Dementia is not a single disease but an umbrella term describing a group of symptoms, progressive decline in memory, thinking, communication, and behaviour, severe enough to interfere with everyday life. It is caused by diseases that damage and destroy brain cells, most commonly Alzheimer's disease, vascular disease, Lewy body pathology, and frontotemporal degeneration.
Dementia is not a normal or inevitable consequence of ageing. It is a disease, or the result of disease, and while it is more common with advancing age, it can affect people in their 40s and 50s. In Singapore, approximately 1 in 10 adults aged 60 and above has dementia. As Singapore's population ages rapidly, the number of people living with dementia is projected to grow from approximately 100,000 today to over 150,000 by 2030.
Normal Ageing vs Dementia: Understanding the Difference
One of the most important, and most searched, questions about dementia is: 'Is what I'm noticing normal ageing, or something I should be concerned about?' The distinction is clinically meaningful, because not all memory lapses indicate dementia, and because dementia should be evaluated and diagnosed rather than dismissed.
Normal ageing: Occasionally forgetting where you put your keys -- but being able to retrace your steps and find them.
Dementia: Losing objects frequently, putting them in unusual places (keys in the fridge), and being unable to retrace your steps to find them.
Normal ageing: Sometimes forgetting a person's name, but remembering it later.
Dementia: Forgetting the names of close family members. Asking the same question multiple times within the same conversation.
Normal ageing: Taking longer than before to learn a new device or technology.
Dementia: Being unable to learn new things at all; becoming unable to operate devices that were previously familiar.
Normal ageing: Missing a monthly payment occasionally.
Dementia: Persistent difficulty managing finances; falling victim to scams; being unable to follow a recipe that was previously familiar.
The key questions are: Is it getting progressively worse? Is it affecting daily functioning in a way it didn't before? Has someone close to the person noticed the changes? If the answer to any of these is yes, seek a formal cognitive assessment.
Mild Cognitive Impairment (MCI): The Stage Before Dementia
Mild cognitive impairment (MCI) is a clinically recognised intermediate stage between the normal cognitive decline of ageing and the more severe decline of dementia. People with MCI have greater memory or thinking difficulties than would be expected for their age and educational level -- noticeable to themselves or those around them, and confirmable on cognitive testing -- but these difficulties have not yet significantly impaired their ability to manage daily life independently.
MCI is an important diagnosis for several reasons:
- It identifies individuals at elevated risk of progression to dementia -- approximately 10-15% per year convert to dementia, compared to 1-2% of the general older adult population
- It creates an opportunity for preventive intervention: aggressive cardiovascular risk factor management, lifestyle modification, and in selected cases, medication trials
- It allows early legal and financial planning while the person has full cognitive capacity to participate meaningfully
- It enables monitoring, a person diagnosed with MCI can be followed clinically for signs of progression, allowing treatment to begin at the earliest possible opportunity
Types of Dementia
Understanding the type of dementia is important because the cause, progression, management, and prognosis differ between types -- and because certain types have specific treatment implications that make accurate diagnosis clinically critical.
Alzheimer's Disease
Alzheimer's disease account for 60-80% of dementia cases and is caused by the buildup of amyloid plaques and tau tangles in the brain. These damage brain cells and gradually affect memory and thinking. The disease often starts in the hippocampus, the area responsible for memory, and slowly spreads to other parts of the brain. Memory loss, especially difficulty remembering new information, is usually the first major symptom. It progresses through mild, moderate, and severe stages and is most common in people over 65.
Vascular Dementia
Vascular dementia occurs when reduced blood flow or strokes damage brain cells. It can happen after a major stroke or develop gradually from multiple small strokes or blood vessel disease. Unlike Alzheimer’s, it often worsens in steps, with periods of stability followed by sudden decline. Risk factors include high blood pressure, diabetes, high cholesterol, smoking, and obesity. Managing these risk factors can help prevent or slow the condition.
