Introduction | Symptoms of dementia | Alzheimer's disease | Other major causes of dementia | Diagnosis | Treatment of dementia | Caring for people with dementia

Introduction

Dementia describes a loss of mental function, usually associated with old age, involving problems with memory and reasoning. Dementia is a loss of mental abilities so severe it interferes with a person's ability to function normally at work or in social settings. It is characterized by impairment of short- and long-term memory, and disintegration of personality due to impaired insight and judgment. Dementia is a major public health problem, with a severe impact on millions of affected people and their families.

The symptoms of dementia are not the result of old age. Severe memory loss is never a normal part of growing older. Rather, the symptoms are due to brain diseases, which seem to be more common in older people. Dementia symptoms may be static or progressive depending on the underlying disease, and how it is treated. Static dementia usually follows a single major injury like a severe head trauma or heart attack. It does not progress in severity, but remains stable. Progressive dementia, however, does become worse over time. This type of dementia is found in several major brain disorders.

Whether it occurs suddenly or gradually, dementia causes many disabling symptoms, including:

• memory disturbance

• personality change

• impairment of judgment and control of impulses

• confusion or disorientation

• depression, paranoia or anxiety

• diminishing initiative

• deterioration of intellectual capacity

• obsessive behavior or paranoia

• delusions or psychotic episodes.

The key feature is the decline in intellectual functioning, which significantly interferes with normal social relationships and daily activities.

There are many conditions that may contribute to the development of memory problems and dementia, but Alzheimer's disease and vascular (multi-infarct) dementia cause the vast majority of dementias in the elderly. In vascular dementia, symptoms are caused by long-term reductions in the supply of blood to the brain. Alzheimer's disease and multi-infarct dementia sometimes occur together. Other possible causes of dementia-like symptoms include infections, drug interactions, metabolic or nutritional disorders, brain tumors, depression, or another progressive diseases like Huntington's disease and Parkinson's disease. Dementia is also a symptom seen in AIDS patients in the more advanced stages of illness.

It is clear that the main risk factor for dementia is age. About 3% of men and women between the ages of 65 and 74 suffer from dementia, but after age 65, the percentage of people with dementia approximately doubles with every decade of life. The proportion of people aged 85 and older with dementia is between 25 and 35%. However, it is important to understand that dementia is a disease which is seen more in older people, and is not a normal part of ageing. It is also clear that, as the population of older people grows throughout the world, the number of people with dementia will rise. If current population trends continue, the number of people with dementia could double every 20 years. Currently the causes of dementia are not known for certain, and there is no known cure.

Most often, spouses or other family members provide the day-to-day care for people with dementia. As the disease gets worse, people tend to need more and more care. This can be very demanding for caregivers, and can affect their physical and mental health, family life, jobs, and finances. Caring for a patient with dementia is also very expensive, whether the person lives at home or in a nursing home. The economic impact of dementia is large, and rapidly becoming larger. This is due to both the direct cost of nursing care, as well as indirect costs, such as lost income on the part of patients and their family caregivers.

The biological basis of dementia

The brain contains hundreds of billions of nerve cells (neurons), any one of which can have thousands or hundreds of thousands of connections with other neurons. Within and between these cells travel dozens of chemical messengers - neurotransmitters, hormones and growth factors, which allow each neuron to exchange information with its neighbors in a vast communications network. Somewhere in this complex system lies the cause of dementia. Dementia is thought to disrupt thinking and memory by affecting the transfer of information between neurons.