We rely on memory to get and keep meaning from life. That may be why even small lapses, like misplacing car keys or forgetting a doctor’s appointment, can lead to anxiety about our brain health. In fact, about half of U.S. adults between ages 50 to 64 worry they will develop dementia, along with the severe memory loss and cognitive confusion that come with it, according to a recent national poll.
For now, though, the fear of developing dementia outpaces the number of diagnoses. Overall, about 14% of U.S. men and women older than 71 have some form of dementia. But those numbers will likely increase as the baby boomers (those born between 1946 and 1964) grow older.
Dementia is not part of the normal aging process; instead, it’s a symptom of an underlying brain disease. Alzheimer’s disease causes between 60 and 80% of all dementia cases in this country, meaning that about one in 10 Americans ages 65 or older currently lives with it. The remaining cases could be caused by more than a dozen other neurological conditions, including four common types of dementia: vascular, Lewy body, frontotemporal, and mixed.
“Alzheimer’s is a heart-breaking disease,” says Yale Medicine’s Christopher van Dyck, MD, a geriatric psychiatrist who conducts research in the Alzheimer’s Disease Research Unit and provides clinical care in the Dorothy Adler Geriatric Assessment Center.
Those with Alzheimer’s disease and other memory disorders may show frustration at being unable to express a deep, inner confusion of jumbled thoughts. They may not know how they arrived somewhere, or how to get back home. As the disease progresses, their loved ones might turn into unrecognizable strangers. A person will reach a point where he or she is incapable of communicating coherently.
Dr. van Dyck witnessed both of his maternal grandparents suffer through Alzheimer’s disease during visits home as a medical school student. That experience, combined with an interest in neuroscience, led him to study the disease and specialize in treating patients with it. Dr. van Dyck provided answers to some frequently asked questions about dementia. The interview has been edited for length and clarity.
What is dementia?
Dementia is a decline in cognitive function that impairs daily living, to a point where a person is no longer independent. But it’s important to note that dementia is a syndrome, or a group of symptoms. Alzheimer’s is a disease and the leading cause of dementia. It’s similar to asking what knee pain is. Knee pain is a symptom that can be caused by different things, like osteoarthritis.
Other leading types of dementia are frontotemporal dementia, Lewy body dementia, and vascular dementia, and there are many others that are much less common. Doctors are able to tell with general probability what is causing the dementia, but a definitive answer is possible only with a brain autopsy.
Why does dementia occur?
Alzheimer’s is far and away the leading cause—it accounts for about two-thirds of all late-onset dementia [which generally affects people after the age of 65]. Other disorders and diseases account for the rest. And why Alzheimer’s disease occurs is an unending and, perhaps, philosophical question. For example, you could ask, “What are the changes in the brain that precede and are associated with the onset of symptoms?” But then you would also have to ask why those occur. And so on. You could also ask: "What predisposes certain people to get Alzheimer’s disease?" The greatest risk factor is age. Among U.S. men and women ages 65 to 75, about 3% have Alzheimer’s; for ages 75 to 85, between 10 to 15% live with the disease; and for those older than 85, approximately 35% have it.
So, why is age a risk factor? We don’t fully know—and that’s a big area of current research. The second most important risk factor is family history and genetics: The major genetic risk factor is called apolipoprotein E4 [APOE4], which might account for up to 40% of the risk. But why is APOE4 a risk factor? Again, we don’t fully know. A nonhereditary risk factor is previous head injuries. And, of course, there is much ongoing research about lifestyle, including diet and exercise. So, there’s not a clear-cut answer on why dementia occurs.
How does dementia affect the brain?
It depends on the cause of dementia. With Alzheimer’s, it affects the brain by causing neurodegeneration—or damage and death to specific brain cells in specific parts of the brain—that then spreads over time. We also see a loss of synapses [or connections] in the brain that occurs out of proportion to the death of those brain cells. The leading view of Alzheimer’s is that it’s related to the formation of amyloid protein in the brain, but that is disputed. There are other changes happening, such as tau protein deposits, called tau tangles. Even if you believe the amyloid protein hypothesis, then you can ask why do the protein buildups occur [in the first place]? We don’t fully know.
