Alzheimer’s disease is a progressive brain disorder that gradually destroys memory, thinking skills, and the ability to carry out daily activities. It is the most common cause of dementia — a general term for a decline in cognitive function severe enough to interfere with daily life — and accounts for 60 to 80 percent of all dementia cases.
Alzheimer’s disease is not a normal part of aging. While age is the greatest known risk factor most people with Alzheimer’s are 65 or older and the disease is not an inevitable consequence of growing older. Understanding what Alzheimer’s disease is, how it progresses, and what resources are available can help affected individuals and their families navigate this challenging condition with greater confidence and support.
How common is Alzheimer’s disease
Alzheimer’s disease affects millions of Americans and its prevalence is growing as the population ages. Key statistics include:
- More than 6 million Americans are currently living with Alzheimer’s disease
- The number of people with Alzheimer’s is projected to nearly triple by 2050 as baby boomers age
- Alzheimer’s disease is the seventh leading cause of death in the United States
- Two thirds of Americans with Alzheimer’s are women
- More than 11 million Americans provide unpaid care for people with Alzheimer’s and other dementias
What causes Alzheimer’s disease
The exact causes of Alzheimer’s disease are not fully understood but researchers believe it results from a combination of genetic, lifestyle, and environmental factors that affect the brain over time. Key factors include:
- Age — the greatest known risk factor. The risk of Alzheimer’s doubles approximately every five years after age 65.
- Genetics — having a first degree relative such as a parent or sibling with Alzheimer’s increases the risk. A specific gene called APOE e4 is associated with a higher risk of developing Alzheimer’s though carrying this gene does not mean a person will definitely develop the disease.
- Early onset Alzheimer’s — in rare cases Alzheimer’s disease develops before age 65 often in people in their 40s or 50s. Early onset Alzheimer’s is frequently linked to specific genetic mutations.
- Cardiovascular risk factors — conditions that affect the heart and blood vessels including high blood pressure, high cholesterol, diabetes, and obesity are associated with an increased risk of Alzheimer’s
- Head trauma — a history of serious head injuries may increase the risk of Alzheimer’s disease
- Lifestyle factors — physical inactivity, social isolation, and lower levels of education are associated with higher risk while physical activity, social engagement, and cognitive stimulation may be protective
How Alzheimer’s disease affects the brain
Alzheimer’s disease causes changes in the brain that begin years or even decades before symptoms appear. Key brain changes include:
- Amyloid plaques — abnormal clumps of protein fragments called beta-amyloid that accumulate between nerve cells in the brain disrupting communication between neurons
- Tau tangles — twisted fibers of another protein called tau that build up inside nerve cells interfering with the transport of nutrients and other essential materials within the cell
- Neuronal death — as the disease progresses nerve cells die and brain tissue shrinks. Different regions of the brain are affected at different stages of the disease.
Stages of Alzheimer’s disease
Alzheimer’s disease typically progresses through several stages though the pace and specific symptoms vary significantly from person to person:
Early stage — mild Alzheimer’s In the early stage a person may function independently but begins to experience noticeable memory lapses especially for recent events. Common symptoms include:
- Forgetting names or appointments and not remembering them later
- Difficulty finding the right word in conversation
- Misplacing objects
- Difficulty with planning or problem solving
- Getting lost in familiar places
- Personality changes such as increased anxiety or depression
Middle stage — moderate Alzheimer’s The middle stage is typically the longest stage and may last many years. Cognitive decline becomes more pronounced and the person requires more assistance with daily activities. Common symptoms include:
- Increasing memory loss and confusion
- Difficulty recognizing family members and friends
- Inability to learn new things or recall personal history
- Difficulty with activities of daily living such as dressing and bathing
- Wandering and getting lost
- Sleep disturbances
- Behavioral and personality changes including suspicion, agitation, and depression
- Bowel and bladder problems
Late stage — severe Alzheimer’s In the late stage a person loses the ability to respond to their environment, carry on a conversation, and eventually to control movement. They require full-time care. Common features include:
- Loss of awareness of recent experiences and surroundings
- Difficulty swallowing and eating
- Increased vulnerability to infections especially pneumonia
- Loss of mobility
- Inability to communicate verbally
Diagnosis of Alzheimer’s disease
There is no single test to diagnose Alzheimer’s disease. Diagnosis involves a comprehensive evaluation including:
- Medical history and physical examination
- Neurological examination to assess memory, problem solving, attention, language, and coordination
- Cognitive and neuropsychological testing
- Brain imaging such as MRI or CT scans to rule out other causes of symptoms
- Blood tests to rule out other conditions
- In some cases cerebrospinal fluid analysis or PET scan imaging of amyloid or tau in the brain
A definitive diagnosis of Alzheimer’s disease can only be confirmed after death through examination of brain tissue. During a person’s lifetime the diagnosis is based on clinical assessment and is described as probable or possible Alzheimer’s disease.
