Alzheimer's disease is the most common form of dementia, accounting for 60 to 80% of all cases. Dementia is a broad term for neurological conditions that involve some form of serious mental impairment, such as memory loss, confusion, and/or personality changes. Around 20% of dementias can be cured or at least treated, but many dementias that become progressively worse over time are incurable, as is currently the case with Alzheimer's. As such, the outcome for Alzheimer's disease and many forms of dementia is ultimately death. Note: Alzheimer's disease (AD) is also known as Senile Dementia of the Alzheimer Type (SDAT) or simply Alzheimer's.
What is Alzheimer's Disease?
Although early-onset Alzheimer's exists, Alzheimer's is a degenerative brain disease that usually affects the elderly. In a patient diagnosed with Alzheimer's, the brain develops plaques and tangles and loses neurons. Tangles consist of a tau protein, and the plaques result from another protein—amyloid beta—that folds in upon itself and forms long fibers that accumulate.
During Alzheimer's, the brain is disrupted from its normal function, causing dementia. A patient's memory, mental clarity, and at times even language capabilities become increasingly impaired over time. The disease produces physical changes in the brain, with some areas shrinking and others widening. When parts of the brain shrink or widen, the normal connections inside are broken, disrupting electrical signals in the brain.
For an interactive tour of the brain with Alzheimer's, see here.
What is Dementia?
Contrary to popular belief, dementia is not a specific disease, but rather a term that refers to symptoms of mental and communicative impairment found in a variety of brain conditions and diseases, including Alzheimer's. About 20% of dementia can be reversed, with the rest being irreversible and tending to worsen with time.
Though dementia and Alzheimer's are more common among the elderly, they are not a normal part of aging. Some cognitive impairment (e.g., minor forgetfulness) is to be expected with old age, but dementia is often the extreme end of impairment that decreases quality of life. In most all cases, older patients with dementia will eventually need long-term, full-time care.
Aging is intricately tied to symptoms of dementia and the development of Alzheimer's disease. A person's chance of developing Alzheimer's doubles every five years from age 65 to age 85. Typical symptoms of dementia that are not necessarily tied to Alzheimer's also tend to develop after age 65. The percentage of elderly suffering from some form of dementia increases with age, with 2% of those aged 65-69, 5% of those aged 75-79, and over 20% of those aged 85-90 experiencing symptoms. One third of those 90 and older experience moderate to severe dementia.
Dementia's associated mental and physical decline can be very slow. Most patients with Alzheimer's disease will live with the disease for 8-12 years. A more rapidly progressing form of Alzheimer's known as early-onset Alzheimer's can also affect adults in their late 30s and early 40s. In general, Alzheimer's is thought to be hereditary, but it may skip generations in a family.
Dementia can be caused by a variety of illnesses, some very treatable, others—like Alzheimer's—not. The most difficult factor in either untreatable dementia or Alzheimer's is age and how symptoms worsen with time. Age, however, is not the cause of dementia, but rather correlated with it. The cause of Alzheimer-related dementia is not known at this time, though hypotheses do exist.
The "amyloid cascade hypothesis" has been popular among scientists since the early 1990s as a possible explanation for Alzheimer's. The hypothesis points to beta-amyloid's effects on the brain when the peptides of the protein clump together and form oligomers that may be toxic to brain cells and lead to the development of plaques and tangles. Despite the popularity of this hypothesis and the evidence that supports it, the amyloid cascade hypothesis is not without challenge. In particular, some have pointed out that it is possible for tangles and plaques to develop independently of the beta-amyloid's oligomers.
A smaller camp in Alzheimer's research focuses on tau, the specific protein that forms tangles in the brain, as a cause for Alzheimer's. Tangles are formed in all brains as they age, not just the brains of patients who get Alzheimer's. From The Alzheimer's Enigma, a recently published article in Mosaic:
The spread of tangles [the protein tau] in the brain is much more closely related than plaques [the protein amyloid beta] to the progress of dementia in Alzheimer’s disease. When it was discovered that tau could cause damage, the amyloid hypothesis was updated to accommodate the idea that it might be tau, not amyloid beta, that actually kills nerve cells and causes dementia. “You could call the APP [amyloid] dysfunction the initiator of the whole thing but the tau dysfunction is the executioner,” says Goedert. There are some who go further, however, saying that tau is the real driving force behind Alzheimer’s disease. According to them, the reason the tau gene has not been linked to the disease is that tangles are a natural phenomenon of ageing in the brain. For most of us, this only becomes a problem in old age when the tangles have blocked lots of pathways, similar to the way our muscles become weak in old age. In Alzheimer’s disease, some other factor – maybe faulty or excessive amyloid beta – causes problems to occur earlier and progress faster.
