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Symptoms and Signs of Alzheimer's Disease

Doctor's Notes on Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia, a brain disorder that interferes with a person's ability to carry out everyday activities. The brain of a person with Alzheimer's disease has abnormal areas containing clumps (senile plaques) and bundles (neurofibrillary tangles) of abnormal proteins that destroy connections between brain cells, which affects the parts of the brain that control cognitive functions such as thought, memory, and language.

Initial symptoms of Alzheimer's disease include mild, slowly worsening memory loss and memory problems such as: difficulty recognizing familiar people or things, trouble remembering recent events or activities, inability to solve simple math problems, problems finding the right word, and difficulty performing familiar tasks. As the disease progresses, symptoms become more serious and may include an inability to carry out everyday activities, inability to think clearly or solve problems, difficulties understanding or learning new information, problems with communication, increasing disorientation and confusion, and greater risk of falls and accidents due to poor judgment and confusion. In the later stages of Alzheimer's, symptoms can be debilitating and include complete loss of short- and long-term memory, dependence on others for activities of daily living, severe disorientation, behavior or personality changes, loss of mobility, and impairment of other movements such as swallowing.

Medical Author: John P. Cunha, DO, FACOEP
Medically Reviewed on 3/11/2019

Alzheimer's Disease Symptoms

Alzheimer's disease begins with a mild, slowly worsening memory loss. Many older people fear that they have Alzheimer's disease because they can't find their eyeglasses or remember someone's name.

  • These very common problems are most often due to a much less serious condition involving slowing of mental processes with age.
  • Medical professionals call some of these cases benign senescent forgetfulness, age-related memory loss, or minimal cognitive impairment.
  • While these conditions are a nuisance, they do not significantly impair a person's ability to learn new information, solve problems, or carry out everyday activities, as Alzheimer's disease does.

Early warning signs of Alzheimer's disease include memory problems such as the following:

  • Difficulty recognizing familiar people or things (not just forgetting a name)
  • Trouble remembering recent events or activities
  • Inability to solve simple arithmetic problems
  • Problems finding the right word for a familiar thing
  • Difficulty performing familiar tasks

As the disease progresses, however, the symptoms become more serious. They may include the following:

  • Inability to carry out everyday activities, often called activities of daily living, without help - Bathing, dressing, grooming, feeding, using the toilet
  • Inability to think clearly or solve problems
  • Difficulties understanding or learning new information
  • Problems with communication - Speaking, reading, writing
  • Increasing disorientation and confusion even in familiar surroundings
  • Greater risk of falls and accidents due to poor judgment and confusion

In the later stages of the disease, the symptoms are severe and devastating:

  • Complete loss of short- and long-term memory - May be unable to recognize even close relatives and friends
  • Complete dependence on others for activities of daily living
  • Severe disorientation - May walk away from home and get lost
  • Behavior or personality changes - May become anxious, hostile, or aggressive
  • Loss of mobility - May be unable to walk or move from place to place without help
  • Impairment of other movements such as swallowing - Increases risk of malnutrition, choking, and aspiration (inhaling foods and beverages, saliva, or mucus into lungs)

These symptoms typically develop over a period of years. The disease progresses at different rates in different people.

Emotional problems such as depression and anxiety are common in older people. These problems can leave elderly people feeling confused or forgetful. Because these emotional problems are reversible in many people, it is important that they be distinguished from Alzheimer's disease and other brain disorders.

Alzheimer's Disease Causes

We do not know exactly what causes Alzheimer's disease. There is probably not one single cause, but a number of factors that come together in certain people to cause the disease.

  • Most experts believe that Alzheimer's disease is not a normal part of aging.
  • While age is a risk factor for the disease, age alone does not seem to cause it.
  • Family history is another risk factor. The disease does seem to run in some families. However, few cases of Alzheimer's disease are familial. Familial Alzheimer's disease often occurs at a younger age, between ages 30 and 60 years. This is called early-onset familial Alzheimer's disease.

At least three different genes have been linked to Alzheimer's disease.

  • The one we know the most about controls production of a protein called apolipoprotein E (apoE), which helps in distribution of cholesterol through the body.
  • Everyone has one of the 3 forms of the apoE gene. While one form seems to protect from AD, another form seems to increase the risk of developing the disease.
  • The other genes-apart from ApoE-are known to be mutated in some people with the disease. These actually cause the disease in a few rare cases.
  • Probably there are other genes that contribute to Alzheimer's disease, but we haven't found them yet.

Much of the research in Alzheimer's disease has focused on why and how some people develop deposits of the abnormal protein in their brains. Once the process is understood, it may be possible to develop treatments that stop or prevent it.

Dementia, Alzheimer's Disease, and Aging Brains Slideshow

Dementia, Alzheimer's Disease, and Aging Brains Slideshow

In 1906 Auguste Deter, a woman in her early 50s, became the first person diagnosed with Alzheimer's disease, a form of dementia. The disease is named after the doctor who first described it, Alois Alzheimer. The disease is characterized by odd behavior, memory problems, paranoia, disorientation, agitation, and delusions. After Deter’s death, Alzheimer performed a brain autopsy and discovered dramatic shrinkage and abnormal deposits in and around nerve cells.

In 1910 the term “Alzheimer’s Disease” was formally used. In 1974 Congress established the National Institute on Aging (NIA), the primary federal agency supporting Alzheimer’s research.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.