Alzheimer’s disease, a form of dementia, is a progressive disease that causes a loss of brain function, such as memory.  In Alzheimer's disease, brain cells degenerate and die, causing a steady decline in memory and mental function. 

Alzheimer's disease is caused by a combination of genetic, lifestyle and environmental factors that affect the brain over time. Alzheimer’s is believed to be the cause of multiple factors coming together such as age, family history, gender, head injuries, and vascular disease. 

Alzheimer's disease causes the gradual death of brain cells, reducing the number of healthy brain cells and the connections among them. These effects typically lead to brain shrinkage. (4)

People with Alzheimer’s disease may have difficulty with many mental functions, such as memory, thinking and reasoning, making judgments and decisions, planning and performing familiar tasks, in addition to changes in personality and behavior.

There's no specific test today that confirms Alzheimer's disease. It is distinguished from other causes of memory loss by performing physical and neurological exams, mental status and neuropsychological testing, brain imaging such as magnetic resonance imaging, testing cerebrospinal fluid and other lab tests to exclude other possible causes of the symptoms apparent on the patient. 

Alzheimer's disease is mainly treated by drugs (cholinesterase inhibitors, and memantine). Other measures can be taken to reduce the effects of the disease on the patient, such as creating a safe and supportive environment, and using alternative medicine such as curcumin and ginkgo. 

There are many ways that may delay the onset of Alzheimer's disease such as regular exercise, social engagement, and a healthy diet. 

The rate of the progress of Alzheimer’s disease and to what extent it affects the patient is variable.

The World Health Organization reports that Alzheimer's disease is the most common cause of dementia. It contributes 60 to 70% of 47.5 million cases of dementia in the world.

Alzheimer’s disease is a progressive disease that affects memory, thinking and behavior. The symptoms develop and become more severe with time due to the gradual death of cells in different parts of the brain. The disease is the most common type of dementia and affects mainly the elderly. 

The exact cause of Alzheimer's disease in still unknown. Alzheimer's disease is thought to be the result of a combination of genetic, lifestyle and environmental factors that affect the brain over time. In rare cases, Alzheimer's is caused by specific genetic changes that guarantee a person will develop the disease. 

Alzheimer’s is believed to be the cause of multiple factors coming together. These factors include:

• Age

Age is the greatest factor in the development of Alzheimer’s disease as the disease is most common in the elderly.

• Family history

People with a family member diagnosed with Alzheimer’s disease are at an increased risk of developing the disease themselves. 

• Head injuries

People who had a severe head injury seem to have a greater risk of Alzheimer's disease. 

• Heart and vascular diseases

Heart and vascular diseases seem to be strongly linked to developing Alzheimer’s disease. Additionally, multiple risk factors, such as obesity, smoking, high blood pressure and high blood cholesterol, are common between heart and vascular diseases and Alzheimer’s disease. 

• Down syndrome

People with Down syndrome are at a higher risk for developing Alzheimer’s disease. 

• Gender

Women seem to be more likely than men to develop Alzheimer's disease. 

• Mild Cognitive Impairment (MCI)

Mild Cognitive Impairment (MCI) is a stage between normal forgetfulness due to aging, and the development of Alzheimer's disease. Thinking and memory problems in people with MCI do not interfere with daily life as they tend to be mild. Not everyone with MCI develops Alzheimer's disease.

Alzheimer's disease damages and kills brain cells. A brain affected has many fewer cells and many fewer connections among surviving cells than does a healthy brain. Alzheimer's disease causes a significant shrinkage in the brain as more and more brain cells die.

There are two major brain abnormalities associated with Alzheimer’s disease that are thought to be responsible for the death of brain cells. These abnormalities are: 

• Plaques. These are clusters of a protein known as beta-amyloid that accumulate between nerve cells. These clusters may damage and destroy brain cells in several ways, including interfering with cell-to-cell communication. 
• Tangles. Brain cells depend on tau protein as it allows the internal support and transport system to carry nutrients and other essential materials throughout the long extensions of brain cells. Threads of this protein may twist into abnormal tangles inside brain cells, causing a failure in the transport system. This failure has been linked to the decline and death of brain cells.

