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What's the difference between Alzheimer's disease and dementia?

By: Dr. Marla Davidson

Dementia is a term used to describe changes in thinking that make it more difficult to perform everyday activities. The term dementia describes a group of brain disorders that include Alzheimer’s disease, vascular dementia, mixed dementia, frontotemporal dementia, lewy body dementia, and Parkinson’s disease. Alzheimer’s disease is the most common cause of dementia accounting for 65% of all dementias.

What is Alzheimer’s disease?


Alzheimer’s disease is a progressive, degenerative disease of the brain and is a type of dementia. It is not a part of normal aging. Alzheimer’s disease is associated with typical changes in the brain, often referred to as “plaques,” “tangles” and brain shrinkage. Its progression differs from the other types of dementia. Alzheimer’s disease is characterized by a slow, gradual decline. Short-term memory problems are usually the first symptom or sign of Alzheimer’s disease.  Individuals experience forgetfulness that occurs much more frequently and persistently than that associated with normal aging. Common complaints include difficulty remembering appointments, conversation details or aspects of television programs. Family members and caregivers notice that the individual may repeat questions or stories and misplace things. In the initial phase of the disease there are language problems such as difficulty finding specific words, naming objects, and constructing informative sentences. Individuals may begin to experience changes in their mood and behaviour.  The illness impacts their thinking and impairs their judgment.  Visuospatial skills may also be affected which results in difficulty navigating unfamiliar environments resulting in the individual getting lost. As the disease progresses it begins to affect an individual’s day-to-day functioning and their ability to carry out motor functions resulting in them requiring full-time care. 

Alzheimer’s dementia generally progresses along a typical pattern allowing it to be divided into 3 stages based on the individual’s cognitive and functional abilities. The stage of the disease is important because it helps with diagnosis and helps to predict the types of behaviours or psychiatric symptoms a person with Alzheimer’s disease may experience during the course of their illness. Despite Alzheimer’s disease having a typical pattern the progression of the illness differs from person to person. We are unique individuals with different experiences, levels of education, skills, and abilities therefore the disease affects each of us differently resulting in variations in the presentation of the symptoms.

Mild (Early) Stage: Needs help with instrumental activities of daily living (iADLs) which include driving, banking, administering medications, housekeeping, and grocery shopping. May see changes in mood (depression) or anxiety.

Moderate (Middle) Stage: Needs some help with activities of daily living (ADLs) which include bathing, dressing, grooming, eating, and toileting. May see changes in behaviour such as restlessness (pacing), uninhibited behaviour (from overtly sexual behaviours to aggression). Individuals may experience delusions (beliefs that aren’t true) or hallucinations (hearing, seeing, smelling or tasting things that aren’t there) during this stage.

Severe (Late) Stage: Needs full care. Individual has more difficulty communicating and is more physically frail.

It is a common misperception that memory problems are a part of normal aging. As we age it does take longer to remember facts and details but memory problems that affect short-term recall resulting in a person being more repetitive or misplacing things are not a part of normal aging.  Memory changes that are a part of normal aging do not impact our ability to get day-to-day tasks done. When memory changes begin to impact our ability to function it can be a warning sign of dementia. 

If you or someone you know is experiencing any warning signs or symptoms it is important to see a doctor for a complete assessment.

How is dementia diagnosed?

There is no blood tests or brain scan that can diagnose dementia.  Blood tests may be ordered to look for other medical illnesses or nutritional problems. Some people will have a CT scan or MRI of their brain but it is not required for the diagnosis of dementia. Dementia is not diagnosed by a specific cognitive test.  “Memory testing” is used to look for dementia.  Dementia is diagnosed based on the clinical presentation of cognitive symptoms and their impact on function.

Dr. Davidson is a geriatric psychiatrist and clinical assistant professor in the Department of Psychiatry at the University of Saskatchewan. She is also a member of the Alzheimer Society of Saskatchewan Board of Directors, lending her experience with dementia to helping guide our work.

Have more questions? Call the Dementia Helpline: 1-877-949-4141

Last Updated: 11/08/2017