss. Often affects younger people (50s–60s). Language variants (primary progressive aphasia) also exist.

Mixed Dementia

Many people — particularly those over 80 — have more than one type of dementia pathology simultaneously, most commonly Alzheimer’s combined with vascular disease.

Early Signs and Symptoms

Dementia often develops gradually. Early signs are frequently missed or attributed to normal aging. Watch for patterns that represent a change from the person’s baseline:

Memory and Thinking

Repeatedly asking the same questions or retelling the same stories
Forgetting recent events while remembering distant memories clearly
Difficulty following conversations, books, or TV programmes
Trouble concentrating or completing familiar tasks

Language and Communication

Struggling to find the right word (beyond occasional normal word-finding lapses)
Losing the thread of conversations
Difficulty understanding spoken or written language

Orientation and Navigation

Getting confused in familiar places
Losing track of dates, days, or seasons
Difficulty judging time or sequence

Everyday Function

Difficulty managing finances, medications, or appointments
Problems with driving (getting lost, misjudging distances)
Withdrawing from social activities and hobbies previously enjoyed

Behaviour and Personality

Increased anxiety, irritability, or suspicion
Apathy or loss of initiative
Socially inappropriate behaviour (more typical of frontotemporal dementia)
Sleep disturbance or confusion at night

Important: Memory loss alone does not define dementia. Changes in behaviour, judgment, and personality are often the earliest — and most distressing — signs, and may precede significant memory problems by years.

Diagnosis and Assessment

Who Should Assess?

A GP can begin assessment and exclude reversible causes. Complex or uncertain cases are typically referred to a specialist — neurologist, geriatrician, or old age psychiatrist — often via a memory clinic.

The Diagnostic Process

History A detailed account from both the person and a family member or close carer is essential. The pattern, rate of progression, and functional impact are key.

Cognitive Assessment Standardised tools — such as the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), or Addenbrooke’s Cognitive Examination (ACE) — provide a structured, reproducible measure of cognitive function across domains. For a full explanation of what these tests involve and what to expect, see Cognitive Testing and Memory Assessment.

Blood Tests To exclude reversible causes: thyroid function, B12 and folate, full blood count, kidney and liver function, blood glucose, inflammatory markers.

Brain Imaging CT or MRI helps identify vascular changes, tumours, hydrocephalus, or atrophy patterns consistent with specific dementia types.

Specialist Biomarker Testing In selected cases, amyloid PET imaging, CSF analysis (amyloid-beta, tau), or emerging blood-based biomarkers (plasma p-tau217) can confirm Alzheimer’s pathology and support treatment eligibility decisions.

Reversible Causes to Exclude

Several conditions can mimic dementia and are treatable:

Depression (including pseudodementia in older adults)
Hypothyroidism
Vitamin B12 or folate deficiency
Normal pressure hydrocephalus
Medication side effects (especially anticholinergic and sedative drugs)
Alcohol-related brain injury
Delirium superimposed on dementia — sudden worsening in someone with known cognitive decline requires urgent assessment

Treatment and Support

Medications

Acetylcholinesterase Inhibitors (donepezil, rivastigmine, galantamine) Used for mild to moderate Alzheimer’s and Lewy body dementia. They modestly improve cognitive and functional symptoms in some patients. Side effects include nausea, diarrhoea, and vivid dreams.

Memantine Used in moderate to severe Alzheimer’s, often in combination with a cholinesterase inhibitor. Acts on glutamate pathways. Generally well tolerated.

Anti-Amyloid Therapies Lecanemab and donanemab — newer monoclonal antibodies that clear amyloid from the brain — have shown meaningful slowing of decline in early Alzheimer’s disease in clinical trials. Access is expanding but remains limited; they carry risks including brain microhaemorrhage (ARIA) and require careful monitoring.

For other dementia types: there are no disease-modifying treatments for vascular, frontotemporal, or Lewy body dementia. Management focuses on modifiable vascular risk factors (for vascular dementia) and symptom management.

Non-Pharmacological Approaches

Strong evidence supports:

Structured activity and engagement — cognitive stimulation, music, reminiscence therapy
Physical activity — benefits cognition and mood
Sleep management — treating insomnia and sleep apnoea reduces burden on the brain
Carer support — carer education, respite, and psychological support reduce breakdown and improve quality of life for both person and carer

Planning and Support

Early diagnosis enables:

Legal and financial planning while capacity is retained (lasting power of attorney)
Advance care planning
Access to local dementia support services and national organisations
Driving assessment if appropriate

Risk Factors and Prevention

The Lancet Commission on Dementia Prevention, Intervention, and Care (2024) updated its list to 14 modifiable risk factors, collectively accounting for up to 45% of dementia cases worldwide.

