Alzheimer’s disease is the most common cause of dementia — a continuous decline in thinking, behavioral and social skills that disrupts a person’s ability to function independently. Even though there is no cure for this condition, there are several ways to try to prevent and delay the disease from spreading. Learn more about the causes, symptoms, risk factors, tests, and preventive measures related to Alzheimer’s disease here.
What is Alzheimer’s Disease
Alzheimer’s disease is a progressive disorder that causes brain cells to waste away (degenerate) and die. Alzheimer’s disease is the most common cause of dementia — a continuous decline in thinking, behavioral and social skills that disrupts a person’s ability to function independently.
The early signs of the disease may be forgetting recent events or conversations. As the disease progresses, a person with Alzheimer’s disease will develop severe memory impairment and lose the ability to carry out everyday tasks.
Current Alzheimer’s disease medications may temporarily improve symptoms or slow the rate of decline. These treatments can sometimes help people with Alzheimer’s disease maximize function and maintain independence for a time. There is no treatment that cures Alzheimer’s disease or alters the disease process in the brain. In advanced stages of the disease, complications from severe loss of brain function — such as dehydration, malnutrition or infection — result in death.
Symptoms of Alzheimer’s Disease
Everyone has occasional memory lapses. It’s normal to lose track of where you put your keys or forget the name of an acquaintance. But the memory loss associated with Alzheimer’s disease persists and worsens, affecting the ability to function at work or at home.
People with Alzheimer’s may:
- Repeat statements and questions over and over
- Forget conversations, appointments or events, and not remember them later
- Routinely misplace possessions, often putting them in illogical locations
- Get lost in familiar places
- Eventually, forget the names of family members and everyday objects
- Have trouble finding the right words to identify objects, express thoughts or take part in conversations
Thinking and reasoning
Alzheimer’s disease causes difficulty concentrating and thinking, especially about abstract concepts such as numbers. Multitasking is especially difficult, and it may be challenging to manage finances, balance checkbooks and pay bills on time. These difficulties may progress to an inability to recognize and deal with numbers.
Making judgments and decisions
The ability to make reasonable decisions and judgments in everyday situations will decline. For example, a person may make poor or uncharacteristic choices in social interactions or wear clothes that are inappropriate for the weather. It may be more difficult to respond effectively to everyday problems, such as food burning on the stove or unexpected driving situations.
Planning and performing familiar tasks
Once-routine activities that require sequential steps, such as planning and cooking a meal or playing a favorite game, become a struggle as the disease progresses. Eventually, people with advanced Alzheimer’s may forget how to perform basic tasks such as dressing and bathing.
Changes in personality and behavior
Brain changes that occur in Alzheimer’s disease can affect moods and behaviors. Problems may include the following:
- Social withdrawal
- Mood swings
- Distrust in others
- Irritability and aggressiveness
- Changes in sleeping habits
- Loss of inhibitions
- Delusions, such as believing something has been stolen
Many important skills are preserved for longer periods even while symptoms worsen. Preserved skills may include reading or listening to books, telling stories and reminiscing, singing, listening to music, dancing, drawing, or doing crafts. These skills may be preserved longer because they are controlled by parts of the brain affected later in the course of the disease.
Causes for Alzheimer’s Disease
Scientists believe that for most people, Alzheimer’s disease is caused by a combination of genetic, lifestyle and environmental factors that affect the brain over time. Less than 1 percent of the time, Alzheimer’s is caused by specific genetic changes that virtually guarantee a person will develop the disease. These rare occurrences usually result in disease onset in middle age.
The exact causes of Alzheimer’s disease aren’t fully understood, but at its core are problems with brain proteins that fail to function normally, disrupt the work of brain cells (neurons) and unleash a series of toxic events. Neurons are damaged, lose connections to each other and eventually die.
The damage most often starts in the region of the brain that controls memory, but the process begins years before the first symptoms. The loss of neurons spreads in a somewhat predictable pattern to other regions of the brain. By the late stage of the disease, the brain has shrunk significantly.
Researchers are focused on the role of two proteins:
- Plaques: Beta-amyloid is a leftover fragment of a larger protein. When these fragments cluster together, they appear to have a toxic effect on neurons and to disrupt cell-to-cell communication. These clusters form larger deposits called amyloid plaques, which also include other cellular debris.
- Tangles: Tau proteins play a part in a neuron’s internal support and transport system to carry nutrients and other essential materials. In Alzheimer’s disease, tau proteins change shape and organize themselves into structures called neurofibrillary tangles. The tangles disrupt the transport system and are toxic to cells.
Alzheimer’s Disease Risk Factors
The biggest risk for Alzheimer’s disease is increasing age. The risk for Alzheimer’s disease doubles every five years after age 65, and the incidence is nearly one in three after age 85. One study found that annually there were 2 new diagnoses per 1,000 people ages 65-74, 11 per 1,000 people ages 75-84, and 37 per 1,000 people age 85+.
