Serious forgetfulness, mood swings, and other behavioral changes are not a normal part of aging. They may be caused by poor diet, lack of sleep, or too many medicines, for example. Feelings of loneliness, boredom, or depression also can cause forgetfulness. These problems are serious and should be treated. Often they can be reversed.

Sometimes, however, mental changes are caused by diseases that permanently damage brain cells. The term dementia describes a medical condition that is caused by changes in the normal activity of very sensitive brain cells. These changes in the way the brain works can affect memory, speech, and the ability to carry out daily activities.

Alzheimer's disease is the most common cause of dementia in older people (see box below). The second most common cause of dementia in older adults is vascular dementia, which affects the blood vessels in the brain.

What is Alzheimer's disease?

Alzheimer's disease (AD) affects approximately 4 million people in the U.S. Abnormal proteins collect in the brain and appear to cause loss of nerve cells in the areas vital to memory and thinking.

Alzheimer's disease develops slowly. At first, people with AD may have trouble remembering recent events, or the names of familiar people or things. Skills are lost continuously and gradually, though some people decline faster than others. As the disease goes on, symptoms become more easily noticed and serious enough to cause people with AD or their family members to seek medical help.

Multi-infarct dementia is the most common form of vascular dementia, and accounts for 10-20% of all cases of progressive, or gradually worsening, dementia. It usually affects people between the ages of 60-75, and is more likely to occur in men than women.

Multi-infarct dementia is caused by a series of strokes that disrupt blood flow and damage or destroy brain tissue. A stroke occurs when blood cannot get to part of the brain. Strokes can be caused when a blood clot or fatty deposit (called plaque) blocks the vessels that supply blood to the brain. A stroke also can happen when a blood vessel in the brain bursts.

Some of the main causes of strokes are: untreated high blood pressure (hypertension), diabetes, high cholesterol, heart disease.

Of these, the most important risk factor for multi-infarct dementia is high blood pressure.

Because strokes occur suddenly, loss of thinking and remembering skills - the symptoms of dementia - also occurs quickly and often in a step-wise pattern. People with multi-infarct dementia may even appear to improve for short periods of time, then decline again after having more strokes.

Symptoms

Sudden onset of any of the following symptoms may be a sign of multi-infarct dementia: confusion and problems with recent memory, wandering or getting lost in familiar places, moving with rapid, shuffling steps, loss of bladder or bowel control, laughing or crying inappropriately, difficulty following instructions, problems handling money.

Multi-infarct dementia is often the result of a series of small strokes. Some of these small strokes produce no obvious symptoms and are noticed only on brain imaging studies, so they are sometimes called "silent strokes." A person may have several small strokes before noticing serious changes in memory or other signs of multi-infarct dementia.

Transient ischemic attacks, or TIAs, are caused by a temporary blockage of blood flow. Symptoms of TIAs are similar to symptoms of stroke and include mild weakness in an arm or leg, slurred speech, and dizziness. Symptoms generally do not last for more than 20 minutes. A recent history of TIAs greatly increases a person's chance of suffering permanent brain damage from a stroke. Prompt medical attention is required to determine what may be causing the blockage in blood flow and to start proper treatment (such as aspirin or warfarin).

If you believe someone is having a stroke - if a person experiences sudden weakness or numbness on one or both sides of the body, or difficulty speaking, seeing, or walking - call 911 immediately. If the physician believes the symptoms are caused by a blocked blood vessel, treatment with a "clot buster," such as t-PA (tissue plasminogen activator), within 3 hours can reopen the vessel and may reduce the severity of the stroke.

Tags: Alzheimer's Disease, Memory Improvement

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NIA, one of the 27 Institutes and Centers of NIH, leads a broad scientific effort to understand the nature of aging and to extend the healthy, active years of life. In 1974, Congress granted authority to form NIA to provide leadership in aging research, training, health information dissemination, and other programs relevant to aging and older people.