How is dementia diagnosed?
Dementia—as the syndrome—is diagnosed by a clinical assessment of the person to see if he or she has a decline in cognitive ability and activities of daily living, sufficient to have a loss of independence. This is done through cognitive testing and interviews with the family. They might ask how the person manages with driving a car or getting dressed. Once you establish that a person has dementia or a lower-level cognitive disorder, then you try to determine the cause through a medical evaluation, and that includes physical and neurological examinations, as well as blood tests and brain imaging, which would be MRI or PET scans.
Those tests largely rule out other medical causes of dementia. However, for “ruling in” Alzheimer’s disease, we look at specialized biomarker studies, such as an amyloid PET scan (to look for amyloid deposits in the brain) or a lumbar puncture (to look for alterations in levels of such fluid proteins as amyloid and tau. Amyloid PET scans are not reimbursed by insurance and probably won’t be until we have a specific and significant treatment to offer based on the results. Blood tests for Alzheimer’s disease are making great progress, though, and may be available—at least as screening tests—in a few years.
What kind of doctor treats dementia?
In general, dementia and Alzheimer’s could be initially diagnosed by a primary care doctor, who is able to take the time for a full evaluation. There are specialists, such as neurologists, geriatric psychiatrists, or geriatric internists, who can provide more definitive diagnoses and develop detailed treatment plans for patients. For the diagnosis of dementia, neuropsychologists also play a key role, though they are not usually involved in the actual treatment of the disease. If a patient has a confusing presentation of symptoms, a neuropsychologist can be very useful in establishing that a cognitive abnormality exists and in distinguishing between the different types of disease.
How should one approach care for a dementia patient?
That’s a very broad question that really depends on the cause of the dementia, the stage of dementia, and the individual circumstances of the person and his or her family. Not everyone is the same. In Alzheimer’s disease, once a diagnosis is made, the early care is usually focused on starting medications (cholinesterase inhibitors, like donepezil) to address symptoms, plus antidepressants for depression, if necessary. The early care is also focused on helping the family set expectations for the future so they can address any legal and financial planning concerns. Driving safety may also need to be formally evaluated.
As the disease progresses, the care may involve more assistance with activities of daily living, such as eating and dressing. Home care, which has the added benefit of alleviating burden on the spouse and other family members, can be helpful at this stage. We may consider other medications such as memantine [that may help with memory and learning], which may be appropriate in the moderate stages of disease, or other psychotropic medications for specific behaviors, such as agitation. In the later stages of the disease, all of the above continues, but the care may also be focused on considering alternative living arrangements, such as assisted living, a memory care unit, nursing home placement, or hospice care. But, with appropriate services in place, many people with Alzheimer’s disease are able to live at home to the very end.
Can dementia lead to death?
This is a bit of a semantic question. Dementia doesn’t cause death. But the life expectancy of a person with Alzheimer’s is about 10 years on average, from the very earliest symptoms to death, and it does vary. So, it shortens life expectancy, but the immediate causes are likely to be things like pneumonia, dehydration, or falls. Neurodegenerative causes of dementia—like Alzheimer’s disease—shorten life expectancy more than vascular diseases that cause dementia—individuals with vascular dementia can be fairly stable over time.
Can dementia be prevented?
Again, it depends on the cause. If we are talking about Alzheimer’s disease, we don’t currently have a program or intervention for preventing it. You can prevent head injuries, and maybe reduce some risk. But you cannot prevent the biggest risk factor—aging. You cannot alter family history and genetics—at least, not yet. One of the big areas of research interest is lifestyle choices, like eating well and exercising. Aerobic exercise and Mediterranean diets, with an emphasis on fruits and vegetables and limited carbohydrates, are associated with a lower risk. But we don’t have studies that prove this. However, we are currently conducting randomized controlled trials on the effects of both aerobic exercise (EXERT study) and specialized diets. I don’t think we expect these things to prevent dementia, but they could help to lower the risk. There are also ongoing therapeutic trials that attempt to lower the risk of Alzheimer’s by, for example, lowering brain amyloid levels. So far, nothing has been proven to work, but this is an area of intense research, and I remain very hopeful.