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Dementia

How do doctors diagnose dementia?

It can be difficult for doctors to tell if someone has dementia, especially in the early stages.

There's no test that can tell someone that they definitely have

Alzheimer's disease
People who have Alzheimer's disease slowly lose their memory and ability to think clearly. As the disease gets worse, they get more confused and start acting differently. Several changes happen in the brain that stop it working properly. Small lumps called amyloid plaques grow in the parts of the brain used for memory and thinking. And bundles of twisted threads called 'neurofibrillary tangles' form inside brain cells. These stop brain cells communicating with each other, and they can cause cells to die. Also, in Alzheimer's disease, the brain does not have enough chemical messengers (neurotransmitters), and holes or gaps appear where brain cells have died.

Alzheimer's or another type of dementia. But there are tests that can help doctors decide whether it's likely that someone has one of these conditions.

The early signs of dementia are easy to miss. And there's no way of knowing exactly when it starts unless someone develops dementia due to a

stroke
You have a stroke when the blood supply to a part of your brain is cut off. This damages your brain and can cause symptoms like weakness or numbness on one side of your body. You may also find it hard to speak if you've had a stroke.

stroke. Scientists are trying to find ways of spotting dementia early on. It's helpful if people with dementia can plan for the future while they can still take part in decisions.

Getting a checkup

If you think that someone in your family might have Alzheimer's or another type of dementia, you should make sure they get a detailed checkup with a doctor specializing in brain disorders. This might be a

neurologist
A neurologist is a doctor who specializes in the diagnosis and treatment of diseases that affect your brain and your nervous system.

neurologist, a

psychologist
A psychologist is trained to study the human mind and human behaviour. A clinical psychologist provides mental health care in hospitals, clinics, schools or to private patients.

psychologist, a

geriatrician
A geriatrician is a doctor who specializes in treating older people.

geriatrician or a

psychiatrist
A psychiatrist is a medical doctor who specializes in psychiatry, a branch of medicine that covers the science and practice of treating mental, emotional or behavioral disorders.

psychiatrist.

You may find that they don't want to see a doctor about their symptoms. But you might be able to persuade them to go for a physical checkup or for help with a specific problem, such as not being able to get to sleep. As the symptoms change over time, it's important to have regular checkups with a specialist doctor.

Source:
McKeith I.
The differential diagnosis of dementia.
In: Burns A, Levy R. Dementia. 1st edition. Chapman and Hall, London, UK; 1994.

When doctors first see someone who gets confused or has problems with memory, they need to rule out other things that can cause these symptoms.

depression
Depression is a mental illness in which your mood is low and you feel sad much of the time. It can range from a mild illness through to a severe one in which you lose interest in life and may be suicidal.

Depression and other conditions can cause symptoms of dementia (see Causes of dementia to learn more). It's important that other conditions are spotted and treated if possible.

Source:
Bouchard RW, Rosser MN.
Typical clinical features.
In: Gauthier S. Clinical diagnosis and management of Alzheimer's disease. Martin Dunitz, London, UK; 1999.

² And some people may have two types of dementia at the same time. For example, someone may have Alzheimer's and

vascular dementia
This type of dementia happens when blood vessels near your brain get damaged, so your brain doesn't get enough blood. Some of the cells in your brain die, which causes symptoms such as confusion and memory problems. Vascular dementia can happen suddenly if you have a stroke. Or it can come on gradually if you have a series of little strokes (this is called multi-infarct dementia).

vascular dementia. This can make it difficult to accurately diagnose what is causing their symptoms.

Source:
Pryse-Phillips W, Galasko D.
Non-alzheimer's dementias.
In: Gauthier S. Clinical diagnosis and management of Alzheimer's disease. Martin Dunitz, London, UK; 1999.

Questions and tests

When doctors first see someone who might have Alzheimer's or another type of dementia, they may:

Ask about the person's medical history
Examine the person physically and take samples of their blood and urine to rule out other diseases
Do some tests of memory, language or reasoning
Do an

MRI scan
The magnetic resonance imaging (MRI) machine uses a magnetic field to create detailed pictures of the inside of the body. These pictures allow doctors to look at parts of the body in three-dimensional images.

MRI scan or a

CT scan
A CT scan is a type of X-ray. It takes several detailed pictures of the inside of your body from different angles. CT stands for computed tomography. It's also called a CAT scan (computed axial tomography).

CT scan to check if a person has had a stroke or has cancer.

Doctors often use a test called the Mini-Mental State Examination (or MMSE for short). It's a series of questions that test someone's memory, understanding and ability to carry out simple tasks. The test results help doctors decide how bad someone's dementia is. This test is often used in research studies to see whether treatments for dementia are working.

Sources for the information on this page:

McKeith I.The differential diagnosis of dementia.In: Burns A, Levy R. Dementia. 1st edition. Chapman and Hall, London, UK; 1994.

Bouchard RW, Rosser MN.Typical clinical features.In: Gauthier S. Clinical diagnosis and management of Alzheimer's disease. Martin Dunitz, London, UK; 1999.

Pryse-Phillips W, Galasko D.Non-alzheimer's dementias.In: Gauthier S. Clinical diagnosis and management of Alzheimer's disease. Martin Dunitz, London, UK; 1999.

This information was last updated on Mar 05, 2009

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment.
© BMJ Publishing Group Limited 2009. All rights reserved.

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