Lewy Body Dementia (LBD)
LBD is caused by the buildup of alpha-synuclein protein (Lewy bodies) in the brain, affecting thinking, memory, and movement. Symptoms may include fluctuating alertness, vivid visual hallucinations, acting out dreams during sleep, and Parkinson-like symptoms such as tremor, stiffness, and slow movement. LBD includes dementia with Lewy bodies and Parkinson’s disease dementia. Correct diagnosis is important because some antipsychotic medicines can cause severe reactions in people with LBD.
Warning Signs: The 10 Early Signs of Dementia
The following ten warning signs, published by Alzheimer's Disease International and adapted for clinical practice, should prompt a medical assessment when they are new, progressive, or noticed by people close to the individual:
- Memory loss that disrupts daily life: Particularly forgetting recently learned information, important dates, or events; asking the same questions repeatedly
- Challenges in planning or solving problems: Difficulty following a familiar recipe, managing accounts, or completing tasks that require sequential steps
- Difficulty completing familiar tasks: Problems driving to a familiar location, managing work tasks, or remembering the rules of a familiar game
- Confusion with time or place: Losing track of dates, seasons, or the passage of time; forgetting where they are or how they got there
- Trouble understanding visual images and spatial relationships: Difficulty judging distance, reading, or recognising faces, you may experience problems driving
- New problems with words in speaking or writing: Difficulty following or joining a conversation; stopping mid-sentence; repeating oneself; using incorrect words
- Misplacing things and losing the ability to retrace steps: Putting things in unusual places; accusing others of stealing
- Decreased or poor judgement: Falling victim to scams; neglecting personal grooming; making unusual financial decisions
- Withdrawal from work or social activities: Avoiding hobbies, social interactions, and activities previously enjoyed; social isolation
- Changes in mood and personality: Becoming confused, suspicious, depressed, fearful, or anxious; being easily upset in unfamiliar situations
Risk Factors for Dementia
Non-Modifiable Risk Factors
- Age: The strongest single risk factor; dementia prevalence roughly doubles every 5 years after age 65.
- Genetic Factors: Certain genes can increase the risk of Alzheimer’s disease. The APOE-e4 variant raises the risk but does not guarantee that someone will develop the disease. Rare mutations in APP, PSEN1, and PSEN2 can cause early-onset familial Alzheimer’s disease.
- Family history: Having a first-degree relative with Alzheimer's modestly increases risk, even in the absence of identified gene mutations.
- Down syndrome: People with Down syndrome have an additional copy of the chromosome that produces amyloid precursor protein; most develop Alzheimer's pathology by their 60s.
Modifiable Risk Factors
- Hypertension in midlife (40-65 years): One of the most clearly established modifiable risk factors; high blood pressure damages cerebral small vessels and contributes to vascular dementia
- Hearing loss: Emerging as an important and treatable risk factor; social isolation and reduced auditory stimulation reduce cognitive reserve; hearing aids reduce this risk
- Physical inactivity: Regular aerobic exercise consistently reduces dementia risk across multiple studies; mechanisms include cardiovascular benefit, neurogenesis in the hippocampus, and inflammation reduction
- Diabetes mellitus: Type 2 diabetes doubles the risk of both Alzheimer's and vascular dementia through vascular damage and insulin signalling disruption
- Social isolation and depression: Chronic social isolation and depression are associated with significantly elevated dementia risk
- Smoking: Increases both vascular and Alzheimer's dementia risk through vascular and oxidative stress mechanisms
- Obesity: Midlife obesity increases risk; adipose tissue produces pro-inflammatory cytokines affecting brain health
- Low educational attainment: Fewer years of formal education reduces cognitive reserve; the brain is less able to compensate for damage before symptoms emerge
- Head injury: Traumatic brain injury, particularly with loss of consciousness, is associated with increased risk, particularly chronic traumatic encephalopathy from repeated head impacts
- Excessive alcohol consumption: Heavy drinking damages neurons directly and increases vascular risk
How Dementia is Diagnosed
Dementia diagnosis requires a comprehensive assessment combining clinical history, cognitive testing, physical examination, and investigations. There is no single test that diagnoses dementia -- the diagnosis is clinical, built from multiple pieces of information.
A critical aspect of a good dementia assessment is obtaining information from a close family member or carer who has observed the person's change over time -- the person with dementia may not be aware of, or may minimise, the extent of their difficulties.
