Measuring Cognitive Impairment & Dementia with Simple Tests

New developments in brain imaging represent major advances in Alzheimer's research and diagnosis. But some low-tech screening tests may offer quick, inexpensive snapshots of a person's cognitive health. Whether they are accurate enough to be used widely for screening is debated, but they may be useful on an individual basis.

Clock Drawing Test

This is one of the best-known dementia screening tests. Patients are asked to draw a clock with the hands pointing to a specified time—for example, 2:45. The most complete, well-organized, accurate, and spatially correct drawing is rated a "10," and the least representative is rated a "1." The more distorted and inaccurate the drawings are, the more likely the person has dementia.

Some research has suggested that the clock drawing test fails to account for important factors like educational level and is of limited value.

Time and Change Test

This measures the ability to tell time and perform a simple math task. The patient is given 60 seconds to read the time on an analog clock with two attempts to get it right. Then, the person is given three quarters, seven dimes, and seven nickels and asked to count out a dollar's worth of change within three minutes, with two attempts allowed.

Sniff Test

Researchers have known for some time that loss of smell is an early warning sign of Alzheimer's. The beta-amyloid plaques that ultimately destroy memory and other cognitive abilities accumulate first in areas of the brain that are responsible for odor perception.

In a paper that was presented at an American College of Neuropsychopharmacology meeting, people with mild cognitive impairment were given a 10-item sniff test. The odors were:

  • lemon
  • strawberry
  • pineapple
  • lilac
  • clove
  • menthol
  • smoke
  • natural gas
  • soap
  • leather

Participants who misidentified more than two odors were five times more likely to progress to Alzheimer's than were those who performed better on the test.

More Quick Tests for Dementia

If dementia is suspected, doctors may administer several tests that examine specific cognitive abilities. To test language, the patient will be asked to name as many items as possible in a category, such as fruits or animals. Naming fewer than 10 items in one minute suggests slowed mental functioning.

Counting backwards by sevens, spelling a word backwards and forwards, and listing the months of the year backwards are tests of working memory and attention. To test reasoning and planning ability, the doctor may ask the patient to describe similarities and differences between two items, such as an apple and an orange.

Listening to a list of words and reciting them back is a common memory test. A person without memory problems should be able to remember at least three words. Often, the person will be given a distracting task to complete before recalling the words. Someone who can't remember at least two words out of three may have cognitive impairment.

Keep in mind that these are screenings but not diagnostic tests and should be given and interpreted by a health care professional. They often don't detect problems in well-educated people and overdiagnose problems in those with little formal education. Poor results indicate probable cognitive impairment, but more sophisticated testing is necessary to make a diagnosis of Alzheimer's disease.

Publication Review By: Peter V. Rabins, M.D., M.P.H.

Published: 21 Mar 2011

Last Modified: 28 Jan 2015