Introduction
Alzheimer’s disease is a brain disorder that gets worse over time. It’s characterized by changes in the brain that lead to deposits of certain proteins. Alzheimer’s disease causes the brain to shrink and brain cells to eventually die. Alzheimer’s disease is the most common cause of dementia a gradual decline in memory, thinking, behaviour and social skills. These changes affect a person’s ability to function.
Causes
The exact causes of Alzheimer’s disease aren’t fully understood. But at a basic level, brain proteins fail to function as usual. This disrupts the work of brain cells, also called neurons, and triggers a series of events. The neurons become damaged and lose connections to each other. They eventually die. 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. In less than 1% of cases, Alzheimer’s is caused by specific genetic changes that almost guarantee a person will develop the disease. In these cases, the disease usually begins in middle age.
The development of the disease begins years before the first symptoms. The damage most often starts in the region of the brain that controls memory. 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 trying to understand the cause of Alzheimer’s disease are focused on the role of two proteins:
• Plaques. Beta-amyloid is a fragment of a larger protein. When these fragments clump together, they appear to have a toxic effect on neurons and to disrupt communication between brain cells. These clumps form larger deposits called amyloid plaques, which also include other cellular debris.
• Tangles. Tau proteins play a part in a brain cell’s internal support and transport system to carry nutrients and other essential materials. In Alzheimer’s disease, tau proteins change shape and organize into structures called neurofibrillary tangles. The tangles disrupt the transport system and cause damage to cells.
Disease Symptoms
Memory loss is the key symptom of Alzheimer’s disease. Early signs include difficulty remembering recent events or conversations. But memory gets worse and other symptoms develop as the disease progresses. At first, someone with the disease may be aware of having trouble remembering things and thinking clearly. As symptoms get worse, a family member or friend may be more likely to notice the issues. Brain changes associated with Alzheimer’s disease lead to growing trouble with:
Memory
Everyone has memory lapses at times, but the memory loss associated with Alzheimer’s disease persists and gets worse. Over time, memory loss affects the ability to function at work or at home. People with Alzheimer’s disease may:
• Repeat statements and questions over and over.
• Forget conversations, appointments or events.
• Misplace items, often putting them in places that don’t make sense.
• Get lost in places they used to know well.
• Eventually forget the names of family members and everyday objects.
• Have trouble finding the right words for objects, expressing thoughts or taking part in conversations.
Thinking and reasoning: Alzheimer’s disease causes difficulty concentrating and thinking, especially about abstract concepts such as numbers. Doing more than one task at once is especially difficult. It may be challenging to manage finances, balance checkbooks and pay bills on time. Eventually, a person with Alzheimer’s disease may be unable to recognize and deal with numbers.
Making judgments and decisions: Alzheimer’s disease causes a decline in the ability to make sensible decisions and judgments in everyday situations. For example, a person may make poor choices in social settings or wear clothes for the wrong type of weather. It may become harder for someone to respond to everyday problems. For example, the person may not know how to handle food burning on the stove or decisions when driving.
Planning and performing familiar tasks: Routine activities that require completing steps in order become a struggle. This may include planning and cooking a meal or playing a favorite game. Eventually, people with advanced Alzheimer’s disease forget how to do basic tasks such as dressing and bathing.
Changes in personality and behaviour: Brain changes that occur in Alzheimer’s disease can affect moods and behaviors. Problems may include the following:
• Depression.
• Loss of interest in activities.
• Social withdrawal.
• Mood swings.
• Distrust in others.
• Anger or aggression.
• Changes in sleeping habits.
• Wandering.
• Loss of inhibitions.
• Delusions, such as believing something has been stolen.
Preserved skills: Despite major changes to memory and skills, people with Alzheimer’s disease are able to hold on to some skills even as symptoms get worse. Preserved skills may include reading or listening to books, telling stories, sharing memories, singing, listening to music, dancing, drawing, or doing crafts.
Alzheimer’s disease diagnosis
Doctors use several methods and tools to help determine whether a person who is having memory problems has Alzheimer’s. To diagnose Alzheimer’s, doctors may:
• Ask the person and a family member or friend questions about overall health, use of prescription and over-the-counter medicines, diet, past medical problems, ability to carry out daily activities, and changes in behavior and personality.
• Conduct tests of memory, problem solving, attention, counting, and language.
• Order blood, urine, and other standard medical tests to help identify other possible causes of the problem.
• Administer tests to determine if depression or another mental health condition is causing or contributing to a person’s symptoms.
• Collect cerebrospinal fluid via a spinal tap or order blood tests to measure the levels of proteins associated with Alzheimer’s and related dementias.
• Perform brain scans, such as CT, MRI, or PET (positron emission tomography), to support an Alzheimer’s diagnosis or to rule out other possible causes for symptoms.
These tests may be repeated to give doctors information about how the person’s memory and other cognitive functions are changing over time.
Alzheimer’s Complications
Alzheimer’s symptoms such as memory loss, language loss, impaired judgment and other brain changes can make it harder to manage other health conditions. A person with Alzheimer’s disease may not be able to:
• Tell someone about being in pain.
• Explain symptoms of another illness.
• Follow a treatment plan.
• Explain medicine side effects.
As Alzheimer’s disease moves into its last stages, brain changes begin to affect physical functions. The changes can affect the ability to swallow, balance, and control bowel and bladder movements. These effects can lead to other health problems such as:
• Inhaling food or liquid into the lungs.
• Flu, pneumonia and other infections.
