The Changing Brain in Alzheimer's Disease

The Changing Brain in Alzheimer's Disease
No one knows exactly what causes the Alzheimer's disease process to begin or why some of the normal changes associated with aging become so much more extreme and destructive in patients with the disease. We do know a lot, however, about what happens in the brain once AD takes hold and about the physical and mental changes that occur over time. The time from diagnosis to death varies - as little as 3 years if the patient is over 80 when diagnosed, as long as 10 or more years if the patient is younger. Although the course of AD is not the same in every patient, symptoms seem to develop over the same general stages.


PET Scan of Normal Brain		PET Scan of Alzheimer's Disease Brain


	Click here for larger view

Preclinical AD
AD begins in the entorhinal cortex, which is near the hippocampus and has direct connections to it. It then proceeds to the hippocampus, the structure that is essential to the formation of short-term and long-term memories. Affected regions begin to atrophy (shrink). These brain changes probably start 10 to 20 years before any visible signs and symptoms appear. Memory loss, the first visible sign, is the main feature of mild cognitive impairment (MCI) (see the section Criteria for "Probable" Alzheimer's Disease for more on MCI). Many scientists think MCI is often an initial, transitional phase between normal brain aging and AD.


	Click here for larger view

Mild AD
As the disease begins to affect the cerebral cortex, memory loss continues and changes in other cognitive abilities emerge. The clinical diagnosis of AD is usually made during this stage. Signs of mild AD can include:

Memory loss
Confusion about the location of familiar places (getting lost begins to occur)
Taking longer to accomplish normal daily tasks
Trouble handling money and paying bills
Poor judgment leading to bad decisions
Loss of spontaneity and sense of initiative
Mood and personality changes, increased anxiety

The growing number of plaques and tangles first damage areas of brain that control memory, language, and reasoning. It is not until later in the disease that physical abilities decline. This leads to a situation in mild AD in which a person seems to be healthy, but is actually having more and more trouble making sense of the world around him or her. The realization that something is wrong often comes gradually because the early signs can be confused with changes that can happen normally with aging. Accepting these signs and deciding to go for diagnostic tests can be a big hurdle for patients and families to cross.

Moderate AD
By this stage, AD damage has spread further to the areas of the cerebral cortex that control language, reasoning, sensory processing, and conscious thought. Affected regions continue to atrophy and signs and symptoms of the disease become more pronounced and widespread. Behavior problems, such as wandering and agitation, can occur. More intensive supervision and care become necessary, and this can be difficult for many spouses and families. The symptoms of this stage can include:

Increasing memory loss and confusion
Shortened attention span
Problems recognizing friends and family members
Difficulty with language; problems with reading, writing, working with numbers
Difficulty organizing thoughts and thinking logically
Inability to learn new things or to cope with new or unexpected situations
Restlessness, agitation, anxiety, tearfulness, wandering - especially in the late afternoon or at night
Repetitive statements or movement, occasional muscle twitches
Hallucinations, delusions, suspiciousness or paranoia, irritabilityLoss of impulse control (shown through sloppy table manners, undressing at
inappropriate times or places, or vulgar language)
Perceptual-motor problems (such as trouble getting out of a chair or setting the table)

Behavior is the result of complex brain processes, all of which take place in a fraction of a second in the healthy brain. In AD, many of these processes are disturbed, and this is the basis for many distressing or inappropriate behaviors. For example, a person 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. The anger is a mask for his confusion and anxiety. Or, a person with AD may constantly follow her husband or caregiver and fret when the person is out of sight. To a person who cannot remember the past or anticipate the future, the world around her can be strange and frightening. Sticking close to a trusted and familiar caregiver may be the only thing that makes sense and provides security. Taking off clothes may seem reasonable to a person with AD who feels hot and doesn't understand or remember that undressing in public is not acceptable.


	Click here for larger view

Severe AD
In the last stage of AD, plaques and tangles are widespread throughout the brain, and areas of the brain have atrophied further. Patients cannot recognize family and loved ones or communicate in any way. They are completely dependent on others for care. All sense of self seems to vanish. Other symptoms can include:

Weight loss
Seizures, skin infections, difficulty swallowing
Groaning, moaning, or grunting
Increased sleeping
Lack of bladder and bowel control

At the end, patients may be in bed much or all of the time. Most people with AD die from other illnesses, frequently aspiration pneumonia. This type of pneumonia happens when a person is not able to swallow properly and breathes food or liquids into the lungs.


Preclinical AD Click here for larger view		Mild to Moderate AD Click here for larger view		Severe AD Click here for larger view

<< Back | Next >>

Page last updated Aug 29, 2006