Dementia – Dementia is a general term for loss of memory, language, problem-solving and other thinking abilities that are severe enough to interfere with day-to-day life. Alzheimer’s is the most common cause of dementia.
Dementia is not a single disease; it’s an overall term — like heart disease — that covers a wide range of specific medical conditions, including Alzheimer’s disease. Disorders grouped under the general term “dementia” are caused by abnormal brain changes. These changes trigger a decline in thinking skills, also known as cognitive abilities, severe enough to impair daily life and independent functions. They also affect behaviour, feelings and relationships.
Alzheimer’s disease accounts for 60-80% of cases.
Vascular dementia, which occurs because of microscopic bleeding and blood vessel blockage in the brain, is the second most common cause of dementia. Those who experience the brain changes of multiple types of dementia simultaneously have mixed dementia. There are many other conditions that can cause symptoms of dementia, including some that are reversible, such as thyroid problems and vitamin deficiencies.
Signs of dementia can vary. Examples usually include:
- Problems with short-term memory.
- Traveling out of the neighbourhood.
- Keeping track of keys or wallet.
- Planning and preparing daily meals.
- Remembering appointments, paying bills and birthdays.
Dementia is caused by damage to brain cells. This damage interferes with the ability of brain cells to communicate with each other. When brain cells cannot communicate normally, thinking, behaviour and feelings can be affected. The brain has many distinct regions, each of which is responsible for different functions (for example, memory, judgment and movement). When cells in a particular region are damaged, that region cannot carry out its functions normally.
Different types of dementia are associated with particular types of brain cell damage in particular regions of the brain. For example, in Alzheimer’s disease, high levels of certain proteins inside and outside brain cells make it hard for brain cells to stay healthy and to communicate with each other. The brain region called the hippocampus is the center of learning and memory in the brain, and the brain cells in this region are often the first to be damaged. That’s why memory loss is often one of the earliest symptoms of Alzheimer’s.
There is no test to determine if someone has dementia. Doctors diagnose Alzheimer’s and other types of dementia based on a careful medical history, a physical examination, laboratory tests, and the characteristic changes in thinking, day-to-day function and behaviour associated with each type. Doctors can determine that a person has dementia with a high level of certainty. But it’s harder to determine the exact type of dementia because the symptoms and brain changes of different dementias can overlap.