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What Is Alzheimer’s Disease?

Alzheimer's disease is a progressive neurodegenerative condition. It is one of the most common forms of dementia, a group of symptoms that lead to a decline in mental function severe enough to disrupt daily life. Alzheimer's disease causes problems with a person's memory and ability to learn, reason, make judgments, communicate and carry out daily activities.

First identified in 1907 by the German physician Alois Alzheimer, the illness afflicts about 5 million Americans. An estimated one in nine adults aged 65 and older lives with the disease.

Symptoms and Diagnosis

People with Alzheimer's disease first develop subtle memory loss and personality changes that differ from normal age-related memory problems. They seem to tire or become upset or anxious more easily. They do not cope well with change. For example, they can follow familiar routes, but traveling to a new place confuses them and they can easily become lost. In the early stages of the illness, people with Alzheimer's disease are particularly susceptible to depression.

As the disease progresses, memory loss worsens and decision making becomes more difficult. A person with Alzheimer's can become angry when family members try to help. Eventually, social life becomes more difficult, people may not recognize long-time friends or family members, and may become more isolated. In late stages of Alzheimer's people begin to lose physical coordination and may need help with daily functions and taking care of themselves. A person may notice changes in themselves, or changes may first be observed by family members or friends.

Diagnosis of Alzheimer's typically involves physical and neurological exams, a thorough medical history and mental status evaluation. It may involve brain imaging (such as MRI or CT) which could identify other causes of problems such as stroke, tumor or head trauma. A psychiatrist or other physician may order tests to rule out other possible medical conditions that can mimic Alzheimer's symptoms, such as:

  • Depression
  • Thyroid conditions
  • Vitamin deficiencies caused by poor nutrition or illnesses
  • Urinary track or other infections
  • Reactions to medications or drug interactions

Physicians must carefully review a person's symptoms and take a thorough medical history to correctly diagnose Alzheimer's disease.

Alzheimer's Disease Symptoms

  • Problems with short-term and long-term memory
  • Problems with decision-making, problem solving and judgment
  • Difficulty producing or understanding language
  • Loss of spatial abilities (difficulty judging shapes and sizes and the relationship of objects in space)
  • Personality and behavior changes (depression, apathy, withdrawal from usual activities)
  • Apathy (passive behavior, sleeping more than usual or not wanting to do usual activities)
  • Loss of ability to learn new information
  • Confusion with time and place (getting lost in familiar places)

The presence of any or all of these symptoms is not a sure indicator of Alzheimer's disease; a complete examination by a physician is required.

While the vast majority of people with Alzheimer’s are in their mid-70s or older, an estimated 5 percent of people with Alzheimer’s have early-onset Alzheimer’s, affecting people before age 65. The greatest risk factor for Alzheimer’s is age. Family history is also a risk factor. Heredity (genes) and/or environmental factors may contribute.


While Alzheimer's disease is irreversible, there are medications and supportive treatments that can help with memory and behavior concerns. Patients and their loved ones can do much to cope with the illness and its effects.

The U.S. Food and Drug Administration (FDA) has approved four medicines for Alzheimer's disease. They may help delay or slow symptoms of the disease. Several medications called cholinesterase inhibitors (Razadyne® (galantamine), Exelon® (rivastigmine) and Aricept® (donepezil)) are prescribed for mild to moderate Alzheimer's disease. The medication Namenda® (memantine) is prescribed to treat moderate to severe Alzheimer's disease. It can help delay some symptoms of moderate to severe Alzheimer's and allow individuals to maintain some functions a little longer than they would without the medication. A fifth medication is called Namzaric; it is a combination of donepezil and memantine.

Patients and families may also benefit from support groups and counseling. Family members can learn ways to help their relative manage the illness and they can learn coping skills to lessen the stress of caring for a relative with Alzheimer's disease.

(See more on Alzheimer's medications (.pdf) from the Alzheimer's Association and Patient and Caregiver Guide: Antipsychotic Medications to Treat Agitation or Psychosis in Adults with Dementia (.pdf) from APA.)

Tips for Coping with Memory and Behavior Challenges

The Alzheimer's Association offers some tips for caregivers on coping with memory and behavior issues. These strategies are intended to help address needs that the person with Alzheimer's may have, promote physical and emotional comfort, and help manage behavior symptoms.

  • Monitor personal comfort. Check for pain, hunger, thirst, constipation, full bladder, fatigue, infections and skin irritation. Maintain a comfortable room temperature.
  • Avoid being confrontational or arguing about facts. For example, if a person expresses a wish to go visit a parent who died years ago, don't point out that the parent is dead. Instead, say, "Your mother is a wonderful person. I would like to see her too."
  • Redirect the person's attention. Try to remain flexible, patient and supportive by responding to the emotion, not the behavior.
  • Create a calm environment. Avoid noise, glare, insecure space and too much background distraction, including television.
  • Allow adequate rest between stimulating events.
  • Acknowledge requests and respond to them.
  • Look for reasons behind each behavior. Consult a physician to identify any causes related to medications or illness.

These strategies are intended to help address needs that the person with Alzheimer's may have, promote physical and emotional comfort, and help manage behavior symptoms.

The Alzheimer's Association also reminds caregivers not to take the behavior personally and to recognize that the person is not just "acting mean or ornery," but is having symptoms of the disease. Caregiving can be stressful and difficult, as well as emotionally and physically exhausting. Caregivers need to take time to care for themselves, too. Taking time to relax, exercise and talk with friends is important. Sharing experiences with others can help.

Related Conditions

Not all dementia is caused by Alzheimer's. Alzheimer's is one of a group of conditions called neurocognitive disorders. Problems with memory, thinking and reasoning can also be caused by stroke, Parkinson's Disease, HIV Infection, Huntington's Disease, and traumatic brain injury. Delirium is a temporary state of confusion, disorientation or problems with attention that develops over a short period of time. It is caused by an underlying medical condition, medication or other substance, or exposure to a toxin.

Physician Review

Ranna Parekh, M.D., M.P.H.

Lior Givon, M.D., PH.D., Assistant Professor of Psychiatry, Cambridge Health Alliance

January 2019

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