Some cognitive decline is normal with age. However, when people experience a decrease in particular skills, like thinking, reasoning, remembering, and ambulation, severe enough to interfere with daily living, they may be on the road to developing the syndrome of Dementia - the cluster of symptoms brought on by one or more neurological diseases or disorders that negatively affect the brain. Dementia symptoms can range from mild to severe and, by definition, will likely worsen with time.
There are several different types of Dementia brain pathologies. The four most common are:
Alzheimer's Disease-related Dementia. This type of Dementia is common among older adults. Alzheimer's disease is marked by a buildup of proteins (sticky amyloid plaques) and neuron destruction (tau tangles) that affect cognitive functions. How these changes come about is not entirely known, but genetic, lifestyle, and environmental factors likely play a role. Dementia symptoms such as short-term memory loss and an inability to reason are early hallmarks of this disease.
Vascular Dementia. This type of Dementia is linked to various conditions, such as cardiovascular and lung diseases, that affect oxygen and blood flow in the brain. These Dementia symptoms can appear gradually or occur suddenly. Strokes increase the risk for vascular Dementia, but not everyone who has a stroke develops Dementia.
Lewy Body Dementia (LBD). This grouping of Dementia syndromes is seen with abnormal deposits of the protein alpha-synuclein in the brain. Also known as Lewy bodies, these deposits affect chemicals in the brain that cause brain changes, leading to difficulty thinking, sleep and visual disturbances, and problems with movement, behavior, and mood.
Frontotemporal Dementia (FTD). This type of Dementia is marked by damage to neurons in the frontal and temporal lobes of the brain. Symptoms include unusual behaviors, trouble communicating with others, emotional issues, difficulty finding words, walking, and performing tasks at work and home.
Why is Differentiating Dementias Important?
Making the proper diagnosis and pinpointing the type of Dementia is the first step toward managing and treating it appropriately, says Vijaya B. Kolachalama, PhD, associate professor of medicine at Boston University and an author of a 2024 study in Nature on using artificial intelligence to differentiate the diagnoses of Dementia. "It's critically important to have the right diagnosis because some patients may have reversible conditions," he says. "For example, if there is a vitamin deficiency causing Dementia, then giving the patient supplements can help. If their Dementia is not reversible, you can do certain things to make sure the patient is managed well."
How is Dementia Diagnosed?
When a patient exhibits cognitive difficulties, healthcare providers perform a number of Dementia screenings to try to determine what the cause might be. Tests include a physical exam and lab work to check levels of various chemicals, hormones, and vitamins in the person's blood and urine. Reviewing the person's family and medical history can help provide other vital clues, including what medications the person is on (some can cause memory issues). If there are other factors at play, such as heavy alcohol use or a recent brain injury, that may be causing cognitive symptoms.
Other tests likely to be used include cognitive and neurological tests to evaluate a person's memory, problem-solving skills, and reasoning abilities. Brain scans such as magnetic resonance imaging (MRI) and computed tomography (CT) may also help identify if there are structural changes in the brain tied to cognition.
When patients exhibit behavioral or mood changes, they may also undergo psychiatric evaluations to determine whether they are depressed or have other mental health conditions that could be contributing to the symptoms.
Types of Diagnostic Tools to Differentiate Dementias
It isn't easy to differentiate Dementias from each other. A person can have more than one type at the same time. Still, researchers have developed many tools to help providers determine what changes are occurring in the brain and evaluate the kind of cognitive decline that is apparent, says John O'Brien, FMedSci, professor of Old Age Psychiatry and NIHR emeritus senior investigator in the Department of Psychiatry at the University of Cambridge School of Clinical Medicine in England.
Once reversible causes have been ruled out, further testing may be necessary. Specifically, O'Brien recommends a verbal episodic memory test for Alzheimer's disease, which might include reading the person a list of words or a short story and then asking them to recall the information immediately and again after a delay.
O'Brien also says that providers should use the international consensus criteria established for Dementia with Lewy bodies and frontotemporal Dementia as a checklist. If the patient has several symptoms on the list, it can suggest they have that type.
The international consensus criteria of Dementia with Lewy bodies, as an example, include Dementia examinations to look for four clinical features: pronounced variations in the person's attention and mental alertness, visual hallucinations, signs of Rapid Eye Movement (REM) sleep behavior disorder, and movement issues such as tremors and rigidity.
According to the same international consensus body, the behavioral variant of Frontotemporal Dementia (FTD) is a possibility with at least three of the following findings: exhibiting socially inappropriate behavior, apathy, lack of empathy, compulsive behaviors, changes in taste and diet, and functional decline in managing tasks. Imaging such as MRI, CT, and positron emission tomography (PET) or single-photon emission computed tomography (SPECT) of the brain's frontal lobe should also be used to determine whether someone has FTD, O'Brien says.
Researchers hope to find even better ways of diagnosing FTD earlier and distinguish it from other Dementia types better. One area under scrutiny is biomarkers - specific proteins that may be found in higher amounts in blood or cerebrospinal fluid in patients with FTD.
A handful of biomarker blood tests are available today, and many are being studied for their role in Dementia diagnosis. Sensitive blood tests that predict the level of beta-amyloid in the patient's brain, for instance, are available to doctors. The results could be a clue to the type of Dementia the person has, but these blood tests are not used alone for a diagnosis.
Genetic testing may also play a role in helping to inform a diagnosis of FTD, which has been tied to several genetic mutations and can run in families.
Brain imaging tests such as CT, MRI, and PET can help determine whether vascular or other issues cause the Dementia symptoms a person is exhibiting, O'Brien says. These pictures of the brain uncover damage, such as tumors, stroke, shrinkage of brain areas, or abnormal deposits or destruction (sticky plaques or neuronal tangles).
Other diagnostic tools are in development and hold promise for differentiating Dementias. For example, Kolachalama and colleagues at Boston University are developing a tool that uses artificial intelligence (AI) to help distinguish the causes of a person's Dementia. The differential AI Dementia diagnosis model uses several data types, including demographics, health history, neurological tests, physical exams, and MRI scans. Kolachalama says their AI tool must still be tested in clinical settings. Still, early indications show that when combined with these data sets, the tool performs better than neurologists' assessments alone.
The author's opinions are not necessarily those of the Dementia Society, Inc. We do not endorse or guarantee products, comments, suggestions, links, or other forms of the content contained within blog posts that have been provided to us with permission, paid or otherwise. Dementia Society does not provide medical advice. Please consult your doctor.
Contributing author: Beth W. Orenstein
Beth W. Orenstein is a freelance medical writer. A magna cum laude graduate of Tufts University, Orenstein has written for HealthDay, EverydayHealth, and the National Psoriasis Foundation and is a regular contributor to American Legion Magazine's Living Well and Radiology Today.
Kommentare