Alzheimer's disease is the most common cause of dementia, which is the loss of intellectual and social abilities severe enough to interfere with daily functioning. Dementia occurs in people with Alzheimer's disease because healthy brain tissue degenerates, causing a steady decline in memory and mental abilities.

Everyone has occasional lapses in memory. It's normal to forget the names of people whom you rarely see. But it's not a normal part of aging to forget the names of familiar people and objects.

Alzheimer's disease - a progressive, degenerative brain disease - causes more than simple forgetfulness. It may start with slight memory loss and confusion, but it eventually leads to irreversible mental impairment that destroys a person's ability to remember, reason, learn and imagine.

Although there's no cure for Alzheimer's disease, researchers have made progress. Treatments are available that improve the quality of life for some people with Alzheimer's. Also, more drugs are being studied, and scientists have discovered several genes associated with Alzheimer's, which may lead to new treatments to block progression of this complex disease.

In the meantime, caring for someone with Alzheimer's takes patience and a focus on the things a person can still do and enjoy. Those with Alzheimer's - as well as those who care for them - need support and affection from friends and family to cope.

The causes of Alzheimer's are poorly understood, but its effect on brain tissue has been demonstrated clearly. Alzheimer's damages and kills brain cells.

A healthy brain has billions of nerve cells called neurons. Neurons generate electrical and chemical signals that are relayed from neuron to neuron to help you think, remember and feel. Chemicals called neurotransmitters help these signals flow seamlessly between neurons.

Initially in people with Alzheimer's, neurons in certain locations of the brain begin to die. When they die, lower levels of neurotransmitters are produced, creating signaling problems in the brain.

Most people with Alzheimer's share certain signs and symptoms of the disease. These may include:

Increasing and persistent forgetfulness: At its onset, Alzheimer's disease is marked by periods of forgetfulness, especially of recent events or simple directions. But the mild forgetfulness often persists and worsens. People with Alzheimer's may repeat things and forget conversations or appointments. They routinely misplace things, often putting them in illogical locations. They frequently forget names, and eventually, they may forget the names of family members and everyday objects.

Difficulties with abstract thinking: People with Alzheimer's may initially have trouble balancing their checkbook, a problem that progresses to trouble recognizing and dealing with numbers.

Difficulty finding the right word: It may be a challenge for those with Alzheimer's to find the right words to express thoughts or even follow conversations. Eventually, reading and writing also are affected.

Disorientation: People with Alzheimer's often lose their sense of time and dates, and may find themselves lost in familiar surroundings.

Loss of judgment: Solving everyday problems, such as knowing what to do if food on the stove is burning, becomes increasingly difficult, eventually impossible. Alzheimer's is characterized by greater difficulty in doing things that require planning, decision making and judgment.

Difficulty performing familiar tasks: Once-routine tasks that require sequential steps, such as cooking, become a struggle as the disease progresses. Eventually, people with advanced Alzheimer's may forget how to do even the most basic things.

Personality changes: People with Alzheimer's may exhibit mood swings. They may express distrust in others, show increased stubbornness and withdraw socially. Early on, this may be a response to the frustration they feel as they notice uncontrollable changes in their memory. Depression can often coexist with Alzheimer's disease. Restlessness also is a common sign. As the disease progresses, people with Alzheimer's may become anxious or aggressive and behave inappropriately.

Currently there is no proven way to prevent the onset of Alzheimer's disease, some factors that may help to prevent the onset are -

Healthy aging: Some of the most recent research indicates that taking steps to improve your cardiovascular health, such as losing weight, exercising and controlling high blood pressure and cholesterol, may also help prevent Alzheimer's disease.

Mental fitness: Maintaining mental fitness may delay onset of dementia. Some researchers believe that lifelong mental exercise and learning may promote the growth of additional synapses, the connections between neurons, and delay the onset of dementia. Other researchers argue that advanced education gives a person more experience with the types of memory and thinking tests used to measure dementia.

People with Alzheimer's disease often experience a mixture of emotions - confusion, frustration, anger, fear, uncertainty, grief and depression. Since a person with Alzheimer's tends to be upset, the ability to think clearly declines even more.

Providing care for a person in family with Alzheimer's disease is physically and emotionally demanding. Feelings of anger and guilt, frustration and discouragement, worry and grief, and social isolation are common.

Some tips that may help families cope with the condition are:

• Asking friends or other family members for help when you need it
• Taking care of your health
• Learning as much about the disease as you can
• Asking questions of doctors, social workers and others involved in the care of your loved one
• Joining a support group

Many people with Alzheimer's and their families benefit from counseling or local support groups.