About Dementia

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About Dementia

What is Dementia?

Dementia is not a single disease but a general term used to describe a number of symptoms of cognitive decline resulting from brain disorders. It causes a progressive decline in one’s ability to remember, think, reason and communicate. Along with it mood, behaviour and personality too can gradually change. This happens when parts of the brain used for learning, decision making and language are damaged or diseased. Although each person will experience dementia in their own way, at least two of the following core brain functions must be significantly affected to be considered dementia:

  • Memory
  • Communication and language
  • Ability to focus and pay attention
  • Reasoning and judgment
  • Ability to interpret the surroundings

The specific symptoms a person with dementia experiences depends on the parts of the brain damaged and the disease that is causing Dementia

Dementia is not a normal part of ageing. But your risk of developing dementia increases with age. Dementia can be seen in about 5% of over 65 age group and it becomes as high as 20% in the over 80 group.

Other risk factors include:

  1. Smoking
  2. Excessive alcohol intake
  3. Unhealthy diet
  4. Hearing loss
  5. Social isolation
  6. Mental inactivity
  7. Obesity
  8. Diabetes
  9. High blood pressure
  10. High cholesterol
  11. Depression
  12. Physical inactivity

(source : WHO guideline “Risk reduction of cognitive decline and dementia” )


What are the types of Dementia?

The common causes of dementia are Alzheimer’s disease, vascular dementia, Lewy body dementia, Fronto-temporal dementia. Although the cause of disease is different, memory loss is common to all.

Among the less common causes of dementia, some treatable causes can be found. Hypothyroidism, vitamin and other nutritional deficiencies, alcohol and other toxins, brain infections and repeated head trauma are less common causes.

What is Early-onset Dementia?

Dementia occurring in those under 65 years of age, is considered early onset dementia. Many people with early onset are in their 40s and 50s . A higher proportion of cases are due to genetic diseases and the disease tends to worsen rapidly than late-onset cases. However Alzheimer’s disease is the commonest form of dementia in both early-onset and late-onset groups.

Alzheimer’s Disease

  • The most common form of dementia in older adults accounting for 60 to 80 percent of cases and mostly found among females.
  • In cases with onset before the age of 65-70, there is a likelihood of a family history of a similar dementia and a more rapid course.
  • Patients with Down’s syndrome are at high risk of developing Alzheimer’s disease.
  • Alzheimer’s Dementia is at present irreversible.
  • Gradual loss of short term memory loss is one of the earliest signs of Alzheimer’s Disease. For instance forgetting why you went to a shop or that your relatives visited you yesterday
  • Alzheimer’s disease develops slowly but steadily over a period of years and one may live from 3-20 years with the condition.

Vascular Dementia

  • This is the second commonest type and predominantly found among males.
  • Brain damage resulting from a reduced flow of blood to the brain such as from a stroke/ a series of minor strokes can cause vascular dementia. Vascular dementia can be caused by other conditions that reduce the blood supply to the brain too.
  • Many people with vascular dementia may also have Alzheimer’s disease.

Lewy Body Dementia

  • Lewy Body dementia is a type of progressive dementia that leads to impairment of memory, thinking and motor coordination (movement) resulting from protein deposits called Lewy bodies getting deposited in nerve cells causing damage to brain cells over time.
  • Lewy body dementia is considered the third most common cause of dementia accounting for 10–15 per cent of dementia cases.
  • Some Features of Parkinson’s disease like slowing of movements, stiff limbs, difficulty in walking can be present
  • It rapidly worsens than Alzheimer’s disease and average life-span after the onset of symptoms is about seven years.

Frontotemporal Dementia

  • Frontotemporal dementia is caused by progressive nerve cell loss in the brain’s frontal lobes (the areas behind your forehead) or its temporal lobe (the region behind your ears).
  • Most are diagnosed in their 40s and early 60s and is a significant cause of dementia in younger people.
  • There are behavioral changes including early loss of personal and social awareness and language difficulties.
  • Additionally there can be problems in walking and urination.
  • General life expectancy is two to fifteen years.

Alcohol related Dementia

  • Heavy drinking can lead to Korsakoff’s syndrome – a brain disorder which affects short term memory
  • In addition to memory loss, they can have difficulty in learning new skills and acquiring information, changes in personality.
  • If a person abstains from alcohol, adopts a healthy diet and take vitamin supplements, the progress of this disease can be completely halted.


Sources : Shorter Oxford text book of Psychiatry
SL Association of Geriatric Medicine – Dementia holistic approach
ICD 10
ADI international
WHO guideline “Risk reduction of cognitive decline and dementia
LAF newsletters


Dementia Book by Sri Lanka Association of Geriatric Medicine  

ADI Brain Tour