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Dementia 101: Not all dementia is Alzheimer's disease. Knowing the difference affects planning, management, and prognosis. Our primer breaks down the four most common types, as well as four not-so common ones.

Cohen, Marisa

doi: 10.1097/01.NNN.0000475911.94610.63
Features: Dementia

Not all dementia is Alzheimer's disease. Knowing the difference affects planning, management, and prognosis. Our primer explains the differences.

WEB EXTRA: For more information about habits that are good for your brain, visit http://bit.ly/NN-brain-habits. For strategies designed to lighten the load for caregivers of people with any type of dementia, visit http://bit.ly/NN-Care.

Forgetting a name, misplacing keys, becoming momentarily confused—these can be byproducts of normal aging or the early symptoms of dementia. If it's normal aging, the names will be recalled, the keys will be found, and the confusion will lift. But for the 14 percent of Americans over age 70 who have some type of dementia, those names may never come back, and the memory loss and confusion become so debilitating that daily tasks like driving, shopping, and paying bills become increasingly difficult.

As Americans continue to live longer, dementia is poised to become the biggest health challenge of the next few decades. The US Centers for Disease Control and Prevention (CDC) expects the number of people living with Alzheimer's disease, the leading cause of dementia, to more than double from 5 million to 14 million by 2050. Still, about half of all cases of Alzheimer's—not to mention other types of debilitating brain disease, including non-Alzheimer's dementias—go undiagnosed, says John C. Morris, MD, FAAN, director of the Knight Alzheimer's Disease Research Center at Washington University in St. Louis.

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IT'S BETTER TO KNOW

Because no cure exists for most types of dementia, many patients and their families hesitate to have their suspicions confirmed. But experts recommend speaking to a neurologist as soon as memory or behavior problems occur. “I've found that people deal with disease better if they have more information about it,” says Paul Barton Rosenberg, MD, associate director of the Memory and Alzheimer's Treatment Center at Johns Hopkins University. “Getting an accurate prognosis, which is different for different types of dementia, helps patients and caregivers plan better and allays their anxiety.”

And the earlier people get a diagnosis, the more likely they are to be eligible for research trials, Dr. Rosenberg says. (For more information about enrolling in trials, go to http://alz.org and look for the Alzheimer's Association TrialMatch tool, or see “A Noble Idea”.)

Follow this primer to understand the differences between Alzheimer's disease and other dementias, and to learn ways to manage the symptoms.

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Alzheimer's Disease

CAUSES: The brain changes characteristic of Alzheimer's disease, which affects between 60 and 80 percent of all people with dementia, usually start years before any symptoms appear, when protein deposits start to form in the brain. Plaques, which are made up of a protein called beta-amyloid, clog the spaces between nerve cells; a little later in the process, tangles—twisted fibers of the tau protein—accumulate inside the cells. Both interfere with the ability of neurons to send and receive information and eventually cause brain cells to die. “Clinical problems typically begin with hippocampus-related short-term memory and learning, but gradually involve temporal, frontal, and occipital lobe functions, including language, executive function, and vision,” says Dena Dubal, MD, PhD, an assistant professor of neurology and an endowed chair of aging and neurodegenerative disease at the University of California, San Francisco.

SYMPTOMS: The most noticeable early symptom is short-term memory loss. People may remember childhood stories but will forget conversations that happened five minutes earlier. They may also have difficulty retaining new information, asking the same questions repeatedly. Depression and apathy are also common at this point, as is confusion about dates and times. As the disease progresses, people start using poor judgment, have trouble communicating, or are confused and disoriented. By the end, people have trouble speaking, following a conversation, swallowing, and walking.

CURRENT TREATMENTS: The disease cannot be stopped or reversed, but the US Food and Drug Administration (FDA) has approved two types of medications to treat symptoms: acetylcholinesterase inhibitors, which inhibit the breakdown of acetylcholine, a brain chemical involved in learning and memory; and memantine, which blocks the activity of the neurotransmitter glutamate, which at high levels can destroy nerve cells. Acetylcholinesterase inhibitors are often prescribed in the earlier stages of the disease and include donepezil (Aricept), galantamine (Razadyne), and rivastigmine (Exelon). Memantine (Namenda) is used more in the later stages and may help with language, attention, and the ability to perform simple tasks. However, these drugs work for only about half the people who take them, and their effects last only six to 12 months.