Risk Factor	Life Stage	Relative Impact
Low education	Early life	Moderate
Hearing loss	Midlife	High
High blood pressure	Midlife	High
Obesity	Midlife	Moderate
Physical inactivity	Midlife–late	Moderate
Diabetes	Midlife–late	Moderate
Smoking	Midlife–late	Moderate
Depression	Midlife–late	Moderate
Social isolation	Late life	Moderate
Excessive alcohol	Midlife–late	Moderate
Traumatic brain injury	Any	Moderate
Air pollution	Late life	Moderate
Untreated vision loss	Late life	Moderate
High LDL cholesterol	Midlife	Moderate

What the Evidence Supports

Control blood pressure — the single highest-yield intervention. Hypertension in midlife significantly increases dementia risk decades later.

Stay physically active — aerobic exercise reduces risk through multiple mechanisms: improving cerebral blood flow, reducing vascular risk factors, and building cognitive reserve.
See: Alzheimer’s Prevention and Exercise

Eat well — Mediterranean-style and MIND diet patterns show consistent associations with slower cognitive decline.
See: MIND Diet

Treat hearing loss — the largest single modifiable risk factor in midlife. Untreated hearing loss reduces cognitive stimulation and social engagement.

Sleep — the brain’s glymphatic system clears metabolic waste (including amyloid) during sleep. Chronic poor sleep is independently associated with dementia risk. Treat sleep disorders, including sleep apnoea.
See: Sleep Health · Sleep Apnoea

Manage metabolic and vascular risk — control diabetes, reduce cardiovascular risk, stop smoking.
See: Cardiovascular Risk Assessment · High Blood Pressure

Stay socially and cognitively engaged — social isolation doubles dementia risk. Learning new complex skills (a language, an instrument) builds cognitive reserve.
See: Social Connection

When to Seek Medical Review

Seek urgent or emergency review if:

Sudden confusion or rapid cognitive decline (may indicate delirium, stroke, or another acute cause)
New severe headache with cognitive change
Sudden changes in personality or behaviour

See your GP promptly if:

Memory or cognitive problems are getting progressively worse
Symptoms are affecting daily activities — work, finances, driving, self-care
Family or carers have raised concerns about memory or personality change
You have a strong family history of dementia and are concerned about your own risk

A reversible cause can always be excluded. Early assessment is valuable — for planning, for access to support, and increasingly for treatment eligibility.

FAQ

Q: Is memory loss a normal part of aging?
A: Some slowing of memory recall is a normal part of aging. Dementia is not. Dementia causes cognitive decline that disrupts daily function. If memory problems are worsening or affecting everyday activities, seek medical assessment.

Q: What is the difference between Alzheimer’s disease and dementia?
A: Dementia is an umbrella term for a group of symptoms — memory loss, confusion, personality change — caused by brain disease. Alzheimer’s disease is the most common specific cause, accounting for 60–70% of cases.

Q: Can dementia be prevented?
A: Not entirely — but up to 45% of cases may be attributable to modifiable risk factors. Controlling blood pressure, staying physically active, treating hearing loss, managing sleep, and avoiding smoking all reduce risk — particularly when addressed in midlife.

Q: What are the very first signs of dementia?
A: Early signs often include: repeatedly asking the same question, forgetting recent conversations, misplacing items in unusual places, difficulty with finances or planning, and subtle personality or mood changes. These are often first noticed by family.

Q: How is dementia diagnosed?
A: Through clinical history (including from family), cognitive assessment, blood tests to exclude reversible causes, and brain imaging when indicated. Specialist biomarker testing is increasingly available for early or more precise diagnosis.

Q: Are there treatments for dementia?
A: There is no cure. For Alzheimer’s disease, cholinesterase inhibitors and memantine can modestly slow symptoms. Newer anti-amyloid therapies (lecanemab, donanemab) have shown benefit in selected early-stage cases. Non-pharmacological approaches are central to quality of life for all types.

Q: When should I see a doctor about memory concerns?
A: See your doctor if symptoms are getting worse over time, affecting daily activities, concerning to family, or accompanied by personality or behavioural change. A reversible cause must always be excluded first.