Family history and genetics
Family history is also a significant risk factor. People who have a parent or sibling with Alzheimer’s disease are at higher risk, as are those who have multiple affected family members. Most genetic mechanisms of Alzheimer’s among families remain largely unexplained, and the genetic factors are likely complex.
One better understood genetic factor is a form of the apolipoprotein E gene (APOE). A variation of the gene, APOE e4, increases the risk of Alzheimer’s disease, but not everyone with this variation of the gene develops the disease.
In my case in specific, my father suffered from Alzheimer’s disease. I did a DNA test with MyHeritage. Unfortunately, I found out that I’m likely to develop late on-set Alzheimer’s as well, as I have two copies of that gene APOE e4:
This means that I have a significantly increased risk to develop Alzheimer’s disease. While this risk is higher than of the general population, it does not necessarily mean that I’ll develop Alzheimer’s disease. Genetic risk estimates are calculated using the latest research on how common this condition is in the general population.
This is my risk, compared to the general population:
When two copies of a pathogenic variant are detected, like in my case, this suggests that my family members may also have an increased genetic risk to develop Alzheimer’s disease.
This means that it is almost certain that any children I have one day will also inherit this variant, unfortunately.
Many people with Down syndrome develop Alzheimer’s disease. This is likely related to having three copies of chromosome 21 — and subsequently three copies of the gene for the protein that leads to the creation of beta-amyloid. Signs and symptoms of Alzheimer’s tend to appear 10 to 20 years earlier in people with Down syndrome than they do for the general population.
Women seem to have a higher risk of developing Alzheimer’s disease than men. This risk may be anywhere from 1.5 up to 3 times as high as that of men of the same age. A contributing factor to this risk may be that women generally live longer than men and therefore have greater risk as they get older.
Latinos have a 1.5 times greater risk of developing Alzheimer’s disease while African American’s risk is two times that of Caucasians. The reason for this difference is not well understood but may be linked to the higher incidence of heart disease in those two ethnic groups.
Brain inactivity and trauma
There appears to be a link between lower educational levels and a lack of brain stimulation and the development of Alzheimer’s disease. Additionally, people who’ve had a severe head trauma have a greater risk of Alzheimer’s disease.
Poor sleep patterns
Research has shown that poor sleep patterns, such as difficulty falling asleep or staying asleep, are associated with an increased risk of Alzheimer’s disease.
Lifestyle and heart health
Damage to the blood vessels of the brain that result from heart or vascular conditions like stroke, heart disease, and high blood pressure also seems to result in a higher risk of Alzheimer’s disease. Some studies show that high blood pressure in middle age is strongly correlated with Alzheimer’s disease.
Research has shown that the same risk factors associated with heart disease may also increase the risk of Alzheimer’s disease. These include:
- Lack of exercise
- Smoking or exposure to secondhand smoke
- High blood pressure
- High cholesterol
- Poorly controlled type 2 diabetes
*Being overweight can double the risk for Alzheimer’s disease. Individuals who are considered obese may have up to three times the risk compared to those in a normal weight range.
Alzheimer’s Disease Diagnosis
A key component of a diagnostic assessment is self-reporting about symptoms, as well as the information that a close family member or friend can provide about symptoms and their impact on daily life. Additionally, a diagnosis of Alzheimer’s disease is based on tests a doctor administers to assess memory and thinking skills.
Laboratory and imaging tests can rule out other potential causes or help the doctor better characterize the disease that’s causing dementia symptoms.
The entire set of diagnostic tools is designed to detect dementia and determine with relatively high accuracy whether Alzheimer’s disease or another condition is the cause. Alzheimer’s disease can be diagnosed with complete certainty only after death when microscopic examination of the brain reveals the characteristic plaques and tangles.
A diagnostic work-up would likely include the following tests:
- Physical and neurological exam: to assess overall neurological health by testing the reflexes, muscle tone and strength, ability to get up from a chair and walk across the room, sense of sight and hearing, coordination, and balance.
- Lab tests: blood tests done to rule out other potential causes of memory loss and confusion, such as a thyroid disorder or vitamin deficiencies.
- Mental status and neuropsychological tests: to assess memory and other thinking skills. These tests are also important for establishing a starting point to track the progression of symptoms in the future.