NEW TREATMENTS: Eli Lilly's phase 3 trials of a drug called solanezumab show that this antibody may slow the progress of very mild Alzheimer's dementia by binding the beta-amyloid protein and helping the body flush it out before it can develop into sticky plaque, although more research is needed. Trials are also underway with BACE inhibitors, which block beta-secretase 1, an enzyme that contributes to the production of beta-amyloid, and with other antibodies designed to clear accumulated toxic proteins from the brain.

ONGOING RESEARCH: Breakthroughs in genetics, biomarkers, and brain imaging should soon make it easier to diagnose conditions like Alzheimer's in the earliest stages, even before symptoms begin, when these drugs may be most effective. Scientists are looking at ways to detect the earliest hints of Alzheimer's by measuring the level of tau and beta-amyloid proteins in the blood, urine, cerebrospinal fluid, and even in the lens and retina of the eye. They are also examining how positron emission tomography (PET) scans might be used to analyze brain volume and glucose levels to detect early changes. Meanwhile, geneticists are trying to identify genes that indicate a predisposition to Alzheimer's.

AGE OF FIRST SYMPTOMS: Although changes in the brain can begin decades earlier, in the stage known as pre-clinical Alzheimer's disease, the majority of people don't exhibit symptoms until their mid-60s or later. “A small subgroup of people, less than 1 percent of all Alzheimer's patients, inherit a genetic mutation that causes the disease. For them, the disease can start in their 50s, 40s, 30s, and, rarely, in their 20s,” says Dr. Morris. By age 85, there is almost a one-in-three chance that any given adult will have Alzheimer's, according to research from the Rush Institute for Healthy Aging.

PROGNOSIS: The average person with Alzheimer's disease lives about eight years past his or her diagnosis. That time can be shortened to a few years or lengthened to as many as 20, depending on how old the person is at diagnosis and other health conditions.

ASSOCIATION: Alzheimer's Association (http://alz.org)

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Lewy Body Dementia

CAUSE: Described by Dr. Rosenberg as “a cross between Alzheimer's disease and Parkinson's disease,” this type of dementia occurs when protein deposits called Lewy bodies accumulate in nerve cells in the areas of the brain responsible for memory, motor control, and thinking. (When the Lewy bodies attack the brainstem first, causing stiffness, rigid muscles, and difficulty walking, the condition is diagnosed as Parkinson's disease.) “As the disease progresses and the protein bodies spread across the brain, people with Lewy body dementia begin to have Parkinsonian symptoms. And the majority of people with Parkinson's disease develop dementia,” Dr. Dubal explains.

SYMPTOMS: Visual hallucinations are common in people with Lewy body dementia. They may start talking to someone who isn't there or see specific images of animals or objects. Their moods and awareness may fluctuate rapidly. “A patient may seem coherent one moment and then be staring into space the next,” says Dr. Dubal. People may also have sleep disturbances such as acting out dreams at night, says Jennifer Molano, MD, an assistant professor of neurology at the University of Cincinnati Academic Health Center. As the disease progresses, the physical symptoms of Parkinson's, such as rigid muscles and stiffness, can appear.

TREATMENT: No medications have been developed specifically for Lewy body dementia, but neurologists often treat memory problems with the same acetylcholinesterase inhibitors used for Alzheimer's. They treat movement difficulties with levodopa, a standard treatment for Parkinson's disease. For people with severe, debilitating hallucinations, neurologists may prescribe antipsychotics—with caution. Antipsychotics can make cognitive symptoms worse, cause heavy sedation, or increase Parkinson's-like symptoms. In addition, the FDA has warned that both typical and atypical antipsychotics increase the risk of death in elderly people with dementia. Typical antipsychotics, including chlorpromazine (Thorazine) and haloperidol (Haldol), are not recommended for people with Lewy body dementia. Newer atypical antipsychotics, such as quetiapine (Seroquel) and clozapine (Clozaril), may be prescribed at low doses, but should be monitored very closely.

AGE OF FIRST SYMPTOMS: Symptoms usually appear after age 60; the disease is more common in men than in women.

PROGNOSIS: Survival is about eight years after diagnosis.

ASSOCIATION: Lewy Body Dementia Association (http://lbda.org)

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Vascular Dementias

CAUSE: Vascular dementias include a number of disorders in which cerebrovascular disease prevents proper blood flow to the brain, depriving brain cells of oxygen and nutrients, which lead to cognitive decline. Damage to blood vessels can occur as a result of a major stroke, a series of tiny strokes, or chronic untreated high blood pressure.

