What is dementia?
Dementia is significant loss of intellectual abilities such as memory capacity, severe enough to interfere with social or occupational functioning.
What is not dementia?
Dementia is not temporary confusion or forgetfulness that might result from a self-limited infection, underlying illness, or side effects of medications. Dementia typically progresses to become worse over time.
How is dementia diagnosed?
In diagnosing dementia a doctor uses certain criteria. Criteria for the diagnosis of dementia include impairment of attention, orientation, memory, judgement, language, motor and spatial skills, and function. (By definition, dementia is not due to major depression or schizophrenia).
Dementia is not a disease itself, but rather a group of symptoms that are caused by various diseases or conditions. Symptoms can also include changes in personality, mood and behaviour. In some cases, the dementia can be treated and stopped or even reversed because the cause is treatable. Examples of this include dementia caused by substance abuse (illicit drugs and alcohol), combinations of prescription medicines, and hormone or vitamin imbalances. In some cases, although the person may appear to have dementia, a severe depression can cause the symptoms. This is known as pseudo-dementia (false dementia) and is highly treatable. In most cases, however, a true dementia cannot be cured.
Dementia develops when the parts of the brain that are involved with learning, memory, decision-making and language are affected by one or more of a variety of infections or diseases. The most common cause of dementia is Alzheimer’s disease, but there are as many as 50 other known causes. Most of these causes are very rare.
Because some causes of dementia can be cured or partially treated, it is very important that your doctor is thorough when making the diagnosis, so as not to miss potentially treatable conditions. The frequency of “treatable” causes of dementia is believed to be about 10%.
What causes dementia?
There are several things which could cause dementia:
- Diseases that cause degeneration or loss of nerve cells in the brain such as Alzheimer’s, Parkinson’s and Huntington’s.
- Diseases that affect blood vessels, such as stroke, known as vascular dementia
- Toxic reactions, like excessive alcohol or drug use.
- Nutritional deficiencies, like vitamin B12 and folic acid deficiency.
- Infections that affect the brain and spinal cord, such as AIDS dementia complex and Creutzfeldt-Jakob disease.
- Certain types of hydrocephalus, an accumulation of fluid in the brain that can result from developmental abnormalities, infections, injury or brain tumours.
- Head injury - either a single severe head injury or longer term smaller injuries, like in boxers.
- Illness other than in the brain - kidney, liver and lung diseases can all lead to dementia.
Alzheimer’s disease causes 50% to 60% of all dementias. But researchers have found that two nervous system diseases, which were originally incorrectly diagnosed as Alzheimer’s, are emerging as major causes of dementia: Lewy body disease and, less commonly, Pick’s disease.