Having memory loss or cognitive impairment does not mean that you have Alzheimer's disease (AD).
Through a standard medical evaluation and diagnostic protocol, physicians often find that depression, a metabolic disorder, or other medications are impairing a patient's memory. By following published guidelines and ruling out other causes of memory loss, physicians can diagnose AD with better than 90% accuracy at an early stage of the progression.
Diagnosing Alzheimer's disease early and accurately is crucial because, for every month that treatment is delayed, there is irreversible loss of function. Current treatment of mildly-to-moderately demented AD persons with FDA-approved medication can delay AD progression meaningfully in some patients; the earlier treatment is started the more effectively the progression of AD is blocked, and the longer it is delayed.
Below are suggested steps to get the right diagnosis:
You should take seriously any concerns you express about difficulties with memory, communication, or decision making. Some form of assessment should be performed prior to the determination that you are "merely experiencing age-related decline."
If it is clearly established that your memory is declining or other cognitive symptoms are present, the diagnostic process should include neuropsychological testing to identify each and every realm of cognitive difficulty.
There are many conditions that can influence the function of the brain. A comprehensive review of the patient's medical history and family medical history will encourage the physician to investigate all possible contributing causes of the present symptoms.
Given the prevalence of depression, drug/alcohol use, thyroid disease, and poly-therapy, treatable causes of memory loss are quite common. Furthermore, only about 15% of Alzheimer's patients are completely free of other medical conditions that also impair memory and cognition. A proper diagnosis will capture all co-existing conditions and ensure proper treatment for the full range of problems.
While many causes of memory loss can be identified in the patient history and blood work, imaging is also an important step in the process for some patients. A structural MRI can show atrophy due to advancing AD and a PET scan can show loss of activity in certain brain regions at a much earlier stage.
While diagnosing AD is often characterized as a process of exclusion, the accuracy of the process is known to be better than 90% when a careful clinician follows published diagnostic guidelines. The common claim in the popular press that "AD can only be definitively diagnosed by autopsy" is true but should not be interpreted too severely. A clinically acceptable diagnosis can be achieved even in early stages of the disease.