About five percent of Alzheimer-related dementia is caused by a rare and hereditary genetic mutation—sometimes known as familial Alzheimer's disease, or FAD. Early onset symptoms are usually involved with these cases, with those aged 30 to 50 experiencing Alzheimer's symptoms. Mutations on three genes—PS1, PS2, and APP—have been linked to FAD, with PS1 being the most likely culprit. Those with a family history of this form of Alzheimer's or those with independent symptoms at a young age may find out more through genetic testing and genetic counseling.
A study published in JAMA Internal Medicine in 2015 concluded that higher cumulative anticholinergic use is associated with an increased risk for dementia and Alzheimer's disease. Many medications have anticholinergic effects, with the most common anticholinergic classes being tricyclic antidepressants, first-generation antihistamines, and bladder antimuscarinics.
While Alzheimer's disease is incurable and its progression is difficult to slow and treat, some of the other illnesses or injuries that cause dementia are treatable, even to the point of full reversal. Some common, treatable causes are found below.
- Medications and supplements, particularly antidepressants and common antihistamines used to treat allergies, as well as stimulants, can sometimes lead to dementia symptoms, especially in the elderly. This is not usually a side effect of a drug or supplement, but rather in how the body is processing it. When liver and kidney function declines with age, it is harder for the body to get rid of most drugs, leading to the buildup of substances. This unintended, higher concentration of a drug may result in dementia symptoms. Adjusting dosages may help reverse symptoms or slow their progression.
- Certain metabolic disorders, such as hypothyroidism or ongoing anemia, can seriously affect a patient's health if left untreated and even result in dementia symptoms. Treating these disorders often requires lifelong medication, but will likely clear up mental fogginess.
- Small strokes can cause dementia symptoms. Though damage caused by these small strokes cannot be reversed, the associated hardened arteries can be treated to prevent future strokes and further mental degeneration.
- Some nutritional deficiencies can result in dementia. B vitamin deficiencies, in particular, can negatively affect the nervous system and brain.
- Substance abuse can often lead to dementia symptoms. Seeking addiction treatment can help.
- Untreated infections, like HIV, Lyme disease, or syphilis, can damage the brain and cause dementia. While full reversal of dementia is very unlikely in these cases, dementia's progress can be slowed or stopped if the infection is properly treated.
- Exposure to high levels of mercury and other heavy metals can cause dementia and other health problems. In most cases, simply removing the source of exposure will be enough for the body to heal.
- Emotional distress caused by major life changes can contribute to confusion. Counseling and medication may help resolve this issue.
- Brain tumors and blood clots in the brain can affect a patient's thinking. Treatment for these problems varies greatly depending on severity.
Those concerned that they may be developing cognitive problems should seek medical attention as soon as possible. Only a medical doctor will be able to determine whether impairment is caused by some treatable health problem or by a more serious, degenerative disease, like Alzheimer's.
General Dementia Symptoms
- Memory loss is the earliest and most common sign of dementia. Forgetting appointments, what day of the week it is, that the stove is turned on, etc. are all signs of some cognitive impairment. This easily leads to impaired judgment.
- Irritability, depression, and other personality changes are common, especially if memory loss is worsening.
- In more severe or worsening cases, language difficulties may occur, and spatial understanding deteriorates.
It is important to remember that while some forms of dementia are treatable and even reversible, the vast majority of dementia—60% to 80%—is related to Alzheimer's disease.
Alzheimer's disease usually develops late in life and, in some cases, very slowly. This can easily result in the impression that an individual is just aging normally. Because Alzheimer's is a degenerative disease, its symptoms are best understood in stages.
Early stage symptoms may seem relatively normal and harmless at first, but worsen over time. During this stage, a person with Alzheimer's will begin to experience short-term memory problems and will likely struggle to remember recent events, manage personal tasks (e.g., finances, cooking, shopping), and keep track of items. He or she may also become disoriented in once comfortable and familiar places, which can lead to feelings of detachment and depression.
In July 2014, it was announced that scientists in the U.K. have produced a major breakthrough in early diagnosis of Alzheimer's disease. They identified a set of proteins whose presence in the blood can predict the start of the dementia with 87% accuracy.
