Alzheimer’s disease: How it develops and reasons for hope

Alzheimer’s disease (AD) is a brain disorder that most often affects the elderly and whose main characteristic is the gradual but irreversible loss of memory. Personality changes often occur as well. Needless to say, the social, personal, economic, and emotional impact that affects both the individuals with AD and those who care for them is enormous. AD has affected both my own mother and my late mother-in-law, so I am no stranger to the issues that families face when caring for a member with the disease.

Causes of AD
The underlying causes and biology of AD have undergone intensive research, which may lead to clues for improved treatment. Such treatments are urgently needed, as an estimated 4 million people in the United States are affected by this devastating disease.

One of the culprits that is thought to lead to the disease is a chemical called beta amyloid. This chemical, which can be manufactured by many cells in the body, is composed of approximately 40 to 42 amino acids (the building blocks of cells and proteins) and seems to be a waste product of various biochemical reactions of the body. The problem occurs when the beta amyloid molecules meet other beta amyloid molecules and these accumulations get deposited on the surface of brain cells, rather than getting normally transported away from the brain. These deposits, called amyloid plaques, tend to accumulate in one area of the brain, called the hippocampus. The hippocampus is largely responsible for memory and certain processes that relate to the formation of thoughts.

While the deposit of amyloid material can be harmless if it occurs in other organs, a series of unfortunate events occur when the beta amyloid gets deposited on the brain cells of the hippocampus. A destruction of these cells occurs, and with this comes a loss of memory and brain tissue in this specific area of the brain. There may also be some associated damage to the blood vessels that supply areas of the brain with oxygen and nutrients.

While the only direct way to tell if there are deposits of amyloid on the cells of the brain is to perform a brain biopsy, there are fortunately a series of diagnostic tests that can help determine if there is an abnormality of the hippocampus caused by amyloid. These include magnetic resonance imaging (MRI) scanning, computerized tomography (CT) scanning, and a newer test called Positron Emission Tomography (PET) scanning. These tests, coupled with some rather simple tests of mental function, and a clinical history of memory loss and personality changes, can help health care professionals say with 80% certainty whether a patient has AD. While these tests aren’t perfect, they are better than resorting to a risky brain biopsy.

Treatments being researched
This better understanding of the chemical reactions that cause the amyloid to do its damage is cause for great excitement. Drugs are being developed that may help prevent the amyloid molecules from depositing on the brain cells. Vaccines are under development to prevent amyloid from damaging nerve cells of the brain. Still other testing has pointed to certain genetic abnormalities that allow a patient to form more amyloid, and thus opening the door to finding methods to decrease this production abnormality. These are all promising avenues for research. While amyloid is thought to be one of the more important chemicals leading to AD, other chemicals (including one called tau) have also been implicated and are under intensive research as well.

Currently available treatments
For now, we are left with the currently available and modestly effective treatments for established AD. Examples include tacrine (Cognex) and donepezil (Aricept). These help the remaining brain cells to function more effectively.

Is Alzheimer’s disease reversible?
It was once thought that certain diseases, such as atherosclerosis or hardening of the arteries (which cause heart attacks and strokes), were irreversible, that once they occurred, they could never improve. We now know that drug therapy and lifestyle modifications can reverse atherosclerosis. I maintain hope that AD, too, may one day prove to be a reversible process. I believe my hope is justified by our improved understanding of why this disease develops and by the novel treatments based on this knowledge.

Do you know someone who has Alzheimer’s disease? What treatments were helpful? Do you have questions about current or future treatments for this disease?

Alzheimer’s Disease
About 4.5 million Americans have Alzheimer’s disease. It is the seventh leading cause of death in the United States, and it is bound to become more common as the vanguard of the baby boom generation turns 65, the age at which Alzheimer’s becomes a major risk. A Guide to Alzheimer’s Disease is a special health report from Harvard Medical School that provides information for family members and caregivers, as well as for the individuals with Alzheimer’s, including getting financial and legal documents in order, investigating long-term care options, and determining what services are covered by health insurance and Medicare.

------------------------------------------------------------------------------------------------------------

Click here to join the group Harvard Med: Talking About Health on Gather

This content is not intended to substitute for personalized medical advice, diagnosis, or treatment from your healthcare provider. Read our full disclaimer.