Understanding Alzheimer’s and its effects on the brain

Friday, November 22, 2024

[9 MIN READ]

In this article:

Alzheimer’s disease affects millions of Americans, and it’s the most common form of dementia.
The causes of Alzheimer’s disease likely include a combination of genetics and changes in the brain as we age, along with lifestyle factors that are well within our control.
New diagnostic tools and advancing treatment protocols offer new hope for earlier detection and the possibility of preventing Alzheimer’s and other types of dementia.

Understanding Alzheimer’s and its effects on the brain

Each patient’s journey with Alzheimer’s disease is unique, says Verna Porter, M.D., a neurologist and director at the Brain Health Center within Providence St. John’s Health Center in Santa Monica.

With 6 million Americans affected by the disease — and the fact that Alzheimer’s disease is the sixth-leading cause of death in the U.S. — it’s time we understood it better.

“The number of Americans with Alzheimer’s is predicted to double in the next two decades,” says Nancy Isenberg, M.D., MPH, a neurologist and Providence Swedish’s medical director of the Center for Healthy Aging. “Deaths related to a number of other diseases are being reduced, but deaths from Alzheimer’s are on the rise.”

What is Alzheimer’s disease?

Alzheimer’s is a brain disease that worsens over time. Cell damage causes complex changes in the brain that lead to dementia and other symptoms. According to the Alzheimer’s Association, the most common risk factor currently known for Alzheimer’s disease is increasing age. However, the disease is not a normal part of everyone’s aging process.

“Alzheimer’s disease is incredibly complex, but recent advances offer real potential for earlier diagnosis and more effective interventions,” says Dr. Porter. “The intersection of traditional medicine, cutting-edge research and holistic care provides a well-rounded framework for us to approach the disease thoughtfully and compassionately.”

Alzheimer’s disease vs. dementia

Dementia is defined as loss of cognitive function in two or more domains that affect our ability to function independently. Alzheimer’s disease is the leading cause of dementia, not the other way around.

“Dementia is an umbrella term, and there are many types and a range of causes of dementia,” explains Dr. Isenberg. “The brain is a critical organ for our ability to function in the world. Most people with dementia have a mixed type with neurodegenerative and vascular pathologies.”

Causes of Alzheimer’s

While it doesn’t have one specific genetic cause, Alzheimer’s has some genetic risk factors. Research shows that those with a parent or sibling with Alzheimer’s are more likely to develop the disease than those who don’t. When someone inherits an altered version of certain genes, which is rare, they are likely to develop Alzheimer’s before age 65, and some much earlier. But genes you inherit aren’t the only determining factor for the disease.

The causes likely include a combination of specific genes and changes in the brain as we age, along with lifestyle and environmental factors. The good news is that researchers now believe about 45% of factors contributing to Alzheimer’s are preventable: high blood pressure, smoking, physical inactivity, depression and social isolation, to name a few.

How Alzheimer’s affects the brain

Alzheimer’s develops as abnormal clumps of proteins — called amyloid and tau — build up in the brain. The accumulation of tau causes neurofibrillary tangles within cells, and amyloid plaque forms outside the cells. This buildup makes it harder for the brain to function. Advances in brain imaging techniques now allow neurologists to view these changes over time.

Biologically, the stages of Alzheimer’s are defined by the buildup of amyloid plaques, which accumulate first, and tau tangles, which continue to spread over time and neurodegeneration. These tiny biological changes in the brain have a huge impact and correlate with the decline in a person’s ability to function normally.

Scientists also are exploring very early steps in the disease’s development by detecting changes in the brain and body fluids years before the first symptoms can be seen. The goal is to understand precisely what causes Alzheimer’s, making early diagnosis easier.

“The neuropathological changes of Alzheimer’s disease accumulate over two decades before most people have clinical symptoms,” says Dr. Isenberg.

Alzheimer’s disease destroys neurons and their connections to one another, called synapses. Over time, the combination of issues causes the brain to shrink, called atrophy. Among other effects, some differences include:

Brain cells designed to clear waste no longer work properly
Communication is blocked by amyloid plaque
Inflammation and lack of proper oxygen damages neurons

Brain areas impacted and disease progression

The early stages of Alzheimer’s primarily affect the median temporal lobe, which is key to learning, forming memories and navigating the space around us. That explains the early memory loss and disorientation in most Alzheimer’s patients.

As the disease progresses, other regions of the brain are involved. The temporal lobes affect language and recognition, and the parietal lobes affect spatial awareness. The frontal lobes impact decision-making, behavior and personality.

“Late stages of Alzheimer’s show widespread brain atrophy, severely affecting nearly all cognitive and functional areas, including behavior,” says Dr. Porter. “Alzheimer’s is emotionally draining for both patients and caregivers. Watching someone slowly lose their independence is heart-wrenching.”

Diagnosing Alzheimer’s disease

There is no single test that can determine if a person has Alzheimer’s or another dementia. And even if test results show a genetic factor or specific changes in the brain, that doesn’t mean the person will develop Alzheimer’s.

Physicians combine medical history and details from neurological exams, functional and cognitive assessments. And they have a number of other tools for diagnosing and staging the disease:

Imaging — MRI, CT, Amyloid PET scans and tau PET scans
Cerebrospinal fluid (CSF) analysis — measurements of beta-amyloid and tau levels
Blood tests — an emerging way to identify biomarkers for the disease

New blood tests aim to detect Alzheimer’s years before symptoms begin. These tests look for high levels of tau proteins in the blood. Clinical trials show that they may be highly accurate in diagnosing Alzheimer’s disease, and bloodwork is much less invasive than other testing. Researchers also are investigating new cognitive screenings to identify Alzheimer’s and dementia as early as possible.

