HBOThe Alzheimer's Project

• Home
• About the Project
• Watch the Films
• Alzheimer's Basics
• Hope in Science
• National Impact
• Get Help
• Get Involved

The Stages of Alzheimer's Disease

Though the time from diagnosis to death differs among people with Alzheimer's disease, the disease generally progresses through the same stages.

Dr. Ron Petersen was the first to define a condition called mild cognitive impairment (MCI) to describe early changes in memory. Dr. Petersen defined MCI as a condition in which a person has memory problems greater than expected for a person that age, but who does not have the other cognitive or personality changes that typically accompany AD. People with MCI are an important group for researchers to understand because about 80 percent of people with MCI characterized by memory loss go on to develop AD within seven years. (In contrast, only from 1 to 3 percent of people older than sixty-five with healthy cognitive abilities will develop AD in any given year.)

The definition and description of MCI has been a big advance because it provides a framework in which experienced clinicians, using sophisticated neuroimaging techniques and sensitive memory and cognitive tests, can monitor a person's cognitive changes over time. Being able to characterize and track cognitive changes is critical to determining whether a person has AD and when treatment may be most effective.

Over time, as the plaques and tangles continue to proliferate, an individual with MCI may progress to a clinical diagnosis of Alzheimer's disease. This stage is called mild, or early, Alzheimer's disease. More of the cerebral cortex will be affected so memory loss will increase, and other cognitive abilities will diminish. An individual with mild AD may get lost in familiar places or fail to recognize his surroundings. He may take longer to accomplish the daily tasks of living like washing, dressing, and eating. He may have trouble handling money or paying bills or exercise poor judgment. Mood and personality changes can also occur; he may lose spontaneity or drive, or show increased anxiety or aggression. Although a person with mild AD may still seem healthy, it will be harder for him to make sense of his world. Although the individual and his family members and friends may have been aware of troubling changes for some time, AD is often diagnosed during this phase. The diagnosis often helps families make sense of their loved one's behaviors.

As Alzheimer's disease progresses and the damage spreads further in the brain, the person enters a stage referred to as moderate Alzheimer's disease. The brain continues to shrink and symptoms become more pronounced as the disease reaches the areas of the cerebral cortex that control language, reasoning, sensory processing, and conscious thought. A person with moderate AD may wander or become confused, anxious or agitated, engaging in angry outbursts, tearfulness, irritability or restlessness. His attention span may shorten. He may have problems recognizing family and friends, and difficulty with language, reading, writing, and arithmetic, and with the logical organization of thoughts. He may be unable to learn new things and consequently be unable to cope with new situations. At this stage, a person with AD might also experience hallucinations and paranoid delusions, and lose impulse control, leading to things like inappropriate undressing or the use of vulgar language. It is helpful for caregivers to understand the disease and to be more prepared for these sorts of behaviors before they happen, and to know that it is the disease that is causing them.

A person with moderate AD may be unable to carry out activities that require him to follow a sequence, like getting dressed or setting the table. Anger may mask anxiety and confusion. According to the National Institute on Aging, a person at the moderate stage of AD "may angrily refuse to take a bath or get dressed because he does not understand what his caregiver has asked him to do. If he does understand, he may not remember how to do it."

At the last stage of this illness, severe Alzheimer's disease, plaques and tangles are found throughout the brain. Most areas have shrunken further, leaving only a thin ribbon of gray matter and even larger fluid-filled ventricles. An individual at this final stage cannot communicate in any way except moaning and grunting. He doesn't recognize loved ones and is completely dependent on others for care. He may experience weight loss and difficulty swallowing, seizures, skin infections, lack of bladder and bowel control, and increased sleeping. If bedridden, he is likely to die from pneumonia as a result of having inhaled food or drink because of difficulty swallowing.

Previous: What Happens in the Brain in Alzheimer's Disease

Next: Defining Early Changes

Excerpted from THE ALZHEIMER'S PROJECT: MOMENTUM IN SCIENCE, published by Public Affairs, www.publicaffairsbooks.com.