• Falls.
• Fractures.
• Bedsores.
• Poor nutrition or dehydration.
• Constipation or diarrhea.
• Dental problems such as mouth sores or tooth decay.
Stages of Alzheimer
Alzheimer’s disease can range from mild to severe. The scale ranges from a state of mild impairment, through to moderate impairment, before eventually reaching severe cognitive decline. The sections below will discuss the stages of Alzheimer’s and some of the symptoms that characterize them.
Mild Alzheimer’s disease
People with mild Alzheimer’s disease develop memory problems and cognitive difficulties that may include the following:
• taking longer than usual to perform daily tasks
• difficulty handling money or paying the bills
• wandering and getting lost
• experiencing personality and behavior changes, such as getting upset or angry more easily, hiding things, or pacing
Moderate Alzheimer’s disease
In moderate Alzheimer’s disease, the parts of the brain responsible for language, senses, reasoning, and consciousness are damaged. This can lead to the following symptoms:
• greater memory loss and confusion
• difficulty recognizing friends or family
• an inability to learn new things
• difficulty performing tasks with several stages, such as getting dressed
• difficulty coping with new situations
• impulsive behavior
• hallucinations, delusions, or paranoia
Severe Alzheimer’s disease
In severe Alzheimer’s disease, plaques and tangles are present throughout the brain, causing the brain tissue to shrink substantially. This can lead to:
• an inability to communicate
• dependency on others for care
• being unable to leave bed all or most of the time
Prevention
Alzheimer’s disease is not a preventable condition. However, a number of lifestyle risk factors can be modified. Evidence suggests that taking steps to reduce the risk of cardiovascular disease may also lower your risk of developing dementia. To follow heart-healthy lifestyle choices that may reduce the risk of dementia:
• Exercise regularly.
• Eat a diet of fresh produce, healthy oils and foods low in saturated fat, such as a Mediterranean diet.
• Follow treatment guidelines to manage high blood pressure, diabetes and high cholesterol.
• If you smoke, ask your health care professional for help to quit.
One large, long-term study done in Finland found that making lifestyle changes helped reduce cognitive decline among people who were at risk of dementia. Those in the study were given individual and group sessions that focused on diet, exercise and social activities.
In another study done in Australia, people at risk of dementia were given coaching sessions on diet, exercise and other lifestyle changes. They had better results on cognitive tests after one, two and three years compared to people who didn’t receive the coaching. Other studies have shown that staying engaged mentally and socially is linked to preserve thinking skills later in life and a lower risk of Alzheimer’s disease. This includes going to social events, reading, dancing, and playing board games, creating art, playing an instrument and other activities.
How is Alzheimer’s disease treated?
Alzheimer’s is complex, and it is therefore unlikely that any one drug or other intervention will successfully treat it in all people living with the disease. In ongoing clinical trials, scientists are developing and testing several possible treatment interventions. While there is currently no cure for Alzheimer’s, medications are emerging to treat the progression of the disease by targeting its underlying causes. There are also medications that may temporarily improve or stabilize memory and thinking skills in some people and may help manage certain symptoms and behavioral problems.
Additionally, people with Alzheimer’s also may experience sleeplessness, depression, anxiety, agitation, and other behavioral and psychological symptoms. Scientists continue to research why these symptoms occur and are exploring new medications and non-drug strategies to manage them. Research shows that treating these symptoms may make people with Alzheimer’s feel more comfortable and also help their caregivers. Antidepressants, antipsychotics, and anti-anxiety drugs may be helpful for some people with Alzheimer’s, but experts agree that these medicines should be used only after other strategies to promote physical and emotional comfort, such as avoiding stressful situations, have been tried. It’s important to talk with a doctor about what treatment will be most effective in your situation.
Medications for cognitive symptoms
No disease-modifying drugs are available for Alzheimer’s disease, but some options may reduce the symptoms and help improve quality of life. Drugs called cholinesterase inhibitors can ease cognitive symptoms, including memory loss, confusion, altered thought processes, and judgment problems. They improve neural communication across the brain and slow the progress of these symptoms. Three common drugs with Food and Drug Administration (FDA) approval to treat these symptoms of Alzheimer’s disease are:
• donepezil (Aricept), to treat all stages
• galantamine (Razadyne), to treat mild-to-moderate stages
• rivastigmine (Exelon), to treat mild-to-moderate stages
Another drug, called memantine (Namenda), has approval to treat moderate-to-severe Alzheimer’s disease. A combination of memantine and donepezil (Namzaric) is also available.
Support for families and Alzheimer’s disease caregivers
Caring for a person with Alzheimer’s can have significant physical, emotional, and financial costs. The demands of day-to-day care, changes in family roles, and decisions about placement in a care facility can be difficult. NIA supports efforts to evaluate programs, strategies, approaches, and other research to improve the quality of care and life for those living with dementia and their caregivers.
Becoming well-informed about the disease is one important long-term strategy. Programs that teach families about the various stages of Alzheimer’s and about ways to deal with difficult behaviors and other caregiving challenges can help. Good coping skills, a strong support network, and respite care are other things that may help caregivers handle the stress of caring for a loved one with Alzheimer’s. For example, staying physically active provides physical and emotional benefits.
Some caregivers have found that joining a support group is a critical lifeline. These support groups enable caregivers to find respite, express concerns, share experiences, get tips, and receive emotional comfort. Many organizations sponsor in-person and online support groups, including groups for people with early-stage Alzheimer’s and their families.