- Clinical History and Interview: A detailed account of when symptoms started, how they have progressed, which cognitive domains are affected, and how they are impacting daily life. Both the patient and an informant (family member or close carer) are interviewed. Previous medical history, medication review (many medications impair cognition), alcohol use, depression, and family history are all assessed.
- Cognitive Assessment: These are standard tests used to assess memory, attention, language, and thinking skills. Both MMSE and MoCA are scored out of 30 and help doctors identify cognitive problems, establish a baseline, and track changes over time. More detailed testing may be done when the diagnosis is unclear.
- Blood Tests: Blood tests can help identify treatable causes of memory and thinking problems. They may check blood count, kidney and liver function, thyroid function, vitamin B12 and folate, calcium, and blood glucose. Other tests, such as syphilis testing or genetic testing, may be done when needed.
- MRI Brain Scan: MRI is the preferred brain scan for dementia. It can show patterns of brain shrinkage that may help identify the type of dementia and can also rule out other causes such as brain tumors, bleeding, hydrocephalus, or stroke-related changes.
- FDG-PET and Amyloid-PET Scan: These are specialised brain scans used when the diagnosis is unclear. FDG-PET shows patterns of brain activity that may help identify different types of dementia, while Amyloid-PET detects amyloid plaques linked to Alzheimer’s disease. They are mainly used for early-onset dementia, uncertain cases, and research or clinical trials.
- Neuropsychological Testing: A detailed assessment of memory, thinking, attention, language, and other cognitive skills carried out by a clinical psychologist. It helps identify specific areas of difficulty, distinguish between different types of dementia, and provide a baseline to track changes over time. It is especially useful in early-stage dementia and younger patients.
Dementia Prevention
While dementia cannot be definitively prevented, research is increasingly clear that lifestyle choices and medical management significantly affect the risk. The Lancet Commission on Dementia Prevention estimates that 40% of dementia cases could potentially be prevented or delayed through modification of 12 risk factors. The strongest evidence supports:
- Blood pressure control from midlife: Maintaining blood pressure below 130/80 mmHg from age 40-65 is associated with significantly reduced dementia risk
- Regular aerobic exercise: 150 minutes of moderate-intensity activity weekly; emerging evidence suggests exercise directly promotes neurogenesis (new brain cell formation) in the hippocampus
- Treating and correcting hearing loss: Wearing appropriately prescribed hearing aids reduces cognitive load and social isolation
- Not smoking: Quitting at any age reduces risk; the earlier the better
- Limiting alcohol to no more than 14 units per week
- Maintaining social connections: Active social engagement throughout life reduces dementia risk independently of other factors
- Staying cognitively active: Lifelong learning, mentally stimulating hobbies, and new skill acquisition build cognitive reserve
- Treating depression promptly and effectively
- Maintaining good sleep: Addressing obstructive sleep apnea (which impairs the brain's glymphatic clearance of amyloid) and ensuring adequate sleep duration (7-8 hours)
- Keeping chronic conditions under control
Supporting a Family Member with Dementia
A dementia diagnosis changes not just the life of the person affected but the lives of everyone who loves and cares for them. Families carry an enormous responsibility -- often without sufficient information, support, or respite.
Practical Guidance for Families
- Learn about the condition: Understanding what is happening in the brain helps families respond with patience rather than frustration when familiar symptoms appear
- Focus on abilities, not deficits: Dementia takes abilities, but many abilities remain intact for a long time. Focus on what the person can still do and enjoy.
- Communication strategies: Speak clearly and simply; one sentence or question at a time; avoid arguing about facts the person misremembers; validate the emotion rather than correcting the content
- Establish routine: People with dementia function better in predictable, familiar environments and routines; consistency reduces confusion and agitation
- Safety at home: Assess for hazards; consider door alarms for wandering; review driving safety with the specialist; manage medications carefully
- Plan ahead: While the person with dementia can still participate, discuss and document their wishes for future care; review legal documents (LPA -- Lasting Power of Attorney in Singapore); consider financial planning
