What is Alzheimer’s Disease?
Alzheimer’s disease is a degenerative condition that affects memory, thinking, and behavior. The disorder is named for Alois Alzheimer, the German doctor who identified it in 1906. Alzheimer’s is a type of dementia that progresses gradually, eventually having a profound effect on the sufferer’s ability to function, both cognitively and physically. Over time, people with Alzheimer’s need an increasing level of care.
Alzheimer’s usually develops slowly over a period of years. Symptoms include:
The most significant risk factor for Alzheimer’s is advancing age. Symptoms tend to appear in the mid-60s. When symptoms appear before the age of 65, the disease is known as early-onset Alzheimer’s. Late-onset Alzheimer’s is by far the more common form of the disease.
What Causes Alzheimer’s Disease?
The interplay of age, genetics, environmental influences, and inflammation in Alzheimer’s disease is poorly understood. However, it is known that chronic infection, environmental triggers, diabetes, stress, and a history of depression can affect the immune system and contribute to the onset of dementia.
Scientists are studying how age-related changes harm nerve cells and damage the brain. Aging naturally causes the shrinking of some regions of the brain (a process called atrophy). This natural process may work in conjunction with abnormal biochemical processes in the brain to cause Alzheimer’s.
In the brains of Alzheimer’s patients, a toxic protein called beta-amyloid clumps with other protein fragments to form “amyloid plaques.” These hard clumps of protein lodge between the brain’s nerve cells and impair their function.
Abnormal tangles of another protein, “tau,” appear throughout the brains of Alzheimer’s patients. The tangles interfere with the processes that keep nerve cells alive. Damaged nerve cells lose their connections with other cells and die.
The causes of Alzheimer’s include genetic, lifestyle, and environmental factors. Although drug companies have searched for a single “Alzheimer’s gene” that causes the disease, more than 95 percent of people with the condition have no known genetic risk factors.
Another potential cause of the disorder is chronic inflammation in the brain. The immune system naturally declines with age, limiting the body’s ability to fight infection. Chronic inflammation can alter the brain’s biochemistry, and elevated levels of inflammatory proteins have been linked to Alzheimer’s disease and dementia.
Other potential causes of Alzheimer’s include:
- Unstable molecules called “free radicals” that affect energy production within brain cells
- A metabolic gene that may contribute to a family history of Alzheimer’s
- Two strains of the herpes virus that generally cause brief illnesses in toddlers
Is Alzheimer’s Disease Hereditary?
Genetic factors influence whether someone will develop Alzheimer’s. Even subtle changes in genes can cause the production of abnormal proteins. A single gene can have many variants. Some gene variants increase or decrease Alzheimer’s risk. More than 20 genetic variants are linked with late-onset Alzheimer’s. However, no one single gene has ever been directly linked to late-onset Alzheimer’s.
Many cases of early-onset Alzheimer’s are linked to gene mutations passed down from a mother or father. Early-onset Alzheimer’s can result from an inherited change in specific genes in three different locations within cells. Someone who inherits one of these three mutations has a very high probability of developing Alzheimer’s before age 65. However, early-onset familial Alzheimer’s disease accounts for less than 5% of all disease cases.
How is Alzheimer’s Disease Detected?
Currently, no test can predict whether someone will get late-onset Alzheimer’s. A physician should be consulted when signs of memory loss occur in an older adult. While occasional forgetfulness may not cause concern, persistent memory problems should be evaluated by a doctor. Typically, more severe cognitive and attention deficits follow.
Genetic testing is available for people with a family history of early-onset Alzheimer’s (age 30 to 65). Genetic counselors can help people make decisions about testing and options for the future.
How is Alzheimer’s Disease Diagnosed?
To diagnose Alzheimer’s, a doctor will look for signs of cognitive impairment. Exams and tests will determine the severity of the impairment and rule out other potential causes for the symptoms.
Initial exams will look for symptoms including:
- Impairment of memory or thinking
- Changes in behavior or personality
- Impairment of daily functioning
Additional tests may be ordered to rule out other potential causes of the symptoms, including Parkinson’s disease, strokes, thyroid disorders, or depression.