“The p-tau217 blood test is a promising tool for early detection of Alzheimer’s, reflecting tau pathology in the brain. It’s gaining traction as a less invasive alternative to CSF analysis, but it is not yet fully mainstream,” explains Dr. Porter, who says the accuracy may be better than CSF tau measures and amyloid PET imaging. This blood test is useful in research, but it’s still more of a predictive tool than a definitive way to diagnose Alzheimer’s disease.

“Advances like the p-tau217 blood test could eventually transform diagnostic practices. These tests promise earlier diagnosis, potentially allowing interventions to slow progression before symptoms manifest,” she continues. “The latest Alzheimer’s drugs like monoclonal antibodies offer hope as well, but they have side effects and high costs.”

Symptoms of Alzheimer’s

Many people with Alzheimer’s follow a similar path of symptoms beginning with mild cognitive impairment, memory loss, along with poor judgment and decision-making skills. “People who ultimately develop Alzheimer’s disease often have challenging symptoms that precede their dementia,” Dr. Isenberg says.

Over time, symptoms may include:

Losing keys, wallet, phone
Difficulty keeping track of time or place
Trouble handling money or paying bills
Mood or personality changes
Depression, anxiety or emotional outbursts
Trouble reading, writing or sleeping
Inappropriate behaviors, such as wandering or being overly familiar with strangers

Eventually, cell damage from Alzheimer’s disease affects daily life by preventing a person from performing basic functions like getting dressed, speaking, walking and swallowing.

“People can live well with Alzheimer’s disease and related dementias,” says Dr. Isenberg. “Through a strengths and team-based approach, focusing on patient and care partner education, engagement and support, there are all sorts of ways to scaffold or preserve areas of functioning and importantly quality of life.”

Alzheimer’s treatments and research

“Families often look for a cure, but the best we currently can offer are treatments that slow disease progression,” says Dr. Porter, who explains that, while there isn’t yet a cure, research and new understanding about risk factors and the ability to make lifestyle changes offer new hope.

“Alzheimer’s is often a disease of slow decline, so maintaining hope while also preparing families for what lies ahead is crucial. I help families balance optimism — especially when new treatments emerge — with a realistic understanding of the disease’s progression and the limitations, risks and benefits of emerging therapies,” says Dr. Porter. “While slowing the disease is a primary goal, quality of life remains at the forefront.”

Current treatments

Current treatments for Alzheimer’s disease include:

Monoclonal antibodies to slow cognitive decline
Cholinesterase inhibitors to manage symptoms
N-methyl-D-aspartate (NMDA) receptor antagonists to treat memory loss in advanced stages
Long-term residential care, when needed

“While medications don’t halt disease progression, they help manage symptoms and improve quality of life,” says Dr. Porter, who emphasizes there are experimental therapies, such as anti-tau therapies to prevent tau accumulation and anti-inflammatory drugs. Gene therapies also are being explored for those with a genetic marker.

Early diagnosis is key for dementia and Alzheimer’s disease since lifestyle factors can increase your risk. The risk — along with progression of the disease for those who have it — can be impacted by these lifestyle changes:

Quitting smoking
Increasing physical activity
Controlling blood pressure
Eating a healthy diet
Staying socially active
Drinking less alcohol
Treating depression

Neurologists at Providence use individualized approaches — combining traditional therapies, lifestyle changes and other emerging methods — to treat the whole person, not just the disease. And they consider factors that can slow its progression.

“For many patients, addressing spiritual well-being can improve emotional health and mental clarity, which complements medical and lifestyle interventions,” Dr. Porter says. “This spiritual aspect can help patients maintain a sense of purpose during cognitive decline. Spiritual care also can offer comfort to caregivers and family members coping with the emotional weight of the disease.”

Emphasizing that the Center for Healthy Aging is committed to improving access and care to those facing disproportionate risk, namely women, Dr. Isenberg says, “Thankfully 45% of cases of dementia are preventable over the lifespan. This knowledge is very powerful.”

Dr. Porter agrees. “Sleep and stress management are often overlooked but crucial to brain health. Cognitive health needs a holistic approach, beyond the brain alone,” she says. “Neurologists can’t work in isolation when managing Alzheimer’s. We collaborate with geriatricians, psychiatrists, neuropsychologists, dietitians, physical therapists and social workers to address all aspects of the patient’s life.”

Research and future hope for families

Recent clinical studies focus on gene therapy targeting specific carriers that serve as a major risk factor for Alzheimer’s. Investigation of anti-inflammatory pathways — using drugs that stimulate an immune response — is ongoing and shows potential in early trials.

“The combination of cognitive stimulation and physical exercise is gaining recognition for its neuroprotective effects in Alzheimer’s patients. This is a particular focus for the Pacific Brain Health Center of the Pacific Neuroscience Institute,” says Dr. Porter. “The future of Alzheimer’s treatment will likely involve precision medicine, where genetic, biomarker and lifestyle data inform personalized treatment plans,” says Dr. Porter. “This approach could help us understand why some patients progress more rapidly than others, and how certain lifestyle changes might alter the disease trajectory.”

Aging well

“Our choices, environment and how we live our days, the quality of care we receive, our community— these all impact our current self and our future self in terms of our brain health risks and resilience.”

If you or a loved one is beginning to show signs of Alzheimer’s disease or other dementias, neurologists at Providence are here for you. Even without symptoms — and no matter your age — talk with your primary care doctor about risk factors and getting help with lifestyle changes to protect your brain health.

Contributing caregivers

Verna Porter, M.D., is a neurologist and director of Programs for Alzheimer’s Disease, Dementia and Neurocognitive Disorders at the Pacific Neuroscience Institute’s Brain Health Center.

Nancy Isenberg, M.D., MPH, is a neurologist and medical director of the Center for Healthy Aging and the Women’s Brain Program at Providence Swedish.

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