Alzheimer's Disease

Overview

Alzheimer’s disease is the most common type of dementia, a brain disease in which a person’s memory and thinking (cognitive) abilities progressively worsen over time. In addition to significant memory loss, patients with Alzheimer’s disease experience impaired communication, inability to concentrate, loss of judgment, and visual problems. Alzheimer’s disease is incurable, and individuals with the condition eventually become completely unable to communicate or perform any normal activities of life.

Women have a greater risk for developing Alzheimer’s disease than men. The condition usually affects older adults after age 60; however, there is a much less common form of the condition, termed early-onset Alzheimer’s disease that occurs between ages 30 to 60.

Causes and Risk Factors

Different types of dementia damage the brain in different ways. In patients with Alzheimer’s disease, the brain develops high levels of abnormal proteins (beta-amyloid plaques) and tangles of fibrous material (tau tangles). As the beta-amyloid plaques and tangles increase, the nerve cells (neurons) in the brain become damaged and stop working properly. Consequently, the brain shrinks in size and loses function. Research suggests that the disease slowly starts damaging the brain many years before symptoms develop.

The initial trigger for Alzheimer's disease is unknown, but Alzheimer’s has been linked to the same factors that cause heart disease, such as diabetes, high blood pressure, high cholesterol level, and smoking. Other factors include advanced age, a family history of Alzheimer’s disease, low levels of dietary vegetables and fruit, low levels of physical activity, limited social activities, low levels of mental stimulation, and a history of head injury.

Alzheimer's Symptoms

The main symptoms of Alzheimer’s disease include memory loss, loss of language skills, inability to concentrate, and impaired judgment. The disease actually starts several years before any symptoms are experienced, and the initial symptoms are very mild because the disease progresses so slowly. Alzheimer’s disease starts by striking the hippocampus (the key area of the brain for learning and memory); therefore, one of the earliest symptoms is memory loss - particularly the inability to remember newly learned information. Eventually, the disease affects other parts of the brain, resulting in language problems, visual problems, behavioral abnormalities, loss of function, and profound debilitation.

hippocampus within the brain

Common Symptoms of Alzheimer’s Disease:

  • Memory loss, especially recently learned information, such as difficulty remembering dates and recent events or needing repeated reminders
  • Difficulty speaking, problems finding words, and inability to carry on a conversation
  • Difficulty with counting or simple calculations
  • Problems with completing familiar tasks, such as forgetting how to drive home
  • Misplacing objects and accusing others of stealing
  • Vision problems
  • Impaired judgment
  • Confusion and disorientation with changes in environment, such as not knowing where they are or how they got there
  • Difficulty performing daily activities
  • Personality changes
  • Agitation, anxiety, and depression
  • Hallucinations
  • Delusions
  • Withdrawal from social activities
  • Sleep difficulties
  • Inability to speak, swallow, eat, or walk.

Diagnosis and Treatment

When Alzheimer's disease is suspected, laboratory tests are performed to rule out other causes of dementia, such as a vascular dementia, which is caused by strokes. Computed tomography (CT) and magnetic resonance imaging (MRI) provide detailed images of the brain and are performed to check for other brain disorders, such as a brain tumors or strokes. In order to diagnose Alzheimer's disease, patients undergo several tests of memory, attention, language, and math skills. Patients are also evaluated for personality changes and their ability to perform activities of daily living.

Alzheimer’s disease is an irreversible condition. There is no cure or treatment to stop the progression of this disease; however, there are some treatments to temporarily alleviate some of the symptoms.

Medications for Memory and Cognitive Function:

  • Cholinesterase inhibitors help memory loss and thinking problems by increasing the level of acetylcholine, a naturally occurring chemical that aids communication between nerve cells.
  • Memantine improves memory and other cognitive abilities by regulating a chemical in the body called glutamate.
  • High dose vitamin E is an antioxidant that may protect brain cells from injury.

Medications for Behavioral Symptoms:

  • Antidepressants to treat depressed moods
  • Anxiolytics to treat anxiety
  • Antipsychotic medications for hallucinations and agitation.

Other:

  • Comfort measures to manage pain, hunger, thirst, etc.
  • Calm, reassuring environment
  • Adequate rest.

Prevention

Currently, there is no known way to prevent Alzheimer's disease; however, there are numerous ongoing research studies in search of ways to prevent the onset of the disease or halt its progression.

Previous studies have suggested that Alzheimer’s disease is associated with many of the risk factors for heart disease. All individuals are advised to avoid smoking, control high blood pressure and diabetes, and consume a healthy diet high in vegetables and fruit, because these measures may be beneficial in lowering the risk for both diseases.

Other studies have shown that higher levels of education, mentally challenging activities, stimulating jobs, and engagement in frequent social activities may also reduce a person’s risk of developing Alzheimer’s.

Sources

  • Seeley WW, Miller BL. Chapter 371. Dementia. In: Longo DL, Fauci AS, Kasper DL, Hauser SL, Jameson J, Loscalzo J. eds. Harrison's Principles of Internal Medicine, 18e. New York, NY: McGraw-Hill; 2012.
  • Alzheimer’s Disease Fact Sheet. National Institute of Heath, National Institute on Aging website. http://www.nia.nih.gov/alzheimers/publication/alzheimers-disease-fact-sheet. Accessed July 6, 2014.
  • Alzheimer’s Association website. http://www.alz.org/alzheimers_disease_what_is_alzheimers.asp. Accessed July 6, 2014.
  • Alzheimer’s Disease. Mayo Clinic website. http://www.mayoclinic.org/diseases-conditions/alzheimers-disease/basics/definition/con-20023871. Accessed July 6, 2014.