Progressive Stages of Alzheimer's Disease

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Learn about the different stages of Alzheimer's Disease and memory and behavioral changes that occur as Alzheimer's Disease progresses.

Alzheimer's disease can take between 8 and 20 years to run its course. Experts have documented common patterns of symptom progression that occur in many individuals with Alzheimer's disease and developed several methods of "staging" based on these patterns. Progression of symptoms corresponds in a general way to the underlying nerve cell degeneration that takes place in Alzheimer's disease. Nerve cell damage typically begins with cells involved in learning and memory and gradually spreads to cells that control every aspect of thinking, judgment, and behavior. The damage eventually affects cells that control and coordinate movement.

Staging systems provide useful frames of reference for understanding how the disease may unfold and for making future plans. But it is important to note that all stages are artificial benchmarks in a continuous process that can vary greatly from one person to another. Not everyone will experience every symptom and symptoms may occur at different times in different individuals. People with Alzheimer's live an average of 8 years after diagnosis, but may survive anywhere from 3 to 20 years.

The framework for this section is a system that outlines key symptoms characterizing seven stages ranging from unimpaired function to very severe cognitive decline. This framework is based on a system developed by Barry Reisberg, M.D., Clinical Director of the New York University School of Medicine's Silberstein Aging and Dementia Research Center.

Within this framework, we have noted which stages correspond to the widely used concepts of mild, moderate, moderately severe, and severe Alzheimer's disease. We have also noted which stages fall within the more general divisions of early-stage, mid-stage, and late-stage categories.

Alzheimer's Stage 1:

No impairment (normal function)

Unimpaired individuals experience no memory problems and none are evident to a health care professional during a medical interview.

Alzheimer's Stage 2:

Very mild cognitive decline (may be normal age-related changes or earliest signs of Alzheimer's disease)

Individuals may feel as if they have memory lapses, especially in forgetting familiar words or names or the location of keys, eyeglasses or other everyday objects. But these problems are not evident during a medical examination or apparent to friends, family or co-workers.

Alzheimer's Stage 3:

Mild cognitive decline
Early-stage Alzheimer's can be diagnosed in some, but not all, individuals with these symptoms

Friends, family or co-workers begin to notice deficiencies. Problems with memory or concentration may be measurable in clinical testing or discernible during a detailed medical interview. Common difficulties include:

Word- or name-finding problems noticeable to family or close associates
Decreased ability to remember names when introduced to new people
Performance issues in social or work settings noticeable to family, friends or co-workers
Reading a passage and retaining little material
Losing or misplacing a valuable object
Decline in ability to plan or organize

Alzheimer's Stage 4:

Moderate cognitive decline
(Mild or early-stage Alzheimer's disease)

At this stage, a careful medical interview detects clear-cut deficiencies in the following areas:

Decreased knowledge of recent occasions or current events
Impaired ability to perform challenging mental arithmetic-for example, to count backward from 100 by 7s
Decreased capacity to perform complex tasks, such as marketing, planning dinner for guests or paying bills and managing finances
Reduced memory of personal history
The affected individual may seem subdued and withdrawn, especially in socially or mentally challenging situations