Alzheimer’s disease is a progressive brain disorder that causes problems with memory, thinking, and behavior. Detecting Alzheimer’s early is important, as starting treatment in the disease’s early stages may help preserve daily functioning for some time. But how do doctors test for early signs of Alzheimer’s?
What are the early signs of Alzheimer’s disease?
Some early signs and symptoms of Alzheimer’s include:
- Memory problems, like forgetting recently learned information or important dates and events
- Increasing confusion with time, location, or people’s identities
- Difficulty with visual and spatial abilities, like reading or judging distance
- Trouble following or joining conversations
- Forgetting common words while speaking or writing
- Misplacing items often
- Decreased or poor judgment
- Withdrawal from work, family, and social activities
- Changes in mood or personality, like increased anxiety, suspicion, irritability, or apathy
These symptoms reflect the early stages of Alzheimer’s disease, when mild cognitive impairment begins disrupting daily life. However, they may also result from other conditions like depression, medication side effects, thyroid issues, or vitamin deficiencies. Doctors must investigate further to determine if Alzheimer’s is the cause.
Medical history and physical exam
If Alzheimer’s disease is suspected based on symptoms, the first steps are to take a medical history and perform a physical exam. The doctor will ask about:
- Current symptoms and when they began
- Medical conditions and past illnesses
- Prescription and over-the-counter medications being taken
- Family medical history, especially any dementia cases
The physical exam helps identify or rule out other potential causes of symptoms, like high blood pressure, heart problems, infections, nutritional deficiencies, tumors, or medication side effects. The doctor will check the patient’s:
- Heart, lungs, blood pressure, and other vital signs
- Reflexes, balance, senses, coordination, and muscle tone and strength
- Ability to feel vibrations from a tuning fork on the feet, which can indicate nerve damage
The physical exam allows the doctor to observe initial signs of Alzheimer’s, like difficulty following instructions, recognizing objects, speaking, or coming up with words.
Memory and cognitive testing
If the initial history and exam indicate Alzheimer’s as a possibility, the next step is more extensive cognitive testing. This can help detect mild cognitive impairment (MCI) or early dementia. Cognitive testing involves:
- Memory tests – The patient is asked to recall lists of words, stories, or objects after time delays ranging from a few minutes to several hours. Short-term and working memory are assessed.
- Attention and concentration tests – The patient performs mental tasks like subtracting 7s from 100 or spelling words backwards. Ability to focus is evaluated.
- Language tests – The patient names objects, repeats phrases, and answers open-ended questions. Speech and vocabulary are examined.
- Visuospatial tests – The patient copies geometric drawings or arranges puzzle pieces. Visual perception and spatial relationships are tested.
Results help compare the individual’s cognitive performance to normal ranges for their age. Significant difficulty with memory, thinking skills, problem-solving, and other tasks indicates abnormal cognitive decline that requires further assessment.
Medical tests to rule out other causes
In addition to cognitive testing, doctors will conduct medical tests to check for other conditions that could explain the symptoms:
- Blood tests – Test blood cell counts, vitamin levels, thyroid and liver function, and evidence of syphilis or HIV to uncover any correctable conditions.
- Brain imaging – CT or MRI scans detect strokes, tumors, head trauma, or accumulation of fluid. PET and SPECT scans measure brain activity and blood flow.
- Lumbar puncture (spinal tap) – Examines spinal fluid for signs of infection or other conditions affecting the brain.
These tests allow doctors to rule out other causes and gather more evidence for an Alzheimer’s diagnosis. However, they usually cannot confirm Alzheimer’s conclusively at this early stage.
Neuropsychological testing
After initial cognitive screening, a neuropsychological evaluation can provide detailed information on specific brain functions affected by early Alzheimer’s disease. Areas assessed may include:
- Memory – verbal and visual recall, recognition, working memory
- Language – naming objects, fluency, comprehension
- Attention – focus, concentration, multitasking
- Visuospatial skills – facial recognition, route finding, pattern matching
- Executive functions – planning, organization, self-monitoring
- Processing speed – reaction time and latency on cognitive tasks
This thorough testing can detect subtle deficits in cognitive domains that suggest Alzheimer’s pathology versus normal aging. It also establishes a cognitive baseline to track future decline.
