Alzheimer’s Disease, as defined in medical journals, is caused by the abnormal build-up of proteins in and around brain cells.
One of the proteins involved is called amyloid, deposits of which form plaques around brain cells.
The other protein is called tau, deposits of which form tangles within brain cells.
As Alzheimer's disease progresses, people experience greater memory loss and other cognitive difficulties.
Problems can include wandering and getting lost, trouble handling money and paying bills, repeating questions, taking longer to complete normal daily tasks, and personality and behavior changes.
Most people with Alzheimer's are 65 years of age and older. One in 10 people, aged 65 or more, has Alzheimer's.
After the age of 65, the risk doubles every five years. Age, family history, genetics, chemical exposure, infections, and other factors play a role in who gets Alzheimer's.
The brain has 100 billion nerve cells (neurons). Each nerve cell connects with many others to form communication networks. Groups of nerve cells have special jobs. Some are involved in thinking, learning, and remembering. Others help us see, hear and smell.
The most common early symptom of Alzheimer's is difficulty remembering newly learned information.
Just like the rest of our bodies, our brains change as we age. Most of us eventually notice some slowed thinking and occasional problems with remembering certain things. However, serious memory loss, confusion and other major changes in the way our minds work may be a sign that brain cells are failing.
To do their work, brain cells operate like tiny factories. They receive supplies, generate energy, construct equipment and get rid of waste.
Cells also process and store information and communicate with other cells. Keeping everything running requires coordination and large amounts of fuel and oxygen.
Scientists believe Alzheimer's disease prevents parts of a cell's factory from running well. They are not sure where the trouble starts.
But just like a real factory, back-ups and breakdowns in one system cause problems in other areas. As damage spreads, cells lose their ability to do their jobs and, eventually die, causing irreversible changes in the brain.
Mild Alzheimer’s disease includes memory problems and cognitive difficulties that may include: 1) taking longer than usual to perform daily tasks; 2) difficulty handling money or paying the bills; 3) wandering and getting lost; 4) experiencing personality and behavior changes, such as getting upset or angry more easily, 5) hiding things or 6) pacing.
Moderate Alzheimer’s disease is when the parts of the brain responsible for language, senses, reasoning, and consciousness are damaged. Symptoms include: 1) greater memory loss and confusion; 2) difficulty recognizing friends or family; 3) an inability to learn new things; 4) difficulty performing tasks with several stages, such as getting dressed; 5) difficulty coping with new situations; 6) impulsive behavior and 7) hallucinations, delusions, or paranoia.
In severe Alzheimer’s disease, plaques and tangles are present throughout the brain, causing the brain tissue to shrink substantially. This can lead to: 1) an inability to communicate; 2) dependency on others for care and 4) being unable to leave bed all or most of the time.
Although age is the main risk factor for Alzheimer’s disease, this is not just a condition that affects older adults. According to the Alzheimer’s Association, early onset Alzheimer’s disease affects around 200,000 U.S. adults under the age of 65 years. Many people with this condition are in their 40s or 50s.
Plaques and tangles
Two abnormal structures called plaques and tangles are prime suspects in damaging and killing nerve cells. Plaques are deposits of a protein fragment called beta-amyloid that build up in the spaces between nerve cells.
Tangles are twisted fibers of another protein called tau that build up inside cells. Though autopsy studies show that most people develop some plaques and tangles as they age, those with Alzheimer’s tend to develop far more and in a predictable pattern, beginning in the areas important for memory before spreading to other regions.
While scientists are not sure what role plaques and tangles play in Alzheimer's disease, experts believe they are crucial in blocking communication among nerve cells and disrupting processes that cells need to survive. The destruction and death of nerve cells causes memory failure, personality changes, problems carrying out daily activities and other symptoms of Alzheimer's disease
Alzheimer's, a progressive disease, worsens over time, where dementia symptoms gradually worsen through the years. In its early stages, memory loss is mild, but with late-stage Alzheimer's, individuals lose the ability to carry on a conversation and respond to their environment.
Alzheimer's is the sixth-leading cause of death in the United States. On average, a person with Alzheimer's lives 4 to 8 years after diagnosis but can survive for 20 years, depending on other factors.
Though there is yet no cure for Alzheimer’s, one treatment — aducanumab (Aduhelm) — is the first therapy being tried that demonstrates that removing amyloid from the brain is reasonably likely to reduce cognitive and functional decline in people living with early Alzheimer’s.
Others can temporarily slow the worsening of dementia symptoms and improve quality of life for those with Alzheimer's and their caregivers. Today, there is a worldwide effort underway to find better ways to treat the disease, delay its onset and prevent it from developing.
Early this month, the US Food and Drug Administration said Aduhelm can only be given to patients with mild dementia after facing intense backlash from many in the medical community over its authorization.
Biogen's Aduhelm received an "accelerated approval" by the FDA in June, despite an independent expert panel advising the agency that it found insufficient evidence of its benefit.
"Since the agency approved Aduhelm, prescribers and other stakeholders have expressed confusion regarding the intended population for treatment," FDA spokesman Michael Felberbaum said in a statement sent to AFP.
"It was important to clarify the intent of currently approved labeling for prescribers; specifically, that it is appropriate to initiate treatment in patients with the mild cognitive impairment or mild dementia stages of Alzheimer's disease, which is consistent with the patient population studied in clinical trials,” he added.
While it doesn't stop physicians prescribing Aduhelm to patients in more advanced stages of the disease, it is a notable reversal.
Aduhelm, an intravenously infused monoclonal antibody, also known by its generic name aducanumab, was tested in two late-stage human trials, known as Phase 3 trials.
It convincingly showed a reduction in the build-up of beta amyloid proteins, that create a plaque in the brain tissue of Alzheimer's patients.
But whether this correlated with a reduction in cognitive decline is not certain -- one study suggested it did, while the other did not.
As a result, many experts reacted with dismay at Aduhelm's approval, and at least three of the 11-member independent committee that voted unanimously against recommending the drug to the FDA subsequently resigned.
Beyond the false hope it might offer for patients and loved ones, Aduhelm's whopping price tag of $56,000 a year could cost Medicare, the federally insurance program for elderly Americans, tens of billions of dollars a year, experts argued.
"With Alzheimer's disease affecting six million Americans, the financial and human implications of the approval are staggering," wrote Vinay Prasad, an associate professor of medicine at the University of California San Francisco, in an op-ed in Medpage Today.
The Alzheimer's Association reacted positively to Thursday's announcement.
"We appreciate the FDA's thoughtful consideration and response to the Alzheimer's Association and others in the community including physicians, researchers and patients to ensure this treatment is prescribed only to those who may see benefit," the group said.