Treatment of Alzheimer’s disease
There is currently no cure for Alzheimer’s disease. Treatment focuses on managing symptoms and slowing progression where possible:
- Medications for cognitive symptoms — several FDA-approved medications can temporarily improve or stabilize cognitive symptoms in some people with Alzheimer’s including cholinesterase inhibitors such as donepezil, rivastigmine, and galantamine and the NMDA receptor antagonist memantine
- Newer disease-modifying treatments — the FDA has approved several new medications including lecanemab and donanemab that target amyloid plaques and have been shown to slow the progression of early Alzheimer’s disease in clinical trials. These represent a significant advance in treatment though they are not cures and are associated with potential serious side effects.
- Medications for behavioral symptoms — medications may be used to manage behavioral symptoms such as depression, anxiety, sleep disturbances, and agitation though they are used cautiously due to potential side effects in older adults
- Non-pharmacological approaches — structured activities, music therapy, physical exercise, social engagement, and caregiver education and support are important components of comprehensive Alzheimer’s care
Caring for someone with Alzheimer’s disease
Caring for a person with Alzheimer’s disease is one of the most demanding caregiving roles. Key resources for caregivers include:
- Alzheimer’s Association — alz.org provides comprehensive information, support groups, a 24-hour helpline at 1-800-272-3900, and a Care Consultation service
- Alzheimer’s Foundation of America — alzfdn.org provides educational resources and support for people affected by Alzheimer’s disease
- Area Agency on Aging — local AAAs can connect caregivers with respite care, caregiver support groups, and other community resources
- National Institute on Aging — nia.nih.gov provides research-based information about Alzheimer’s disease and related dementias
Planning ahead
A diagnosis of Alzheimer’s disease makes advance planning especially urgent. While the person with Alzheimer’s still has the capacity to participate in decision making it is important to:
- Complete legal documents including a durable power of attorney, healthcare power of attorney, and advance directive
- Discuss wishes regarding future care and end of life preferences
- Review financial accounts and beneficiary designations
- Consult with an elder law attorney about long term care planning and Medicaid eligibility
- Consider safety modifications to the home
Key terms to know
- Alzheimer’s disease — a progressive brain disorder that destroys memory and cognitive function
- Dementia — a general term for a decline in cognitive function severe enough to interfere with daily life
- Amyloid plaques — abnormal protein deposits that accumulate between nerve cells in the brains of people with Alzheimer’s
- Tau tangles — twisted protein fibers that build up inside nerve cells in Alzheimer’s disease
- APOE e4 — a gene variant associated with increased risk of Alzheimer’s disease
- Early onset Alzheimer’s — Alzheimer’s disease that develops before age 65
- Cholinesterase inhibitor — a class of medications used to treat cognitive symptoms of Alzheimer’s disease
- Disease-modifying treatment — a treatment that targets the underlying disease process rather than just managing symptoms
Sources
- Alzheimer’s Association — alz.org
- National Institute on Aging — nia.nih.gov
- Centers for Disease Control and Prevention — CDC
- Alzheimer’s Foundation of America — alzfdn.org
This article is for general informational purposes only and does not constitute legal or medical advice. Consult a licensed healthcare provider for guidance specific to your situation.