What is dementia?

Dementia is an overall term for a set of symptoms that are caused by disorders affecting the brain. Symptoms may include memory loss and difficulties with thinking, problem-solving or language, severe enough to reduce a person's ability to perform everyday activities. A person with dementia may also experience changes in mood or behaviour.

Dementia is progressive, which means the symptoms will gradually get worse as more brain cells become damaged and eventually die.

Dementia is not a specific disease. Many diseases can cause dementia, the most common being Alzheimer's disease and vascular dementia (due to strokes). Some of the other causes of dementia include Lewy Body disease, head trauma, fronto-temporal dementia, Creutzfeldt-Jakob disease, Parkinson’s disease, and Huntington’s disease. These conditions can have similar and overlapping symptoms.

Some treatable conditions can produce symptoms similar to dementia, for example, vitamin deficiencies, thyroid disease, sleep disorders, or mental illness. It is therefore important to arrange for a full medical assessment as early as possible.

Getting a timely diagnosis can help you access information, resources and support through the Alzheimer Society, benefit from treatment, and plan ahead.

What’s the difference between Alzheimer’s Disease and dementia? If you have been confused by these terms in the past, or mistakenly thought that they were the same thing, watch the video:

The material was created by TCD, through the NEIL Programme at the Institute of Neuroscience with support from GENIO.

© 2014 The Provost, Fellows, Foundations Scholars, and the Other Members of Board, of the College of the Holy and Undivided Trinity Of Queen Elizabeth, near Dublin. Permission to use this material was granted by TCD which reserves all rights in the material.

Last Updated: 07/08/15
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