The Medical Diagnosis: Alzheimer's

A medical diagnosis of Alzheimer's relies on a number of factors. Alzheimer's symptoms must be documented, and family members interviewed. A complete physical exam and medical history must be taken, including blood tests to rule out other causes of dementia. Brain imaging tools may be used to help make a medical diagnosis.

 

The only sure way to diagnose Alzheimer's is to examine brain tissue after death. A medical diagnosis of Alzheimer's disease in a living patient is divided into two categories: possible and probable. A diagnosis of "possible" Alzheimer's indicates that while symptoms may be caused by the disease, the diagnosis was unable to rule out alternative causes. A "probable" medical diagnosis indicates all other alternatives have been discounted.

A list of symptoms will be compiled during diagnosis, including memory loss, language difficulties, and personality changes. People suffering from memory impairment and other symptoms of Alzheimer's often under report the severity of their symptoms. Family members should meet with the examining doctor and report any symptoms or signs of memory loss they have noticed.

Clinical tests, such as the Mini-Mental State Examination (MMSE), are used to evaluate memory and cognitive function. While such tests are helpful and provide information about the severity of symptoms, they cannot be used alone to make a medical diagnosis.

Blood tests are used to rule out secondary causes of dementia symptoms. Kidney function, liver function, and hormone imbalances may all be detected by blood tests. Blood tests are also used to check for electrolyte imbalances, diabetes, and vitamin deficiencies, which can also result in Alzheimer's symptoms.

Imaging tools, such as CT and PET scans are used to rule out physical causes of dementia symptoms. Scans may reveal blood clots, brain tumors, and evidence of strokes.

 

A CT scan uses multiple x-rays to take pictures of the brain. Occasionally, brain tissue deterioration can be observed by a simple CT, however, this usually indicates that the disease is in an advanced stage.

 

A PET scan may provide a way to make an earlier Alzheimer's diagnosis. A PET scan works much like a CT scan, but radiolabeled metabolites are injected into the bloodstream and actually show up on the images. This allows the radiologist to see how well the brain is working. Active areas of the brain are highlighted on a PET scan, while areas of degeneration are dark.

 

An EEG may reveal slower than normal brain waves, a possible indication of Alzheimer's disease.

Spinal taps may reveal the presence of tau or beta amyloid proteins in spinal fluid. Both proteins are associated with Alzheimer's disease. Clinical trials are exploring the possibility that the presence of these proteins in spinal fluid may be used to make a definitive medical diagnosis. If so, it may become possible to diagnosis Alzheimer's in its earliest stages, allowing for earlier medical interventions.

 

University of Michigan Health System. (2002, October 31). Seeing into the Alzheimer's brain: U-M researchers say PET scans can help diagnosis, treatment. U-M Press Release.