SYMPTOMS: Because vascular dementias are numerous and complex, symptoms vary. If dementia is caused by a major stroke, the person may be confused, disoriented, and have trouble speaking or understanding others. If dementia is due to a series of small strokes, the symptoms may include impaired judgment, sudden bursts of laughter or tears, lack of focus, difficulty finding words, absentmindedness, tremors, muscle weakness, and balance problems. As with Alzheimer's disease, people have memory loss, but visual cues may jog their memory.

TREATMENT: No drugs are approved by the FDA to treat vascular dementias, but a meta-analysis published in The Lancet Neurology in 2007 found that Alzheimer's drugs may benefit people with mild to moderate cases. The main goal is to prevent further damage to the brain by reducing the risk of a future stroke. Stroke survivors are encouraged to quit smoking and drinking and to manage their high blood pressure, cholesterol, and diabetes with medications and lifestyle changes.

AGE OF FIRST SYMPTOMS: The age at which symptoms appear varies, but vascular dementia is more common in older adults.

PROGNOSIS: Data suggest that someone whose dementia is caused by a stroke will survive about three years after the stroke, according to the Alzheimer's Association.

ASSOCIATIONS: American Stroke Association (http://strokeassociation.org); National Stroke Association (http://stroke.org)

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Frontotemporal Dementia

CAUSES: Frontotemporal dementia is an umbrella term for a group of conditions, including behavioral-variant frontotemporal dementia and certain types of primary-progressive aphasia that involve difficulty speaking and understanding language. Two different proteins, tau and TDP-43, attack the brain's frontal and temporal lobes, the sections behind the forehead and the ears that affect behavior, language, and motor function, causing progressive loss of nerve cells.

SYMPTOMS: The most notable symptom of behavioral-variant frontotemporal dementia is a change in behavior. People may suddenly start behaving aggressively, using inappropriate language, and even acting out sexually. They may also have trouble forming sentences or speaking coherently. Memory loss isn't a symptom until after the disease progresses.

TREATMENT: No treatment is currently available, but neurologists sometimes prescribe antidepressants or antipsychotics to help manage irritability, aggression, and mood changes.

AGE OF FIRST SYMPTOMS: For people without a family history of early-onset Alzheimer's disease who develop dementia before age 65, frontotemporal dementia may be responsible as often as Alzheimer's, says Dr. Morris. It commonly appears between ages 45 and 65, but it can develop earlier or later.

PROGNOSIS: Typically, people live seven to 13 years past diagnosis.

ASSOCIATION: The Association for Frontotemporal Degeneration (http://theaftd.org)

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4 Less Common Types of Dementia

Some rare disorders can affect parts of the brain related to memory and reasoning.

NORMAL PRESSURE HYDROCEPHALUS: Occurring mainly in people in their 60s and 70s, normal pressure hydrocephalus is caused by a buildup of cerebrospinal fluid in the ventricles of the brain. The pressure the fluid puts on the brain can affect balance and bladder control, as well as thinking, memory, and reasoning. Some of the symptoms may be alleviated by installing a brain shunt.

HUNTINGTON'S DISEASE: About 30,000 Americans have this progressive, inherited brain disorder. Symptoms usually develop between ages 30 and 50, but they can appear much earlier or later. While the primary symptom of Huntington's disease is involuntary movements, it also causes a decline in concentration, reasoning, memory, and mood.

CREUTZFELDT-JAKOB DISEASE: A very rare brain disorder that strikes only about 300 Americans each year, Creutzfeldt-Jakob is a fast-moving, fatal disease caused by an infectious misfolded prion protein in the brain. It can be inherited, but in most cases it is sporadic, meaning it has no known cause. During the mad cow disease scare in Great Britain in the 1990s, several cases of Creutzfeldt-Jakob disease were linked to the consumption of meat from animals infected with prion disease; however, US Department of Agriculture restrictions have virtually eliminated that risk in this country.

WERNICKE-KORSAKOFF SYNDROME: A degenerative brain disease caused by a deficiency of thiamine (vitamin B1), Wernicke-Korsakoff syndrome can be brought on by alcoholism, anorexia or other severe weight loss, untreated AIDS, kidney dialysis, and chronic infection. Symptoms include memory loss, vision problems, lack of concentration, confabulation (unintentionally making up stories to fill in memory gaps), and disorientation.

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5 Contributors to Cognitive Decline

Some conditions may raise your risk for dementia. Your best bet is to get them under control.

1 OBSTRUCTIVE SLEEP APNEA: Around 25 million Americans, primarily older and overweight adults, have obstructive sleep apnea, in which air passages become blocked during sleep and interrupt breathing. Some people stop breathing hundreds of times a night. Most people snore loudly and wake up foggy-headed in the morning from a lack of deep sleep. A 2013 study in Neurology by researchers at Washington University School of Medicine in St. Louis found that older adults with sleep apnea (who had an average age of 75) had a greater risk of developing dementia.

