People who are concerned about changes in how they think, feel, and behave — also known as cognitive changes — may wonder how to go about getting tested to find out whether there’s really a problem and what might be causing it.
The first step, for many people, is talking to your primary care doctor about your concerns. Your regular doctor can give you a cognitive screening test and, depending on the results, may recommend that you see a specialist for further testing.
Your doctor may refer you to a neurologist — a specialist in disorders of the brain and nervous system. In some cases, a geriatric psychiatrist, a neuropsychologist, or a geriatrician may be more available and have the expertise to make a diagnosis.
Diagnosis of dementia and the brain changes that cause it generally involves a medical history, a physical exam, lab tests, and neuropsychological tests. While doctors can usually diagnose dementia with a high degree of confidence, identifying the underlying cause can be more challenging.
One reason it can be hard to identify the cause or type of dementia is that symptoms of different conditions overlap. What’s more, people may have more than one type of dementia at the same time.
Despite these difficulties, an accurate diagnosis is an essential first step in getting the care you need.
For example, people with Lewy body dementia may respond differently to drugs prescribed for other forms of dementia like Alzheimer’s, so it’s important to know if someone has this form of dementia before deciding on a course of treatment.
At the same time, it’s important to be realistic about the challenges involved in diagnosing dementia. It’s likely that you’ll need a series of tests to figure out what condition you have, according to Mayo Clinic. This process can take a few weeks for some people, but months or even longer than a year for others.
One of the first priorities in diagnosing any type of dementia is ruling out treatable or reversible causes of cognitive difficulties. These may include:
Normal pressure hydrocephalus (NPH), a buildup of fluid in the brain
Side effects of medications
Thyroid, adrenal, or other endocrine conditions
Exposure to heavy metals, such as arsenic or mercury
Vitamin deficiencies, such as inadequate amounts of B vitamins
It’s particularly important for your doctor to review your medications if you’re experiencing any cognitive difficulties, according to Cleveland Clinic. Medications that may cause dementia-like symptoms include sleeping pills and sedatives, narcotic pain relievers, statins (used to treat high cholesterol or triglycerides), and certain drugs used to treat depression, anxiety, seizures, and Parkinson’s disease.
Researchers are working to develop tests that can identify people on course to develop dementia before the onset of symptoms. They are also working to diagnose dementia at its earliest stages, with the goal of slowing brain damage through early treatment.
Part of this effort involves a search for biomarkers — indicators of disease that can be measured accurately and reliably, such as through imaging scans or measuring substances in blood or cerebrospinal fluid (CSF).
Right now, certain substances in cerebrospinal fluid can be measured to help diagnose Alzheimer’s disease and other forms of dementia. This is done through a lumbar puncture, also known as a spinal tap — a procedure that involves inserting a needle into your spinal canal to collect fluid.
Blood tests to identify dementia are still under development, but several promising testing protocols have been identified. For example, a blood test looking at one measure of tau (a component of brain tangles in Alzheimer’s disease) was found to be equivalent to or better than currently used tests involving cerebrospinal fluid.
If your doctor suspects you have Alzheimer’s disease — the most common form of dementia — a number of methods may be used to arrive at a diagnosis.
First, your doctor will look at your medical history and administer a physical exam to rule out other illnesses that could be causing cognitive issues. As part of this process, your doctor will ask about your diet and other habits, such as alcohol or drug use, and review your medications.
Cognitive screening tests are an important tool in diagnosing Alzheimer’s and other forms of dementia. These tests can range from short to intensive, and look at areas like memory, thinking, and problem solving. It’s common for your doctor to ask questions that help screen for a mood disorder, like depression, at the same time.
Finally, your doctor may use lumbar puncture and cerebrospinal fluid tests to look for Alzheimer's brain markers like beta-amyloid and tau. A couple of these tests have been approved for use in the United States.
There is currently no definitive test for vascular dementia and no way to diagnose it conclusively, except through autopsy after death. Doctors make a judgment call on the basis of information the patient provides, a medical history of stroke or other cardiovascular disorders, and a battery of tests, including brain imaging.
