Verbal Fluency Test and How It Screens for Dementia

Doctor Explaining Verbal Fluency Test Results
LWA/ Getty Images

The verbal fluency test (VFT) is a short screening test that evaluates cognitive function. It’s often used by physicians and other practitioners if there is some concern that the person may have Alzheimer’s or another type of dementia.

By its name, you might guess that the test has something to do with speaking and speed, and you would be correct. The test consists of giving the person 60 seconds to verbally list as many things as possible in a category.

Practitioners often use the verbal fluency test in two different ways:

The person is asked to list all of the animals he can think of in the next 60 seconds. Some variations include asking the test-taker to list all of the fruits, vegetables or the professions he can think of in 60 seconds.

  • Phonetic / Letter Subtest

In the phonetic subtest, a letter is chosen by the test administrator and the person is asked to name all of the words that begin with that particular letter. The most common letters chosen are F, A, and S. Some clinicians will have the individual do a 60 second test on each letter, and others will just choose one letter. One specific type of the phonetic subtest is the Controlled Oral Word Association Test (COWAT).

How Do You Score the Verbal Fluency Test?

To score the VFT, count up the total number of animals or words that the individual is able to produce.

A score of under 17 indicates concern, although some practitioners use 14 as a cutoff. Typically, if someone scores less than 17, the test administrator will use additional tests to further evaluate cognition.

How Accurate is the Verbal Fluency Test in Identifying Dementia in People?

Research has shown that the semantic VFT, in particular, is comparable to both the MMSE and the Clinical Dementia Rating scores, two other tests frequently used in cognitive testing.

The semantic subtest has also been shown to be quite effective in measuring executive functioning and language ability. This may be because the semantic / category subtest seems to require a higher level of thought processes since people have to think of meaning rather than just beginning sounds of words.

The phonetic subtest does not appear as sensitive to the early stages of dementia; however, the test results as people age are quite stable, making it a valuable tool. If someone scores poorly on the phonetic subtest, it is quite likely an indicator of cognitive decline rather than older age.

What Are the Pros and Cons of the Verbal Fluency Test?

Pros:

  • Very brief- The VFT, including both subtests, generally takes anywhere from three to ten minutes to complete from start to end.
  • Quite accurate in screening for dementia- As noted above, the VFT is a quick and relatively easy way to assess someone's cognitive functioning.
  • Little resistance or refusal to participate- Most people agree to take this test and complete it. This may be because listing off words doesn't sound too intimidating to people, and a 60 seconds time limit might also encourage test completion.
  • No cost- Unlike some other cognitive tests where you must purchase test copies and instructions booklets, the VFT has no cost.
  • Easy to administer- The VFT does not require extensive training before administration of the test.
  • Does not require other materials- No materials are needed to conduct this test other than a timing device and a way to track the number of words the person produces.

Cons:

  • Performance can be influenced by level of education and age- Several research studies have documented that the amount of education as well as the person's age (specifically in the semantic subtest) affects performance and should be factored in when using the VFT.
  • The VFT should be used in combination with other screenings for dementia- A diagnosis of dementia should not be solely based on the VFT. Other, more thorough screenings, as well as medical testing and blood work, should be utilized if a person demonstrates difficulty with this test.

Sources:

Assessment 1999 6: 147. Norms for Letter and Category Fluency: Demographic Corrections for Age, Education, and Ethnicity. Accessed August 28, 2012. http://asm.sagepub.com/content/6/2/147

Brazilian Journal of Medical and Biological Research. Category fluency test: effects of age, gender and education on total scores, clustering and switching in Brazilian Portuguese-speaking subjects. Accessed August 28, 2012. 

Clinics (Sao Paulo). 2011 April; 66(4): 623–627. Verbal fluency in Alzheimer's disease, Parkinson's disease, and major depression. Accessed July 17, 2012. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3093793/

Dement Neuropsychol 2009 December;3(4):315-320. Semantic Verbal Fluency test in dementia; Preliminary retrospective analysis. Accessed July 17, 2012.

Dement Neuropsychol 2008 December;2(4):328-332. Phonemic verbal fluency and age A preliminary study. Accessed September 6, 2012. 

Wisconsin’s Alzheimer’s Institute. University of Wisconsin School of Medicine and Public Health. Memory Screening and Early Diagnosis Projects in Wisconsin. Accessed August 26, 2012.

Continue Reading