- Brain imaging tests: images of the brain to pinpoint visible abnormalities related to conditions other than Alzheimer’s disease — such as strokes, trauma or tumors — that may cause cognitive change. New imaging applications — currently used primarily in major medical centers or in clinical trials — may enable doctors to detect specific brain changes caused by Alzheimer’s. Imaging of brain structures include the following:
- Magnetic resonance image (MRI) scans, that are used to rule out other conditions;
- Computerized Tomography (CT) scans, to check the ‘slices’ of your brain and rule out tumors, strokes, and head injuries;
- Positron Emission Tomography (PET) scans, where a low-level radioactive tracer is injected into the blood to reveal a particular feature in the brain. There are several types of PET scans. Fluorodeoxyglucose (FDG) PET scans show areas of the brain in which nutrients are poorly metabolized. Identifying patterns of degeneration — areas of low metabolism — can help distinguish between Alzheimer’s disease and other types of dementia. Amyloid PET can measure the burden of amyloid deposits in the brain. This imaging is primarily used in research but may be used if a person has an unusual or very early onset of dementia symptoms. Tau PET, which measures the burden of neurofibrillary tangles in the brain, and is only used in research;
- In special circumstances, such as rapidly progressive dementia or very early onset dementia, other tests may be used to measure abnormal beta-amyloid or tau in the cerebrospinal fluid.
- Future diagnostic tests: researchers are working on tests that can measure the biological evidence of disease processes in the brain. These tests may improve the accuracy of diagnoses and enable earlier diagnosis before the onset of symptoms.
Alzheimer’s Disease Prevention and Treatment
Alzheimer’s disease is not a preventable condition. However, a number of lifestyle risk factors for Alzheimer’s can be modified. Evidence suggests that changes in diet, exercise and habits — steps to reduce the risk of cardiovascular disease — may also lower your risk of developing Alzheimer’s disease and other disorders that cause dementia. Heart-healthy lifestyle choices that may reduce the risk of Alzheimer’s include the following:
- Exercise regularly: activities such as a daily walk can help improve mood and maintain the health of joints, muscles and the heart. Exercise can also promote restful sleep and prevent constipation;
- Eat a diet of fresh produce, healthy oils and foods low in saturated fat: changing some habits can to some degree alter your risk. For example, having a healthy low-fat diet rich in fruits and vegetables is associated with a decreased risk of developing Alzheimer’s disease. Drinking lots of water every day is also very important. Avoid beverages with caffeine, which can increase restlessness, interfere with sleep and trigger a frequent need to urinate;
- Follow treatment guidelines to manage high blood pressure, diabetes and high cholesterol;
- If you smoke, ask your doctor for help to quit smoking;
- Studies have shown that certain activities can help reducing the risk of Alzheimer’s disease and support the skills that are preserved, like participating in social events, reading, dancing, playing board games, creating art, gardening, or playing an instrument.
Current Alzheimer’s medications can help for a time with memory symptoms and other cognitive changes. Two types of drugs are currently used to treat cognitive symptoms:
- Cholinesterase Inhibitors: These drugs work by boosting levels of cell-to-cell communication by preserving a chemical messenger that is depleted in the brain by Alzheimer’s disease. The improvement is modest. Cholinesterase inhibitors may also improve neuropsychiatric symptoms, such as agitation or depression. Commonly prescribed cholinesterase inhibitors include the following (however, the main side effects of these drugs include diarrhea, nausea, loss of appetite and sleep disturbances, and for people with cardiac conduction disorders, serious side effects may include cardiac arrhythmia):
- Donepezil (Aricept);
- Galantamine (Razadyne);
- Rivastigmine (Exelon).
- Memantine (Namenda): This drug works in another brain cell communication network and slows the progression of symptoms with moderate to severe Alzheimer’s disease. It’s sometimes used in combination with a cholinesterase inhibitor. Relatively rare side effects include dizziness and confusion.
Sometimes other medications such as antidepressants may be prescribed to help control the behavioral symptoms associated with Alzheimer’s disease.
Mayo Clinic does clinical trials, testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this disease.
Various herbal remedies, vitamins and other supplements are widely promoted as preparations that may support cognitive health or prevent or delay Alzheimer’s. Clinical trials have produced mixed results with little evidence to support them as effective treatments.
Some of the treatments that have been studied recently include:
- Omega-3 fatty acids: Omega-3 fatty acids in fish or from supplements may lower the risk of developing dementia, but clinical studies have shown no benefit for treating Alzheimer’s disease symptoms;
- Curcumin: This herb comes from turmeric and has anti-inflammatory and antioxidant properties that might affect chemical processes in the brain. So far, clinical trials have found no benefit for treating Alzheimer’s disease;
- Ginkgo: Ginkgo is a plant extract containing several medicinal properties. A large study funded by the National Institutes of Health found no effect in preventing or delaying Alzheimer’s disease;
- Vitamin E: Although vitamin E isn’t effective for preventing Alzheimer’s, taking 2,000 international units daily may help delay the progression in people who already have the disease.
However, study results have been mixed, with only some showing this benefit. Further research into the safety of 2,000 international units daily of Vitamin E in a dementia population will be needed before it can be routinely recommended.