There are several methods and diagnostic tools to help determine fairly accurately whether an individual with memory problems has “possible Alzheimer’s disease,” “probable Alzheimer’s disease,” or some other memory or neurological problem. “Possible Alzheimer’s disease” is defined as a dementia that could be due to another condition. “Probable Alzheimer’s disease” means there are no other causes for the symptoms that can be found. Some individuals with memory problems have a condition called amnestic mild cognitive impairment (MCI) that often precedes AD. Individuals with MCI have more memory problems than normal for individuals their age, but their symptoms are not as severe as those seen in AD. Importantly, not all individuals with MCI develop AD. At this time, a definitive diagnosis of Alzheimer’s disease can only be determined by an autopsy of the brain after death. However, at specialized centers, such as the NIA-funded Alzheimer’s Disease Centers, doctors can diagnose AD in a living person correctly up to 90 percent of the time.
A physician will diagnose Alzheimer’s in a living person by:
- Asking questions about an individual’s overall health, past medical history, ability to perform daily activities, and changes in behavior and personality
- Conducting memory tests, problem solving, attention, counting, language skills and other abilities related to brain functioning
- Carrying out medical tests of blood, urine, or spinal fluid
- Collecting information provided by family members or other caregivers about changes in a person’s day-today function and behavior which my help in diagnosis
- Performing brain scans, such as magnetic resonance imaging (MRI), positron emission tomography (PET) scan or a computed tomography (CT) scan
These tests are often repeated annually to give doctors an idea about how the individual’s health and memory may be changing over time. Often these tests assist doctors in finding other possible causes of an individual’s symptoms. For example, depression, brain tumors, thyroid problems, drug reactions, and blood-vessel disease in the brain can cause Alzheimer’s-like symptoms. Some of these other conditions can be treated successfully.
An early and accurate diagnosis is crucial because it tells people whether they have Alzheimer’s disease or whether their symptoms are caused by something else. Stroke, tumor, Parkinson’s disease, sleep disturbances, or side effects of medications are all known to affect cognitive function and memory, and some of these conditions are reversible. When AD is diagnosed, knowing early on can help patients and their families plan for the future. It gives families time to discuss care options while the patient can still take part in making decisions. Researchers are developing increasingly accurate diagnostic tests for telltale biomarkers that may one day be used in general medical practice to detect the disease before memory loss or cognitive impairment is evident. Early diagnosis also offers the best chance to treat the symptoms of the disease.