Diagnosing Alzheimer's Disease - Symptoms and Signs

AD Diagnosis

As with many neurological diseases there is no single definitive test to diagnose Alzheimer’s.

Some people claim that the only way to diagnose the condition is at a post mortem when the brain can be looked at in great detail. Others claim that this just confirms a diagnosis and the disease is obvious once it gets into the later stages.

It’s quite a complex disease and often there can be difficulty in distinguishing (especially at its early onset) it from other forms of dementia such as Pikes disease, Parkinson’s or Creutzfeldt-Jakob disease (the latter more commonly known as Mad Cows’ Disease).

So diagnosing Alzheimer’s is really down to the skill of the doctor. He or she first has to rule out depression, alcoholism and the side effects of medications which could all produce similar symptoms but, importantly, are treatable.

Signs of Alzheimer’s – Early Onset

In the early stages it’s very difficult to diagnose Alzheimer’s as the symptoms are vague. Usually people consult a doctor during the later stages when the symptoms and signs are more obvious and causing worry both to the sufferer and their family. Up until that point the symptoms might be attributed to old age - or the potential diagnosis may be too frightening for a family to contemplate.

Before making a diagnosis of Alzheimer’s the doctor will look at whether the patient’s behavior and function fits in with previous behavior. The doctor should ask to see both the person suspected of having Alzheimer’s and those close to them to discover what the symptoms are and how family and friends view their current mental and physical condition. A full medical history will be taken, focusing on previous and current health problems and any medications being taken.

A mental evaluation will also be undertaken to assess a person’s ability to understand, remember, talk, add up and subtract. The patient may be asked to do spelling tests, memory tests, draw an object or asked simple questions such as “who is the Prime Minister?”, “what year is it?” or “what day comes after Friday?”

There will be a thorough physical examination to rule out any other conditions such as stroke or heart disease which may produce Alzheimer-type symptoms.

A neurological examination to test reflexes, co-ordination, strength, eye movement and balance will also be carried out.

Computer Tests for Diagnosing the Disease

Some doctors may ask for a special electroencephalogram (EEG) to see whether there is any abnormal brain activity. While this may not indicate Alzheimer’s it could diagnose epilepsy which produces similar dementia type symptoms.

A computer tomography (CAT) scan or magnetic resonance imaging (MRI) scan which take detailed images of the brain are sometimes used but again these are more to rule out other conditions than to diagnose Alzheimer’s.

Some of the newer scans and computer tests such as positron emission tomography (PET) - which highlights how the brain responds when a person performs a task - and single proton emission computed tomography (SPECT) - which shows the flow of blood to the brain and indicates areas the blood isn’t getting to - are becoming incredibly useful in helping to arrive at an Alzheimer’s diagnosis.

Although there are some changes in the brain that can be seen on these scans they can’t lead to a definitive diagnosis as other conditions can cause similar symptoms.

The diagnosis is based on the results of several different tests.


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