Dementia (Latin: de-‘ apart’;mens-‘mind’) refers to the progressive degeneration in cognitive functions, caused by rapid or gradual alterations in the brain. These changes may be triggered by brain damage or by certain diseases.

Dementia is not the name of a specific disease, but is a term used to refer to a group of symptoms. It commonly affects the older people, although it may manifest at any stage of adulthood.

Cognitive functions involve the ability to think, to perceive, and to learn. Some of the common cognitive functions that are impacted by dementia are:

• Memory
• Thinking
• Attention span
• Reasoning
• Judgment
• Making Decisions
• Problem solving
• Language
• Verbal communications, and
• Spatial orientation

Incidence

The prevalence of dementia has multiplied over the past decades. This could stem from greater awareness, precise diagnosis or better treatment modalities resulting in an expanding population of the elderly.

A recent estimate showed an existing population of 24·3 million dementia-affected persons, with 4·6 million new cases being added every year. This score is likely to double, every 20 years.

The majority of the affected individuals live in developing countries (60% in 2001, expected to rise to 71% by 2040). Rates are expected to increase by more than 300 % in India, China, South Asian and in the Western Pacific countries.

In the United States, an estimated 2 million people are reported to be affected by severe dementia, while 1 to 5 million people are victims of mild to moderate dementia. 5-8% of those above 65 years of age, have some form of dementia; the estimate doubles for every 5 years after 65 years.

Types

Dementia can be broadly classified as reversible and non –reversible dementia. Some types of dementia are partially or totally reversible with treatment. The nature of damage and the speed with which the underlying cause is treated determines whether the disease is reversible or not.

a) Alzheimer’s Disease (AD), the most common cause, is incurable and can be classified under irreversible dementia. It is present in two thirds of the affected people. AD is a progressively degenerating disease, characterized by brain lesions, that gradually kill the neurons responsible for cognition.

b) Vascular Dementia, also called Multi-Infarct Dementia, shares many symptoms with Alzheimer’s disease. It is caused by a defect in the blood supply to the brain. There is no cure for this type of dementia. Symptoms may appear suddenly and they include-

• Getting lost in familiar surroundings
• Memory problems
• Rapid, shuffling steps
• Slurred speech
• Loss of bladder / bowel control
• Unwarranted laughing / crying

c) Mixed dementia, or Alzheimer’s Disease, with Concomitant Cerebrovascular Disease (AD with CVD), is now recognized by many as a specific clinical condition.

Causes of Memory Loss

Dementia results from the destruction of brain cells. The greatest risk factor implicated in dementia is, of course, old age.