Other diagnostic steps may include:
- More extensive cognitive exams
- Consultation with a neuropsychologist or neurologist
- Imaging exams to look for signs of the disease
- Interviews with family members or friends
PLEASE CONSULT A PHYSICIAN FOR MORE INFORMATION.
How Is Alzheimer’s Disease Treated?
Current treatment approaches focus on managing behavioral symptoms and helping people maintain mental function. Treating the symptoms of Alzheimer’s can provide people with comfort, dignity, and independence for a longer time.
Medications work best for people in the early to middle stages of Alzheimer’s. They can slow down some symptoms, such as memory loss, for a time. No medications, however, can stop the disease itself.
The U.S. Food and Drug Administration (FDA) has approved several prescription drugs to treat symptoms of Alzheimer’s.
- Cholinesterase inhibitors are prescribed for mild to moderate Alzheimer’s disease. These drugs include galantamine, rivastigmine, and donepezil. While scientists do not fully understand how cholinesterase inhibitors work, research shows that they prevent the breakdown of a brain chemical called acetylcholine, which is vital to memory and thinking. Over time, cholinesterase inhibitors lose their effectiveness.
- Memantine is sometimes prescribed for moderate to severe Alzheimer’s disease. This drug may help a person in the later stages of the disease maintain basic functioning for a limited time. Because these drugs work differently from cholinesterase inhibitors, the two types of medicines can be prescribed in combination.
Research has shown that treating behavioral symptoms can help keep people with Alzheimer’s more comfortable while easing caregivers’ tasks. Medications used to treat depression, aggression, restlessness, and anxiety include citalopram, mirtazapine, sertraline, bupropion, duloxetine, and imipramine.
Experts warn that medications for behavioral problems should be tried only after non-drug strategies have failed. It is essential to follow the doctor’s instructions when taking any medication, including vitamins and herbal supplements. Let the doctor know before adding or changing any medications.
How Is Alzheimer’s Disease Treated?
Scientists continue to unravel the complex brain changes involved in the onset and progression of Alzheimer’s disease. Brain damage begins a decade or more before memory and other cognitive problems appear. During this “preclinical” stage of the disease, people seem to be symptom-free, but toxic changes are taking place in the brain.
At this stage, abnormal deposits of proteins form amyloid plaques, and tau tangles appear throughout the brain. Brain nerve cells (neurons) stop working, lose connections with other neurons, and die off.
Brain damage initially seems to occur in the hippocampus, which is essential to forming memories. As more neurons die, other areas of the brain decline. By the final stage of Alzheimer’s, the damage is widespread, and brain tissue has shrunk significantly.
Mild Cognitive Impairment (MCI)
Memory problems are typically one of the first signs of cognitive impairment related to Alzheimer’s disease. Some people with memory problems have a condition called mild cognitive impairment (MCI). People with MCI have more memory problems than expected for their age, but symptoms do not interfere with their everyday lives. Older people with MCI are at greater risk of developing Alzheimer’s, but not all do. Some even regain their normal cognitive abilities.
How is Alzheimer’s Disease Prevented?
Researchers are studying the relationship between cognitive decline and vascular conditions such as heart disease, stroke, and high blood pressure. Metabolic disorders such as diabetes and obesity promote inflammation that may be associated with Alzheimer’s.
Scientists are studying ways to stave off cognitive decline. A nutritious diet, physical activity, social engagement, and mentally stimulating pursuits have all been associated with helping people stay healthy as they age.
Follow these tips to stay as healthy as possible:
- Exercise regularly.
- Eat a healthy diet rich in fruits, leafy greens, fish, and nuts.
- Spend time with family and friends.
- Keep your mind active and engaged.
- Control Type 2 diabetes.
- Keep blood pressure and cholesterol at healthy levels.
- Maintain a healthy body weight.
- Stop smoking.
- Seek treatment for depression.
- Avoid alcohol.
- Get plenty of sleep.
- Watch for significant changes in memory, thinking, and reasoning.
Alzheimer’s Disease Caregiver Tips
The most important thing you can do for a loved one with Alzheimer’s is to show love and support. The disorder affects every aspect of daily life. Ways to help include:
- Create a supportive, comforting environment. Adopt a warm, loving, matter-of-fact manner. Be patient with angry outbursts. Remember, it’s the” illness talking.”