Genetic testing
Genes known to increase Alzheimer’s risk include:
- Apolipoprotein E (APOE) gene – Having the APOE-e4 variant raises Alzheimer’s risk while APOE-e2 lowers it.
- APP, PSEN1, PSEN2 genes – Rare mutations in these genes virtually guarantee early-onset Alzheimer’s.
Genetic testing, usually from a blood or saliva sample, can identify these genetic risk factors. However, many people develop Alzheimer’s without high-risk genes. So genetic testing alone cannot diagnose the disease.
| Gene | Effects |
|---|---|
| APOE-e4 | Increases Alzheimer’s risk 3- to 15-fold |
| APOE-e2 | Lowers Alzheimer’s risk by up to 40% |
| APP, PSEN1, PSEN2 | Causes rare early-onset Alzheimer’s if mutated |
Preliminary diagnosis
Based on all testing results, the doctor may conclude that Alzheimer’s is the likely diagnosis, even in its early stages. However, Alzheimer’s can only be definitively diagnosed by examining brain tissue at autopsy. So at this point, the diagnosis may be:
- Mild cognitive impairment (MCI) due to Alzheimer’s disease – Marked cognitive decline for age and education level that does not yet severely disrupt daily functioning.
- Probable or possible Alzheimer’s dementia – Progressive cognitive deficits already interfering with daily activities.
These preliminary diagnoses indicate Alzheimer’s is the most likely explanation for the symptoms and cognitive deficits observed.
Monitoring progression
After a preliminary Alzheimer’s diagnosis, doctors will want to monitor the individual closely over time. This can confirm that symptoms worsen gradually, as expected with Alzheimer’s. Tools for monitoring disease progression include:
- Follow-up cognitive tests – Repeating standardized tests periodically shows if thinking and memory skills continue to decline.
- Brain imaging – Repeated PET, MRI, and CT scans reveal progressive atrophy, reduced activity and blood flow in Alzheimer’s disease.
- Lab tests – Changing levels of tau protein and beta-amyloid in the spinal fluid confirm Alzheimer’s pathology.
- Clinical dementia rating scale – The doctor regularly assesses language, memory, judgment and other cognitive functions to quantify increasing impairment.
Worsening test results over time strengthen the likelihood that Alzheimer’s is the correct diagnosis. Monitoring progression also helps guide treatment and care planning.
Probable Alzheimer’s diagnosis
After other dementias have been ruled out and cognitive decline progresses as expected over months or years, a doctor makes a “probable Alzheimer’s disease” diagnosis. This clinical diagnosis currently has over 90% accuracy when verified at autopsy according to research studies.
This diagnosis signals that treatments, planning for worsening impairment, and support services should be put in place for the Alzheimer’s patient and their family.
Treatment options at this stage
While Alzheimer’s has no cure yet, available treatments can temporarily improve or stabilize symptoms when started early. Treatment options include:
- Cholinesterase inhibitor medications to improve memory and thinking skills
- NMDA receptor blockers to slow cognitive decline
- Antidepressants for depression, anxiety, and sleep problems
- Cognitive rehabilitation and memory training therapies
- Counseling and support groups for patients and families
Early treatment maximizes remaining brain function and delays progression of disability. It can make a significant difference in quality of life.
Conclusion
Testing for early Alzheimer’s disease involves medical history, physical exam, cognitive assessments, lab tests, brain imaging, and genetic analysis to rule out other causes. A diagnosis of mild cognitive impairment or probable Alzheimer’s dementia can be made based on progressive cognitive deficits interfering with daily function. Regular monitoring with cognitive testing, brain scans, and other tools confirms worsening typical of Alzheimer’s versus other conditions. Starting treatment and planning early while some brain function remains provides the best outcomes for patients and families facing this challenging diagnosis.