To gauge the health of your heart and blood vessels, doctors measure:
Blood pressure
Cholesterol
Blood sugar
To evaluate the overall health of your neurological system, doctors check:
Mental status and cognitive function (this is the most important factor when evaluating for dementia)
Reflexes
Muscle tone and strength, comparing one side of the body to the other
Ability to get up from a chair and walk across the room
Sense of touch and sight
Coordination
Balance
To look for visible abnormalities in the brain, doctors might recommend one of the following imaging procedures:
Computerized Tomography (CT) Scan By creating cross-sectional X-ray images of the brain, a CT scan reveals the brain’s structure, signs of atrophy (shrinkage), and evidence of strokes, ministrokes, blood vessel changes, or tumors.
Magnetic Resonance Imaging (MRI) Through a combination of radio waves and a strong magnetic field, an MRI can deliver even more detailed images of the brain than a CT scan.
To assess cognitive skills, doctors use neuropsychological tests to gauge the patient’s ability to:
Comprehend language, speak, and write
Work with numbers
Learn and recall information (this may be less challenging for people with vascular dementia than patients with Alzheimer’s)
Create a strategy to solve a problem (this may be especially difficult for people with vascular dementia)
Come up with appropriate responses to hypothetical situations
While a main focus of diagnosing vascular dementia has been distinguishing it from Alzheimer’s disease, many people actually have signs of both conditions, according to Mayo Clinic.
A Lewy body dementia diagnosis is especially complicated because its symptoms may be similar to those of Alzheimer’s, Parkinson’s disease, or a psychiatric illness.
To distinguish Lewy body dementia from other brain disorders, researchers are studying a number of methods, including the use of lumbar puncture to measure proteins in cerebrospinal fluid.
The core symptoms of Lewy body dementia include the following, with not every person showing every symptom:
Dementia, or advanced cognitive impairment
Fluctuating, unpredictable alertness or ability to think
Visual hallucinations
Parkinsonian symptoms, such as physical rigidity
REM sleep behavior disorder, in which people act out their dreams while asleep
The following symptoms may also indicate Lewy body dementia:
Problems with involuntary functions, such as unstable blood pressure or incontinence (loss of bladder or bowel control)
Falls or fainting
Loss of sense of smell
Doctors may also use other tests to help support a diagnosis of Lewy body dementia. These include:
Nuclear imaging tests such as SPECT (single-photon emission computerized tomography) and PET (positron emission tomography)
Tests that assess blood vessels in the heart to measure nerve function
Sleep studies that evaluate brain waves
To rule out other conditions with symptoms resembling those of Lewy body dementia, such as Parkinson’s disease, stroke, or a brain tumor, doctors may conduct neurological and physical exams that assess:
Reflexes
Strength
Walking
Muscle tone
Eye movements
Balance
Sense of touch
Additional tests to rule out other types of dementia might include:
MRI, PET, or CT Scan These may identify brain changes unique to Lewy body dementia and rule out the possibility of a tumor, stroke, or other causes of cognitive impairment.
Cognition and Memory Test An extended version of this test can reveal disordered thinking characteristic of Lewy body dementia
Frontotemporal dementia can be particularly difficult to diagnose in its early stages, as its symptoms resemble those of other forms of dementia.
What’s more, changes in behavior caused by frontotemporal dementia may lead observers to suspect a mood disorder like depression. Sometimes, behavior that is considered inappropriate leads to conflict with family and friends long before any diagnosis.
As with other forms of dementia, researchers are working on new diagnostic methods involving biomarkers and genetic changes.
To help diagnose frontotemporal dementia, your doctor may order or administer the following tests:
Blood Tests Certain tests may help rule out liver or kidney disease.
Sleep Study Sometimes, sleep apnea causes changes in thinking or behavior similar to those seen in frontotemporal dementia.
Neuropsychological Testing Tests that look at thinking, problem solving, and memory can help distinguish frontotemporal dementia from other dementia types.
Brain Imaging Magnetic resonance imaging (MRI) can show changes in the size or shape of your brain’s frontal or temporal lobe, as well as issues like a clot or tumor.
The first step in a dementia diagnosis is to talk to your doctor about your concerns, after which you may take a screening test. If your results indicate cognitive problems, you may need to undergo a series of tests to identify the type of dementia you have — often a lengthy and difficult process.
