Understanding Dementia

Definition and Classification

Dementia is not a single disease, but a collective term for various conditions that affect memory, thinking, and behaviour. It is best described as a syndrome — a group of related symptoms that result from damage to the brain.

• Dementia is different from normal ageing — it involves significant decline in cognitive ability
• It includes conditions like Alzheimer’s disease, vascular dementia, Lewy body dementia, and frontotemporal dementia
• It is a global health concern, with increasing prevalence due to ageing populations

How Dementia Affects the Brain

Dementia is caused by progressive damage to brain cells that interferes with their ability to communicate. This damage can stem from a variety of biological processes.

• Brain changes often include shrinkage and loss of connections between nerve cells
• Neurotransmitter imbalances affect memory and mood regulation
• Inflammation and cell damage contribute to cognitive decline

Brain Cell Deterioration

• Neuronal loss: widespread death of brain cells in different areas of the brain
• Disruption in how the brain send signals, breakdown in communication between brain cells is known as synaptic dysfunction.
• ‘Helper cells’ or Glial cell changes: supportive cells that become dysfunctional
• Blood-brain barrier weakening: allows harmful substances to affect the brain

Major Types of Dementia

Alzheimer’s Disease

Alzheimer’s is the most common form of dementia, accounting for 60-70% of cases.

• Caused by build-up of amyloid plaques and tau tangles in the brain
• Primarily affects the hippocampus — the memory centre of the brain which shrinks
• Early signs include memory loss and confusion
• Biomarkers like brain scans and spinal fluid tests aid diagnosis

Vascular Dementia

Vascular dementia is linked to reduced blood flow to the brain, often following strokes or mini-strokes.

• Progression can be sudden (after a stroke) or gradual
• Symptoms include confusion, trouble concentrating, and physical weakness
• Often occurs alongside Alzheimer’s (mixed dementia)
• Prevention involves managing blood pressure, cholesterol, and diabetes

Lewy Body Dementia

Lewy body dementia is caused by abnormal deposits of a protein called alpha-synuclein in the brain.

• Symptoms fluctuate and may include confusion, hallucinations, and movement difficulties
• Can cause vivid visual hallucinations and misperceptions
• Individuals may be very sensitive to certain medications
• Parkinson’s-like motor symptoms are common

Frontotemporal Dementia

Frontotemporal dementia typically affects younger people (often under 65) and targets the front and side parts of the brain.

• Affects behaviour, personality, and language
• May involve apathy, impulsivity, or difficulty with speech and understanding
• Often runs in families and has genetic links
• Brain scans show distinctive patterns of shrinkage

Other Types of Dementia

Less common types of dementia still have significant impact.

• Creutzfeldt-Jakob disease: caused by abnormal prion proteins, progresses rapidly
• Huntington’s disease-related dementia: genetic and affects movement and cognition
• HIV-associated neurocognitive disorder: related to advanced HIV infection
• Alcohol-related dementia: caused by prolonged alcohol misuse

Symptoms and their Progression

Cognitive Symptoms

Memory loss is the hallmark of dementia, but other thinking skills are also affected.

• Problems with attention, decision-making, and planning
• Language difficulties — word-finding, following conversations
• Trouble recognising people, objects, or navigating familiar spaces

Memory Loss Characteristics

• Episodic memory (recent events) is affected early
• Semantic memory (facts) declines more slowly
• Procedural memory (skills) may remain intact until later stages
• Working memory (short-term thinking space) deteriorates

Behavioural and Psychological Symptoms

These symptoms can be distressing for both the person and their carer.

• Mood swings, depression, and anxiety
• Changes in personality, including suspicion or withdrawal
• Delusions or hallucinations, particularly in Lewy body dementia
• Night-time restlessness or reversal of sleep patterns

Functional Decline

As dementia progresses, it affects everyday living.

• Challenges with dressing, eating, toileting, and bathing
• Use of recognised stages of dementia  can help track decline and guide care
• Support strategies focus on safety and preserving independence

Disease Trajectory

Dementia unfolds over years, though the pace varies widely.

• Some types progress steadily; others in sudden steps
• In the later stages, individuals may become non-verbal and bed-bound
• Life expectancy depends on the type of dementia and co-existing conditions

Risk Factors and Prevention

Non-Modifiable Risk Factors

Some risk factors can’t be changed, but they help us understand who may be more vulnerable.

• Age is the strongest known risk factor
• Genetics plays a role, especially in early-onset dementia
• Biological sex may influence risk in certain types
• Poor brain development or early-life disadvantage can have long-term effects

Genetic Considerations

• ApoE4 gene increases risk of Alzheimer’s
• Rare gene mutations cause familial Alzheimer’s and Huntington’s
• Polygenic risk scores are being researched for future use
• Epigenetics explores how environment influences gene function

Modifiable Risk Factors

Taking care of your brain health throughout life can reduce dementia risk.

• Control blood pressure, cholesterol, and heart health
• Keep mentally and socially active
• Eat a balanced diet (e.g. Mediterranean diet), exercise regularly
• Avoid head injuries, smoking, and excessive alcohol

Preventive Approaches

There is no guaranteed way to prevent dementia, but certain strategies are promising.

• Staying mentally stimulated with puzzles, reading, learning
• Staying socially engaged and physically active
• Prioritising good sleep and stress management
• Ongoing research into diet, medication, and brain training