From 2013 to 2020, yearly spending on Alzheimer’s disease research quintupled, skyrocketing from $504 million to $2.683 billion. Research into what causes Alzheimer’s is only projected to increase; by 2022, spending on Alzheimer’s research is estimated to reach $3.079 billion. This fatal, incurable disease affects about 5.8 million people, according to the Mayo Clinic, and greatly affects their quality of life. Researchers and institutions are scrambling to uncover the science of Alzheimer’s — to find causes for the disease, treatments and possibly even a cure as the number of people who have the disease continues to increase.

It’s a startlingly common age-related condition that begins with forgetfulness and progresses over time to a decline in the ability to function and respond to one’s environment. But while Alzheimer’s is primarily a disease that affects the over-65 population, younger people can be diagnosed with it as well. Early-onset Alzheimer’s can affect people in their 30s, 40s and 50s. This article will look at what causes Alzheimer’s and examine the science of Alzheimer’s, what actually happens in the brain when a person is suffering from the disease, and possible treatments.

What Is Alzheimer’s Disease?

Alzheimer’s disease is a type of dementia, and according to the Centers for Disease Control and Prevention, it’s the most common kind. The condition affects the areas of the brain that control language, memory and thought. There’s no cure for the disease, and treatments are currently limited. Unfortunately, Alzheimer’s is ultimately fatal.

How Is Alzheimer’s Different From Dementia?

While people often refer to Alzheimer’s and dementia interchangeably, they aren’t the same. Alzheimer’s encompasses 60% to 80% of dementia cases, but there are other kinds of dementia unrelated to Alzheimer’s, including vascular dementia (which can be caused by high blood pressure), dementia with Lewy bodies and Cruetzfeldt-Jakob disease (which are each tied to proteins), alcohol-related dementia, and other cognitive issues that can accompany medical conditions like Parkinson’s or HIV/AIDS.

What Causes Alzheimer’s Disease?

Scientists and physicians aren’t exactly sure what causes Alzheimer’s, but there are several risk factors. Age is the most common as well as a genetic history of the disease within one’s family. A healthy lifestyle can reduce the risk, but it’s not clear by how much.

What Happens in the Brain During Alzheimer’s Disease?

What we do know is that changes in the brain can occur years before a person starts outwardly showing symptoms. The brain is composed of billions of neurons that transmit chemical and electric signals to one another — it’s a vital part of how our brain functions. Alzheimer’s disease is the disruption of communication between these brain cells. As a result, these cells wither and die. While we can grow new brain cells, dying neurons lose the ability to repair and replace themselves.

According to the National Institutes of Health, the first areas affected by Alzheimer’s are the centers of the brain where memory functions are located, which is why memory loss is one of the first outward symptoms of the disease. Eventually, though, it disrupts many other areas of the brain. While brain shrinkage is a common result of aging, Alzheimer’s causes brain atrophy as a result of neuron death. This results in a marked loss of volume in the brain.

When the brain tissue of an Alzheimer’s patient is examined postmortem, there are certain characteristics present; the problem is scientists aren’t sure whether these issues cause Alzheimer’s or are a result of it.

Toxic Proteins Accumulate and Disrupt Neurons

According to the Alzheimer’s Association, beta-amyloid is a protein piece that may be associated with neuron disruption and eventual death. It’s possible there are flaws in the production and disposal of beta-amyloid, a fragment of the larger amyloid precursor protein, that causes it to build up in a toxic manner and disrupt the connection between brain cells. When this compound accumulates, it’s called beta-amyloid plaque. This buildup can be seen in the brains of Alzheimer’s patients.

Neurofibrillary Tangles Inhibit Neurons

Scientists and doctors also see neurofibrillary tangles in the brains of patients who have died of Alzheimer’s. Neurons have a protein called tau within them that stabilizes internal cell pathways. But in Alzheimer’s patients, tau doesn’t do its job properly. Instead, these molecules clump together, which causes neurofibrillary tangles inside the neurons. This, along with beta-amyloid plaque, blocks communication between neurons. It’s important to note that reduced blood flow can contribute to the buildup of high tau.

Brain Inflammation Harms Cells

Another characteristic of Alzheimer’s patients’ brains is inflammation. Many drug trials have focused on eliminating the two proteins, beta-amyloid and tau, as a possible treatment for the disease and come up short. This has led scientists to believe there may be an alternate issue at work: inflammation of the brain. It may occur because the brain’s immune system isn’t operating correctly — whether due to a virus or aging-related stress. This can cause neurons to die in large swaths.

Promising Treatments

There is currently no cure for Alzheimer’s nor are there treatments to halt its progress. Most treatments simply address the symptoms of memory loss, and even those are temporary. But there are promising new leads on the horizon.

One recent study published in Nature Aging found that sildenafil, commonly known as Viagra, can reduce the risk of deveoping Alzheimer’s disease by almost 70% because it increases neuron growth and reduces tau plaque. However, more studies are needed to determine causality.

Another recent experimental treatment looked at blocking beta-amyloid plaque before it built up rather than treating it after the fact (which has not yielded positive results). According to the BBC, mice in the trials showed improved memory and cognitive ability after receiving the treatment.

Protollin is a nasal vaccine that recently entered human trials. According to Business Insider, it can be preventative or administered to slow the progression of Alzheimer’s. It works by activating brain cells to remove beta-amyloid plaque.

Advances in Alzheimer’s research take time, to be sure, but these promising new treatments — along with many others on the horizon — hopefully will result in an eventual cure for Alzheimer’s disease.

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