How to treat: If you suspect sleep apnea, talk to your doctor about getting a referral to a sleep specialist for further evaluation and a possible sleep study. Treatment options include wearing a continuous positive airway pressure machine (a mask that blows air through the mouth and nose) at night, an oral appliance that keeps the airway open, losing weight (since extra tissue in the back of the throat related to obesity can block the flow of air into the lungs during sleep), or even surgery, which typically removes the uvula.

2 DEPRESSION: Research has found a link between late-life depression and the risk of both Alzheimer's disease and vascular dementia, but it's tricky to know which comes first, says Dr. Rosenberg of the Johns Hopkins Memory and Alzheimer's Treatment Center, since dementia also causes depression. “Older people who are depressed sometimes think they have Alzheimer's disease, but their worries are often far worse than their actual cognitive impairment,” he says. People who are severely depressed may find it difficult to focus, making them feel like they might have dementia, he adds.

How to treat: Ask your doctor for a referral to a therapist for talk therapy or to a psychiatrist, who can prescribe antidepressants. The class of antidepressants known as selective serotonin reuptake inhibitors are the least likely to interact badly with Alzheimer's disease drugs, according to the Alzheimer's Association.

3 DIABETES: For many years, scientists have seen a link between type 2 diabetes and dementia risk. But a recent study from Kaiser Permanente in California found that adults with type 1 diabetes, which is typically diagnosed at a younger age and isn't usually associated with obesity, were 93 percent more likely to develop dementia than those without the disease. These findings may point to a deeper connection between insulin and brain health.

How to treat: If you have diabetes, be vigilant about testing your blood sugar and cholesterol levels, maintain a healthy diet, and try to exercise for 30 minutes most days.

4 HEAD TRAUMA: Older people who have experienced a head injury from a car accident or a bad fall, for example, have more than double the risk of developing Alzheimer's compared with those who have no history of head injury, according to research from Duke University Medical Center. Plus, evidence suggests that sustaining repeated blows to the head from high-contact sports such as football and boxing may lead to a condition called chronic traumatic encephalopathy, in which progressive damage to nerve cells causes Alzheimer's-like symptoms, including short-term memory loss, difficulty thinking, and emotional instability.

How to treat: Prevent falls, the leading cause of traumatic brain injury in seniors, by making your home as safe as possible. Remove small rugs that can be tripped over easily, install grab bars in your shower and next to your toilet and handrails on all staircases, make sure your eyeglass prescription is up-to-date, and consider learning tai chi, which can help improve balance. If you do fall, have someone take you to a doctor or call 911 right away, especially if you experience headache, dizziness, slurred speech, nausea, or confusion.

5 ALCOHOLISM: Chronic alcoholism is one of the leading causes of Wernicke-Korsakoff syndrome (see “4 Less Common Types of Dementia” on page 47), which affects short-term memory. “The good thing is that if you stop drinking, your symptoms can stabilize,” says Dr. Rosenberg.

How to treat: If you're having trouble giving up drinking on your own, find your nearest Alcoholics Anonymous meeting at http://AA.org, or call the US Department of Health and Human Services Substance Abuse and Mental Health Services Administration for referral to a local treatment program (800-662-HELP).

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Rule Out Reversible Conditions

One more reason to talk to your doctor about memory problems: You might get good news.

An estimated 9 percent of patients presenting with dementia symptoms actually have reversible conditions, including thyroid problems, excess fluid in the brain, vitamin deficiencies (particularly vitamin B12), and, most commonly, side effects from medications.

“Many of the medications older people take, including tranquilizers, pills for bladder incontinence, sleeping pills, even over-the-counter drugs like antihistamines and pain relievers, can cause confusion,” says Dr. Rosenberg.

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More Than One Dementia

As researchers look more closely at the brains of people who've died from dementia, they're discovering that one, two, or even three types of dementia may occur at the same time. A large ongoing study at Rush University Medical Center called the Memory and Aging Project is finding that more than half of patients with Alzheimer's disease also had a second type of dementia—most commonly vascular dementia, but also sometimes Lewy body dementia. Because the vast majority of these people are diagnosed first with Alzheimer's, the treatment for mixed dementia remains primarily the drugs rivastigmine (Exelon) and galantamine (Razadyne). But the results of these studies emphasize the importance of maintaining good vascular health, regardless of the type of dementia.

© 2015 American Academy of Neurology