Alzheimer’s disease: Symptoms, stages, causes, and treatment

Other early signs

In 2016, researchers published findings suggesting that a change in sense of humor might be an early sign of Alzheimer’s.

Recent research suggests that the features of Alzheimer’s, such as brain lesions, may already be present in midlife, even though symptoms of the disease do not appear until years later.

Early-onset Alzheimer’s disease

Early-onset familial Alzheimer’s disease can affect younger people with a family history of the disease, typically between the ages of 30 and 60 years.

It accounts for under 5 percent of all Alzheimer’s cases.


The progression of Alzheimer’s can be broken down into three main stages:

  • preclinical, before symptoms appear
  • mild cognitive impairment, when symptoms are mild
  • dementia

In addition, the Alzheimer’s Association describes seven stages along a continuum of cognitive decline, based on symptom severity.

The scale ranges from a state of no impairment, through mild and moderate decline, eventually reaching “very severe decline.”

A diagnosis does not usually become clear until stage four, described as “mild or early-stage Alzheimer’s.”

Alzheimer’s versus dementia

Dementia is an umbrella term for a range of conditions that involve a loss of cognitive functioning.

Alzheimer’s is the most common type of dementia. It involves plaques and tangles forming in the brain. Symptoms start gradually and are most likely to include a decline in cognitive function and language ability.

Other types of dementia include Huntington’s disease, Parkinson’s disease, and Creutzfeldt-Jakob disease. People can have more than one type of dementia.


There is no single test for Alzheimer’s disease, so doctors will look at the signs and symptoms, take a medical history, and rule out other conditions before making a diagnosis.

They may also check the person’s neurological function, for example, by testing their balance, senses, and reflexes.

Other assessments may include a blood or urine test, a CT or MRI scan of the brain, and screening for depression.

Sometimes the symptoms of dementia are related to an inherited disorder such as Huntington’s disease, so genetic testing may be done.

After ruling out other possible conditions, the doctor will carry out cognitive and memory tests, to assess the person’s ability to think and remember.

Cognitive assessment

To confirm a diagnosis of Alzheimer’s, the following must be present and severe enough to affect daily activities:

  • gradual memory loss
  • progressive cognitive impairment

Questions that may be asked to test cognitive ability include:

woman looking confused

Alzheimer’s can make it hard to remember things.

  • What is your age?
  • What is the time, to the nearest hour?
  • What is the year?
  • What is the name of the hospital or town we are in?
  • Can you recognize two people, for example, the doctor, nurse, or carer?
  • What is your date of birth?
  • In which year did (a well-known historical event) happen?
  • Name the president.
  • Count backward from 20 down to 1
  • Repeat an address at the end of the test that I will give you now (for example, “42 West Street”)

A number of assessment tools are available to assess cognitive function.

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