Other abnormalities thought to play a role in Alzheimer’s disease is the disruption in the activity of neurotransmitters that carry signals between brain cells. 

The signs and symptoms of Alzheimer’s disease appear mild at first and worsen overtime. Alzheimer’s disease affects many areas of mental function, including:

• Memory: Memory loss associated with Alzheimer’s persists and worsens overtime. Memory problems include repeating statements and questions, forgetting conversations, routinely misplacing possessions, getting lost in familiar places, forgetting the names of family members, and trouble finding the right words to identify objects. 
• Thinking and reasoning: This especially manifests in the inability to recognize and deal with numbers. 
• Making judgments and decisions: This creates difficulties with responding effectively to everyday problems. 
• Planning and performing familiar tasks: Forgetting how to perform basic tasks, such as dressing. 
• Changes in personality and behavior: Alzheimer’s disease can affect the patient’s behavior and feelings, potentially leading to depression, apathy, social withdrawal, mood swings, distrust in others, irritability and aggressiveness, in addition to changes in sleeping habits. 

There is no specific test that confirms Alzheimer's disease, but multiple tests can be performed to help detect the disease. These tests include:

• Physical and neurological exams

Physical and neurological exams check overall neurological health by testing reflexes, muscle tone and strength, sense of sight and hearing, coordination, and balance. 

• Lab tests

Lab tests that help detect other causes of memory loss and confusion, such as thyroid disorders and vitamin deficiencies, are performed to rule them out. 

• Mental status and neuropsychological testing

Mental status and neuropsychological testing help assess memory and other thinking skills. Longer forms of neuropsychological testing may provide additional details about mental function and compare the results with others of a similar age and education level. 

• Cerebrospinal fluid test

Cerebrospinal fluid tests are used to spot dementia that is progressing rapidly or very young onset dementia. Spinal fluid can be tested for biomarkers that may point out to Alzheimer's disease. 

• Brain imaging

Brain imaging is used to spot visible abnormalities related to conditions other than Alzheimer's disease such as strokes, trauma or tumors, that may cause cognitive changes. Brain imaging technologies include:

• Magnetic Resonance Imaging (MRI)

The Magnetic Resonance Imaging (MRI) uses radio waves and a magnetic field to produce detailed images of the brain which may help assess whether the brain has undergone any shrinkage. 

• Computerized Tomography (CT)

CT scans produces cross-sectional images of brain. It is mainly used to rule out tumors, strokes and head injuries. 

• Positron Emission Tomography (PET)

PET is a test used to show overall activity in various regions of the brain. New PET techniques can detect levels of plaques and tangles in the brain, but these new techniques are mainly used in research.

• Genetic testing

Genetic testing isn't recommended for a routine Alzheimer's disease evaluation, with an exception for people who have a family history of early-onset Alzheimer's disease. 

Currently, there is no cure for Alzheimer's disease, but several treatments may help in lessening cognitive and behavioral symptoms. These treatments include:

• Drugs

There are two types of drugs that are currently used to treat the cognitive symptoms of Alzheimer’s disease:

- Cholinesterase inhibitors

Cholinesterase inhibitors provide a neurotransmitter called acetylcholine which is depleted in the brain of Alzheimer's patients. Increasing the levels of this neurotransmitter helps boost cell-to-cell communication. 

- Memantine

Memantine is used to slow the progression of symptoms in patients with moderate to severe Alzheimer's disease. 

• Creating a safe and supportive environment

Events or changes in a person's surroundings play a role in triggering behavioral symptoms, so creating a safe and supportive environment is important to help lessen effects on cognition and behavior. This can be done by adapting the living situation to the needs of a person with Alzheimer's such as establishing and strengthening routine habits, and minimizing memory-demanding tasks. 

