There are no quick, simple, reliable, inexpensive and noninvasive tests available to diagnose Alzheimer's disease, before the individual suffers significant damage. Diagnosis of Alzheimer's rests largely on the judgment of physicians experienced in dealing with similar illnesses.
The hallmarks of Alzheimer's disease is plaques and tangles in brain tissue. However this cannot be used to establish a diagnosis as it is seen only after an autopsy . Getting the right diagnosis is the first step in planning any treatment.
There are other causes of dementia that requires to be ruled out before labeling a patient as suffering from Alzheimer's disease. Some of these are reversible and include thyroid and Vitamin deficiencies. About 60% of dementia is due to Alzheimer's and about 15% are related to vascular diseases. There is also a category where there is mix of both Alzheimer's and vascular disease. A new entity has recently been added called 'Lewy Body disease' that can also cause dementia.
A complete physical and neurological examination is the first step before investigations are undertaken. After this the patient requires a psychiatric assessment. It is important for someone close to the patient to be interviewed to learn about the patient's daily activity and understand their emotional state.
Ruling out Parkinson's disease, stroke or tumors of the brain is essential. Memory tests are undertaken for recall of events.
Once the physical and mental assessment is over, blood tests and radiological investigations are done to rule out anemia and vitamin deficiency. Tests related to the thyroid kidney and liver are also carried out.
The brain imaging is done using CT scan or MRI or the newer PET scan to understand if there are any apparent changes in the overall size of the brain and the memory associated areas of the brain such as hippocampus.
Sometimes it may be essential to undergo an EEG test of the brain where the signals are picked up by recorder and analyzed. A spinal tap to analyze the CSF fluid may also need to be done
Alzheimer disease causes deposition of plaques that contain an insoluble protein called beta amyloid. Under the microscope one can recognize the presence of these "neurofibrillary tangles" due to a protein called 'Tau'. T his protein encourages the formation of microtubules and these transport chemicals inside cells. Tangles are the hallmark of Alzheimer's but Tau is also a suspect in causing the disease.
|A woman, 51 years old, showed jealousy toward her husband as the first noticeable sign…. Soon a rapidly increasing loss of memory could be noticed. She could not find her way around in her own apartment…. Her entire behavior bore the stamp of utter perplexity. She was totally disoriented to time and place…. The generalized dementia progressed…. After 4 1/2 years…death occurred…. The autopsy revealed a generally atrophic brain without macroscopic lesions…. Scattered through the…cortex…one found miliary foci that were caused by the deposition of a peculiar substance.
Alois Alzheimer, 1907