Memory problems are a typical symptom of early Alzheimer’s disease and the starting point for medical investigations. Doctors use a combination of diagnosis methods to effectively rule out other conditions and accurately assess the probability that someone experiencing cognitive decline has Alzheimer’s. Over time, doctors can confirm the diagnosis by observing the natural progression of the disease and its cognitive and behavioral impact.
General Health Assessment
Recurrent memory problems such as being unable to remember a friend’s name or misplacing items can be an early sign of Alzheimer’s disease. But first, it’s important to rule out other possible causes.
Memory problems are usually self-reported, or else they are reported by family members or close friends. In some cases, memory lapses and other behaviors indicative of Alzheimer’s are more obvious to others than to the person diagnosed with the condition.
Either way, doctors begin with a general assessment of your health that includes questions about any recent changes in your behavior and personality. Doctors will usually also ask about whether you use any prescription or over-the-counter medication or have other symptoms.
Don’t be surprised if your doctor asks about your diet, too. A diet high in cholesterol and saturated fat may cause memory loss.
Physical and Neurological Exams
After the initial assessment, doctors carry out physical and neurological exams that test your reflexes, muscle tone, strength, coordination, balance, sight, and hearing. You may be asked to get up from a chair and walk across the room.
A basic neurological exam can point out other conditions that may cause memory and other cognitive problems. In some cases, it may also help diagnose Alzheimer’s disease in its more advanced stage, when it may cause problems with judging distances and maintaining one’s balance.
Alzheimer’s Disease Cognitive Tests
Cognitive tests focus on memory, attention, language, and problem-solving. They can help confirm memory loss and other signs of cognitive decline associated with Alzheimer’s disease. But again, no cognitive test can accurately tell that a person has Alzheimer’s or rule out other conditions that may present similar symptoms.
Cognitive tests may also point to Mild Cognitive Impairment (MCI), an intermediary stage between the normal cognitive decline associated with age and the onset of dementia. MCI causes problems with memory, thinking, judgment, and language and can be a risk factor for dementia. MCI may appear up to eight years before a person develops Alzheimer’s disease.
Psychological tests can diagnose depression. What does depression have to do with Alzheimer’s? Depression may cause cognitive impairment or be concurrent with Alzheimer’s disease.
Psychological testing may include the Geriatric Depression Scale (GDS), the Beck Depression Inventory (BDI), and the Hamilton Depression Rating Scale (HAM-D). These written tests involve questions that you have to answer with “yes” or “no” or by choosing among multiple answers.
In some cases, you may be referred to a psychiatrist for further testing to rule out depression or to determine whether depression exists alongside some other condition.
Alzheimer’s Disease Lab Tests
Blood and urine tests can further rule out other conditions that may cause memory problems or symptoms associated with dementia. Hypothyroidism, vitamin B-12 deficiency, or certain brain diseases may cause dementia-like symptoms, and lab tests can help diagnose them.
Scientists are also studying biomarkers that can accurately predict the presence of the disease, such as beta-amyloid or tau levels. In the future, biomarkers detectable through blood tests may provide a faster way to diagnose Alzheimer’s disease. At this point in time, however, there are no validated markers for identifying Alzheimer’s.
Your doctor may order a brain scan as well to eliminate other possible diseases. Brain scans can rule out trauma, strokes, or tumors, all of which may cause cognitive changes even if they don’t present with other obvious symptoms.
Depending on the symptoms, doctors may perform a CT scan, an MRI scan, or a PET scan. Unlike other forms of scanning, MRI (magnetic resonance imaging) does not involve radiation. It may be the preferred type of scanning unless your doctor believes that it cannot yield results as accurate as a CT scan.
PET scans are the most detailed, but they also come with a higher dose of radiation, so doctors will not usually start with a PET scan unless they have a very good reason for doing so. Fluorodeoxyglucose PET imaging and Amyloid PET scans may help doctors see changes in the brain that enable them to differentiate between Alzheimer’s and other dementias.
In the future, brain scans may also help to detect Alzheimer’s more quickly. But currently, the use of specific imagining applications is largely limited to research centers.
Cerebrospinal Fluid Tests (CSF)
CSF tests are generally used to identify conditions affecting the brain or spine or certain forms of cancer. They are not part of the standard Alzheimer’s disease diagnosis process, but doctors may prescribe them for patients who show signs of early-onset Alzheimer’s disease. Cerebrospinal fluid tests for Alzheimer’s look at beta-amyloid and tau concentrations.
Genetic Risk Profiling For Alzheimer’s Disease
In families with a high incidence of Alzheimer’s disease, doctors may use genetic risk profiling to identify risk-carrying genes, such as the APOE-e4. However, genetic profiling is also limited to research settings as identifying the presence of these genes does not yet facility new treatments. At any rate, genetic risk profiling is not so much a diagnosis method as a risk assessment.
Tests to Rule Out Other Forms of Dementia
After all these tests, doctors can confidently rule out other conditions that may cause early dementia-like symptoms. But they may still have to determine whether it’s Alzheimer’s disease that’s causing the symptoms or some other form of dementia.
To accurately differentiate Alzheimer’s from other forms of dementia, doctors generally use advanced neuropsychological testing. While all forms of dementia may cause cognitive changes in the early stage, not all necessarily cause recurrent memory problems.
Doctors also use their understanding of how dementia progresses to come to an accurate diagnosis. For example, both Alzheimer’s and dementia with Lewy bodies can cause hallucinations. But in the latter, hallucinations appear in the early stage of the condition, while in Alzheimer’s they appear in later stages.
Alzheimer’s may also occur concurrently with other forms of dementia, in which case doctors will try to identify both. This condition is known as mixed dementia.
When diagnosing dementia, doctors use the following terms:
- Probable Alzheimer’s disease—dementia has been established between ages 40-90 years and cognitive impairments are progressive.
- Possible Alzheimer’s disease—the dementia syndrome has an atypical presentation, onset, or progression.
- Unlikely Alzheimer’s disease—the dementia syndrome has a sudden onset and includes seizures, focal neurological signs, or problems walking.
The Bottom Line
Diagnosing Alzheimer’s disease is a process that can take time. It may involve self-assessment as well as interviews with friends and family. While there is no single diagnosis method currently available that can quickly identify the condition, doctors have many tools that they can use to effectively rule out other similar diseases.
In the future, new ways of diagnosing Alzheimer’s disease could provide a faster, more accurate diagnosis that enables better treatment and helps manage stress. Non-invasive Alzheimer’s disease diagnosis tests such as the one our team is working on could make a positive impact in many people’s lives. We feel proud to be part of the effort to find a faster, easier way to diagnose Alzheimer’s disease in its early stage.