• Exercise

Regular exercise helps to improve mood and maintain the health of joints, muscles and the heart. Exercise can also promote restful sleep. 

• Nutrition

People with Alzheimer's may forget to eat and drink enough, leading to dehydration and constipation, so their eating habits should be monitored. 

• Alternative medicine

Herbal mixtures, vitamins and other supplements may support cognitive health or prevent or delay Alzheimer's. However, there's no strong evidence that supports their effects in slowing the progression of cognitive decline. 

Some of the treatments that have been studied recently, include:

Omega-3 fatty acids

Omega-3 fatty acids found abundantly in fish may help prevent cognitive decline; however, Studies done on fish oil supplements haven't shown any benefit. 

Curcumin

This herb contains anti-inflammatory and antioxidant properties and may have an effect on chemical processes in the brain. The curcumin herb comes from turmeric. 

Ginkgo

A study funded by the NIH on the effects of gingko in preventing or delaying Alzheimer’s disease found that the plant has no effect. 

Vitamin E

Taking vitamin E supplements for the prevention of Alzheimer’s disease is not effective, but it may help patients with the disease delay its progression. Patients should always consult their doctor before taking any new medication or supplements.

Brain changes caused by Alzheimer’s begin to affect physical function in the final stages of Alzheimer’s disease. Issues arising from these effects may include problem swallowing, balance, and problems with bowel and bladder control. These effects can also increase the probability of other health problems, such as:

• Inhaling food or liquid into the lungs (aspiration)
• Pneumonia and other infections
• Falls
• Fractures
• Bedsores
• Malnutrition or dehydration 

The direct cause of Alzheimer's disease is still unknown so there are no known methods that have clear effects on preventing the disease. There are, however, some steps that may help delay the onset of Alzheimer's disease:

Regular exercise

Regular exercise helps the brain make new connections and maintain old ones, so it may be effective in protecting against Alzheimer’s disease. 

Social engagement

Being socially engaged may help protect against Alzheimer’s disease in later life. this may be done by creating and maintaining a network of friends.

Healthy diet

Following healthy eating habits may reduce the risk of Alzheimer’s disease. 

Mental stimulation

Staying mentally active may reduce the risk of Alzheimer's disease. Activities that help with this include reading, writing, learning foreign languages, playing musical instruments and taking part in adult education courses. 

Stress management

Simple stress management techniques can minimize stress which may have a substantial effect on the brain leading to shrinkage in key memory areas, obstructing nerve cell growth, and increasing the risk of Alzheimer’s disease. Stress management tools include breathing exercises and relaxation activities, such as daily walks. 

Quitting smoking

Smoking is a preventable risk factor for many diseases including Alzheimer’s. Stopping smoking may have immediate benefits on the brain benefits from improved circulation. 

Controlling blood pressure and cholesterol levels

High blood pressure and high total cholesterol are associated with an increased risk of Alzheimer’s disease, so controlling blood pressure and cholesterol levels may help reduce the risk of Alzheimer’s disease. 

Healthy weight

Obesity is a risk factor for developing Alzheimer’s disease, so losing weight can reduce its effects on the brain. 

Drinking in moderation

Heavy alcohol consumption can greatly increase the risk of Alzheimer’s disease.

Alzheimer's disease is incurable and the damage it does is irreversible. According to an American study conducted by the Johns Hopkins Bloomberg School of Public Health, the average amount of time a person with Alzheimer's will live is eight years after symptoms start to develop. 

The effects of Alzheimer’s disease vary considerably from person to person and depend on age as well as the type and severity of other medical conditions. People with Alzheimer's disease often die of a medical complication such as pneumonia or the flu. Persons with Alzheimer's will die when all body systems fail because of the disease. 

Numbers released by the World Health Organization (WHO) show that Alzheimer's disease is the most common cause of dementia contributing to 60–70% of cases in the world. Worldwide, the WHO reports that there are 47.5 million people that suffer from dementia of various causes , including Alzheimer's disease, with 9.9 million new cases diagnosed every year.