Alzheimer's disease is the most common cause of dementia — the loss of intellectual and social abilities severe enough to interfere with daily functioning. In Alzheimer's disease, healthy brain tissue degenerates, causing a steady decline in memory and mental abilities. Alzheimer's disease is not a part of normal aging, but the risk of the disorder increases with age. About 5 percent of people between the ages of 65 and 74 have Alzheimer's disease, while nearly half the people over the age of 85 have Alzheimer's. Although there's no cure, treatments may improve the quality of life for people with Alzheimer's disease. Those with Alzheimer's — as well as those who care for them — need support and affection from friends and family to cope.

Complications of Alzheimer’s disease

In advanced Alzheimer's disease, people may lose all ability to care for themselves. This can make them more prone to additional health problems such as:

• Pneumonia. Difficulty swallowing food and liquids may cause people with Alzheimer's to inhale (aspirate) some of what they eat and drink into their airways and lungs, which can lead to pneumonia.
• Infections. Urinary incontinence may require the placement of a urinary catheter, which increases the risk of urinary tract infections. Untreated urinary tract infections can lead to more-serious, life-threatening infections.
• Injuries from falls. People with Alzheimer's may become disoriented, increasing their risk of falls. Falls can lead to fractures. In addition, falls are a common cause of serious head injuries, such as bleeding in the brain.

Causes of Alzheimer’s disease

No one factor appears to cause Alzheimer's disease. Instead, scientists believe that it may take a combination of genetic, lifestyle and environmental factors to trigger the onset of symptoms. While the causes of Alzheimer's are poorly understood, its effect on brain tissue is clear. Alzheimer's disease damages and kills brain cells.

Two types of brain cell (neuron) damage are common in people who have Alzheimer's:

• Plaques. Clumps of a normally harmless protein called beta-amyloid may interfere with communication between brain cells. Although the ultimate cause of neuron death in Alzheimer's isn't known, mounting evidence suggests that the abnormal processing of beta-amyloid protein may be the culprit.
• Tangles. The internal support structure for brain cells depends on the normal functioning of a protein called tau. In people with Alzheimer's, threads of tau protein undergo alterations that cause them to become twisted. Many researchers believe this may seriously damage neurons, causing them to die.

Signs & Symptoms of Alzheimer’s disease

Alzheimer's disease 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.

Memory loss

Everyone has occasional lapses in memory. It's normal to forget where you put your car keys or to blank on the names of people whom you rarely see. But the memory problems associated with Alzheimer's disease persist and worsen. People with Alzheimer's may:

• Repeat things
• Often forget conversations or appointments
• Routinely misplace things, often putting them in illogical locations
• Eventually forget the names of family members and everyday objects

Problems 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 disease 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
• Distrust in others
• Increased stubbornness
• Social withdrawal
• Depression
• Anxiety
• Aggressiveness

Diagnosis of Alzheimer’s disease

Doctors can accurately diagnose 90 percent of Alzheimer's cases. Alzheimer's disease can be diagnosed with complete accuracy only after death, when microscopic examination of the brain reveals plaques and tangles. To help distinguish Alzheimer's disease from other causes of memory loss, doctors typically rely on the following types of tests.

Lab tests

Blood tests may be done to help doctors rule out other potential causes of the dementia, such as thyroid disorders or vitamin deficiencies.

Neuropsychological testing

Sometimes doctors undertake a more extensive assessment of thinking and memory skills. This type of testing, which can take several hours to complete, is especially helpful in trying to detect Alzheimer's and other dementias at an early stage.

Brain scans

By looking at images of the brain, doctors may be able to pinpoint any visible abnormalities — such as clots, bleeding or tumors — that may be causing signs and symptoms. Positron emission tomography (PET) can reveal areas of the brain that may be less active and the density of amyloid plaques.

• Magnetic resonance imaging (MRI). An MRI machine uses radio waves and a strong magnetic field to produce detailed images of your brain. You lie on a narrow table that slides into the tube-shaped MRI machine, which makes loud banging noises during scans. The entire procedure can take an hour or more. MRIs are painless, but some people feel claustrophobic in the machine.
• Computerized tomography (CT). For a CT scan, you lie on a narrow table that slides into a small chamber. X-rays pass through your body from various angles, and a computer uses this information to create cross-sectional images, or slices, of your brain. The test is painless and takes about 20 minutes.
• Positron emission tomography (PET). During a PET scan, you'll be injected with a low-level radioactive material, which binds to chemicals that travel to the brain. You lie on a table while an overhead scanner tracks the radioactive material. This helps show which parts of your brain aren't functioning properly. The test is painless and can be particularly useful in distinguishing between different types of dementia.

Treatments of Alzheimer’s disease

Currently, there's no cure for Alzheimer's disease. Doctors sometimes prescribe drugs to improve signs and symptoms that often accompany Alzheimer's, including sleeplessness, wandering, anxiety, agitation and depression. But only two varieties of medications have been proved to slow the cognitive decline associated with Alzheimer's.

Cholinesterase inhibitors

This group of medications — which includes donepezil (Aricept), rivastigmine (Exelon) and galantamine (Razadyne) — works by improving the levels of neurotransmitters in the brain. But cholinesterase inhibitors don't work for everyone. As many as half the people who take these drugs show no improvement. Other people may choose to stop taking the drugs because of the side effects, which include diarrhea, nausea and vomiting.

Memantine (Namenda)

The first drug approved to treat moderate to severe stages of Alzheimer's, memantine protects brain cells from damage caused by the chemical messenger glutamate. It sometimes is used in combination with a cholinesterase inhibitor. Memantine's most common side effect is dizziness, although it also appears to increase agitation and delusional behavior in some people.

Prevention of Alzheimer’s disease

• Right now, there's no proven way to prevent the onset of Alzheimer's disease. Human trials of a promising vaccine against Alzheimer's had to be stopped several years ago because some of the people who received the vaccine developed a serious inflammation of the brain.
• However, you may be able to reduce your risk of Alzheimer's disease by reducing your risk of heart disease. Many of the same factors that increase your risk of heart disease can also increase your risk of dementia. The main players appear to be blood pressure, cholesterol and blood glucose levels.
• Keeping active — physically, mentally and socially — also seems to reduce the risk of Alzheimer's disease.