The middle stage of Alzheimer's is when family members are most likely to notice significant changes in a loved one and will likely need to organize round-the-clock care. Anger, paranoia, inappropriate sexual behavior, hallucinations, and violence can be common in this stage. Questions or phrases may be repeated numerous times, and once simple decisions and activities (e.g., choosing what to wear, remembering to take a bath or eat) become difficult. As the stage progresses, there may be a loss of reading, writing, and arithmetic; verbal and spatial comprehension and abilities may decrease considerably. At this stage, the person with Alzheimer's may no longer consistently remember friends and family.
Late stage symptoms render a person with Alzheimer's nearly unrecognizable to friends and family. The ability to communicate, walk, recognize familiar people and objects, and even smile are likely to disappear. Extreme weight loss may occur, and most of the time the person will only want to sleep. In some cases, he or she will lose the ability to swallow and may suffer seizures. Ultimately, this stage of Alzheimer's, or the variety of other health issues that old age or Alzheimer's itself causes, leads to death.
Early Diagnosis with Brain Scans
In January 2015, researchers at USC announced that their research suggests that it may be possible to use brain scans to detect dementia even before symptoms become apparent. The brain’s protective blood barrier becomes leaky with age, starting at the hippocampus, a critical learning and memory center that is damaged by Alzheimer’s disease. Left untreated, this causes irreversible damage leading to progressive loss of memory, cognition and learning. It is possible to detect these vascular changes through brain scans.
Prognosis and Treatment
Depending on the root cause, some dementia may be treated and even cured. Alzheimer's, however, has no cure. Alzheimer's treatment instead focuses on slowing the disease's progression through medication (see antidementia agents), consistent daily routines, cognitive therapy puzzles, gentle physical exercises if the patient is able, etc. Consistent, safe emotional and logistic support is best implemented by primary caregivers. For those in care centers, studies have shown that routine visits are beneficial to the patient.
The pharmaceutical industry has tried various drugs over the last 15 years to treat or slow down the progression of Alzheimer's disease. A research paper published in July 2014 reached a pessimistic conclusion:
...relatively few clinical trials are undertaken for AD therapeutics, considering the magnitude of the problem. The success rate for advancing from one phase to another is low, and the number of compounds progressing to regulatory review is among the lowest found in any therapeutic area.
Alzheimer's drugs have focused on beta-amyloid protein but have failed to be effective. Some have been withdrawn because their side-effects were too detrimental; others did not show enough of an effect slowing patients’ mental decline. Solanezumab is one of the most recent drugs undergoing testing; it has shown only mild promise but is the first drug to have provided solid evidence that targeting beta-amyloid can slow the disease.
The Tau Protein
There is one drug that approaches Alzheimer's treatment by dissolving the tau protein instead of focusing on amyloid beta. This drug — called LMTX and manufactured by TauRx Therapeutics — showed promise in a 2008 trial of 321 patients and is currently under another phase of testing, results for which will be reported in 2015. However, critics and skeptics have asked for results from the 2008 study to be published so they can be peer-reviewed by the scientific community. Until that happens, there is only the manufacturer's word that the drug works.
Good nutritional and lifestyle choices, including nurturing brain health, may delay, slow, or possibly even prevent Alzheimer's. Evidence suggests several basic measures of prevention may go a long way.
- Healthy eating keeps the body in good condition. Minimizing the intake of processed foods, sugar, and excess sodium is wise and likely to help the body as it ages. There is an increased risk of dementia and Alzheimer's among those who are obese, have type 2 diabetes, and/or cardiovascular problems.
- Exercising for at least 3-4 hours a week and maintaining an active lifestyle can make a difference by keeping the heart healthy and providing more blood and oxygen to the brain. Walking, jogging, and cycling are all good exercises to begin with. When choosing to play a sport for exercise, consider avoiding those that come with a higher risk of head trauma (e.g., gridiron football), as there appears to be a strong correlation between head trauma and Alzheimer's disease.
- Staying social is good for mental health. Some studies suggest that having strong social connections to other people in a community might decrease the risk of dementia and Alzheimer's.
- Mental stimulation is also important. Solving puzzles, doing math, and reading provide challenges for the brain, which in turn may decrease the buildup of beta-amyloid. Similarly, some studies have found those who have attained more formal education are less likely to develop cognitive problems later in life.
- Alzheimer's Disease - Alzheimer's Association
- The Alzheimer's Enigma - Mosaic Science
- The five most likely ways to beat dementia - New Scientist
- Preventing Alzheimer's - NIH.gov
- Preventing Dementia - Stanford Hospital
- Scans detect aging brain issues linked to dementia - University of Southern California
- Dementia "linked" to over-the-counter medications - BBC News
- Wikipedia: Alzheimer's disease
- Wikipedia: Dementia