Alzheimer's Disease

Alzheimer's Disease Prevalence

Between 4.9 and 5.6 million individuals have some form of Dementia in the United States*, based on current estimates. Because the diagnosis of Alzheimer's disease can now be based on clinical measurements of Alzheimer's specific biomarkers, along with imaging and clinical signs and symptoms, the true prevalence of Alzheimer's disease among all Dementias in the US remains unclear. Although prevalence data using multiple criteria are still emerging, current estimates suggest that Alzheimer's disease represents approximately 60% of the Dementia burden.

The underlying processes that cause Dementia represent a significant cause of mortality. In the US, estimates suggest that Dementia is the 6th leading cause of death in persons aged 65 or older. In the UK, Alzheimer's Disease and other Dementias were the leading cause of death in 2024, suggesting an increasing mortality risk in developed countries.

What Goes Wrong in Alzheimer's Disease?

Alzheimer's Disease is caused by a complex, progressive interplay of genetics, lifestyle, environment, and age-related brain changes that unfold over decades. While the exact trigger remains unknown, the disease is characterized by several hallmark brain changes and biological mechanisms.  

We know that the deposition and accumulation of fibrous proteins accompany irreversible brain damage. These insoluble proteins, called beta-amyloid, form plaques that disrupt cellular communication, alter how brain cells use energy, and promote cell death. The second hallmark of AD, also observed by Dr. Alois Alzheimer over 100 years ago under a microscope, is the neurofibrillary tangles of dead and dying neurons, composed of Tau, another brain protein. That's why medical professionals will often speak of the "plaques and tangles" of AD.

The result is a slow and progressive decline in memory, thinking, and reasoning skills. Eventually, people lose the ability to swallow and breathe in a coordinated fashion. Even in the absence of other diseases such as kidney failure and cancer, Alzheimer's Disease is a terminal illness.

What Are The Symptoms of Alzheimer's Disease?

Alzheimer's Disease comprises a spectrum rather than a defined set of signs and symptoms. Slow progression, rather than a sudden change, is often the key to differentiating Alzheimer's behaviors from those associated with other kinds of Dementia. Life expectancy after an Alzheimer's diagnosis can be anywhere from four to 20 years. People who have Dementia often die from other causes such as cancer, kidney failure, and cardiovascular disease.

The Alzheimer's Association lists the 10 warning signs of Alzheimer's Disease – the first of which is memory loss. After reading the list, you might think, "How are these behaviors different from what everybody does at one time or another?" The difference is the frequency and the ability to make self-corrections.

Healthcare providers often use staging to describe the progression and severity of diseases such as cancer, kidney failure, and Dementia. The following staging criteria will help you understand your loved one's condition and plan for future caregiving needs.

Mild or Early-stage Alzheimer's Disease

In this first stage, people experience memory loss, difficulty remembering newly learned information, and have trouble completing complex tasks such as planning a family event. Personality changes, such as uncharacteristic anger and increasing difficulty finding the right words, getting lost, or misplacing items, are other common signs. With help, your parent, spouse, or sibling in this stage may still be able to live independently.

Moderate or Mid-stage Alzheimer's Disease

During this phase, people may confuse family members with close friends, forget personal history details such as where they went to school or where they were born, and need help with dressing and personal hygiene. Some people may become restless, suspicious of others, and confrontational. At this stage, your relative will need close supervision and assistance during the day, and perhaps a caregiver at night.

Severe or Late-stage Alzheimer's Disease

In the final stage, people lose the ability to speak coherently and need help with eating, dressing, using the bathroom, and walking. Eventually, late-stage Alzheimer's patients lose the ability to swallow and control their bladder and bowels. During this final stage, your loved one will need 24-hour care, either at home or in a Dementia care facility.

For more information on Alzheimer's disease and how to manage care, please see the source material below and the related blog post, "Empowering Caregivers: Essential Tips for Supporting Individuals With Alzheimer's."

*Sources:

1. CDC.gov: All about Alzheimer's

2. JAMA Neurology 2025: US Burden of Disorders Affecting the Nervous System.

3. 2025 World Health Organization Factsheet: Dementia. 

4. National Institute on Aging: What Causes Alzheimer's Disease?

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