- Keep things simple. Embrace a daily routine, so your loved one knows when something will happen.
- Help to improve your loved one’s sleep schedule. Limit naps and plan activities that use energy early in the day. For example, try bathing in the morning or having the largest meal in the middle of the day.
- Let your loved one know that he or she is safe. Try not to argue with the person about what he or she sees or hears. Comfort the individual instead.
- Do not leave a person with Alzheimer’s who has a history of wandering unattended. Make sure your loved one carries an ID or wears a medical bracelet. Let neighbors and the local police know if a loved one with Alzheimer’s tends to wander. Place labels in garments to aid in identification.
Alzheimer’s Disease Brain Science
Years before Alzheimer’s symptoms start to appear, subtle changes occur in the brain:
- Toxic fragments of beta-amyloid protein trigger neurological damage in the brain. Clumps of protein form “amyloid plaques” that build up between neurons.
- Tau is a necessary protein for healthy brain cells. In Alzheimer’s disease, the protein becomes deformed and tangled, preventing tau from doing its job.
- Amyloid plaques and tau tangles create a toxic environment in the brain, causing neurons to wither and lose their connections to neighboring neurons.
Researchers have tried targeting beta-amyloid and tau in an attempt to treat Alzheimer’s disease. So far, these experimental therapies have been unsuccessful.
Clinical trials are also underway to find preventative ways to block the formation of amyloid plaques in the brain. Researchers are studying whether medications approved for other diseases may help treat Alzheimer’s.
Alzheimer’s Disease Research
Title: Identifying Preclinical Stages of Alzheimer’s
Reisa Sperling, MD, MMSC
Director, Massachusetts Alzheimer’s Disease Research Center
Professor of Neurology, Harvard University
One of the most challenging aspects of treating Alzheimer’s disease is timing. Alzheimer’s therapies are most effective when started at the onset of the disease, but symptoms of Alzheimer’s disease only become evident after damaging changes have occurred in the brain. Dr. Reisa Sperling is tackling this problem, working to identify the first preclinical stages of Alzheimer’s disease using cutting-edge functional MRI (fMRI) and PET imaging technologies to achieve an early diagnosis. Neuroimaging studies with these sophisticated tools reveal structural abnormalities associated with cognitive problems.
In addition to studying early Alzheimer’s disease detection methods, Dr. Sperling is leading an innovative clinical study testing a new drug, solanezumab, which may reduce amyloid levels in the brain. Deep brain stimulation (DBS) is used in Parkinson’s disease, epilepsy, and several other conditions that affect the central nervous system. Dr. Sperling is exploring DBS as a potential strategy for the treatment of early Alzheimer’s.
Deep brain stimulation (DBS) involves implanting electrodes in specific areas of the brain. The implant is implanted while the patient is fully awake. The device sends an electrical impulse to the region of the brain associated with memory.
Title: PET Imaging to Detect the Earliest Visible Stages of Alzheimer’s disease
Paul Rosenberg, MD
Alzheimer’s Disease Research Center
Johns Hopkins School of Medicine
Often, people with Alzheimer’s disease also experience depression. Since dementia and depression share many of the same symptoms, psychiatric disorders frequently go undetected.
Dr. Paul Rosenberg has recognized this shortcoming and is investigating the link between dementia, depression, and other neuropsychiatric disorders. His research has shown that dementia diagnoses must be considered when choosing concurrent depression and Alzheimer’s disease medication.
Depression seems to predict cognitive impairment in many cases of Alzheimer’s disease. Dr. Rosenberg is using state-of-the-art PET imaging techniques to detect the earliest visible stages of Alzheimer’s disease. A PET scan shows amyloid plaques in the brain.
Brain damage caused by Alzheimer’s disease appears to be reversible in mice, although human trials are a long way off. When their dementia-causing genes were deactivated, genetically altered mice regained the ability to navigate mazes. Researchers hope memory might return if defective genes could be turned off, despite the plaques and protein tangles that are hallmarks of Alzheimer’s. Dr. Rosenberg is targeting different forms of amyloid and the “downstream” effects of amyloid in the brain.