Common Types of DementiaThe term dementia is used broadly to describe a condition which is characterized by cognitive decline, but there are many different types of dementia. Although the disease is usually progressive, a proper and specific diagnosis can indicate treatments that will reverse the effects and at times even lead to a cure by addressing the underlying cause. However, dementia caused by incurable conditions, such as Alzheimer’s disease, is irreversible.

Dementia is caused by various diseases and conditions that result in damaged brain cells or connections between brain cells. When making a diagnosis of dementia, physicians commonly refer to the following criteria:

Symptoms of Dementia

  • Symptoms must include decline in memory and in at least one of the following cognitive abilities:
    Day-to-day memory
    Visuospatial skills (“visuo” referring to eyesight and “spatial” referring to space or location), which give a person the ability to interpret objects and shapes.
  • The decline in cognitive abilities must be severe enough to interfere with daily life.

Mild Cognitive Impairment

Some individuals with memory problems and a decline in cognitive abilities have a condition called amnestic mild cognitive impairment (MCI) that often precedes Alzheimer’s disease (AD). Individuals with MCI have more memory problems than normal for individuals their age, but their symptoms are not as severe as those seen in AD. Importantly, not all individuals with MCI develop AD.

In MCI, these symptoms will have been noticed by the individual and those who know them. If the person with MCI has taken cognitive function tests, their problems will be seen in test results over time. Any decline will be greater than the gradual decline that many people experience as part of normal, healthy ageing. There may be minor problems with more demanding tasks, but generally not problems in everyday living (if there is a significant impact on everyday abilities, this may suggest dementia).

Memory loss and other cognitive problems can arise from many different causes. For some people diagnosed with MCI, memory loss will be the first sign of Alzheimer’s disease. For some of those with other cognitive problems, these will be the first signs of vascular dementia, frontotemporal dementia, or dementia with Lewy bodies.

It is important for a physician to determine the cause of memory loss or other dementia-like symptoms. Some symptoms can be reversed if they are caused by treatable conditions, such as depression, delirium, drug interaction, thyroid problems, excess use of alcohol, or certain vitamin deficiencies.

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