Sunday, April 15, 2012

3 Verbal Learning Tests for Alzheimer’s

Rey Auditory Verbal Learning Test

The Auditory Verbal Learning Test (AVLT) is one of the first commercially available tests for the assessment of memory. It was originally published in 1907 by Édouard Claparède, a renowned Swiss psychologist, and was called the Test de Mémoire des Mots (Test of Memory for Words; Claparède, 1919). It was significantly reworked in the 1960s, and appeared as Rey Auditory Verbal Learning Test (RAVLT). Later it has evolved over the years, and several variations of the test have emerged. The standard RAVLT test uses a list-learning format to examine verbal abilities including immediate memory, efficiency of learning, effects of interference, and recall following short and long delay periods.

Participants are read a list of 15 words aloud by the person administering the test. The entire test takes 10-15 minutes to administer and includes five presentations of a 15 word list (list A), followed by a free recall of a second word list (list B). Finally there is a sixth recall trial of the first list (List A). The test may also assess delayed recall with a seventh recall trial administered after a 20-30 minute delay. Recognition is tested by asking which of 30 words were read aloud from list A and which were not. The words are read at a rate of one word per second. The overall goal of the task is to repeat all of the words the participant can remember in any order.

This verbal learning and memory test (Rey's Auditory Verbal Learning Test-RAVLT) has been found scientifically as an early neuropsychological marker of dementia of Alzheimer's type (DAT).

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The California Verbal Learning Test

The California Verbal Learning Test (CVLT) is a neuropsychological test which can be used to assess an individual's verbal memory abilities.

The tester reads aloud a list, called "Monday's shopping list". The list contains sixteen common words, each of which belongs to one of four categories: thus, there are four fruits, four herbs and spices, etc. The subject is then asked to recall as many of these items as possible.

There are several components to this test. First, the tester records how many items the subject remembers over several repeated trials. Additionally, the tester records whether or not the subject is making use of category information. For instance, suppose the four fruit items are Apples, Bananas, Oranges, Cherries, and suppose the subject can only remember Apples, Bananas and Oranges. If the subject cannot remember the fourth item, but guesses that it is another fruit (e.g., Grapes), the tester concludes that the subject understood the category information in the list. If the subject guesses an unrelated word (e.g., Chicken), the tester concludes that the subject was not able to understand the category information in the list.

Next, the tester may give a second list ("Tuesday's shopping list"), and see if the subject is able to keep the items from each list separate, or if the two lists become confused.

Finally, there is a short delay of 20 minutes, during which the subject is given other tasks to perform, and then the tester again asks the subject to recall Monday's list.

Because it contains so many different components, the CVLT is fairly popular as a neuropsychological test of many aspects of verbal learning and memory. Overall, women tend to perform better than men on the CVLT, especially in their ability to make use of category information. Patients with different kinds of brain damage or disorder also show reliable patterns of performance. For example, patients with Alzheimer's disease tend to be unable to make use of category information (and might recall: Apples, Bananas, Oranges, Chicken) while patients with Parkinson's disease tend to make repetition errors (for example: Apples, Bananas, Oranges, Bananas).

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Buschke-Fuld selective reminding test

Buschke-Fuld selective reminding test is a good measure of recent verbal memory & new learning in elderly subjects, similarly to RAVLT and CVLT, reviewed earlier.  

The test provides 12 words which are selectively rehearsed by the subject until they are memorized. That is, only those words not recalled on the immediately preceding trial are presented. The subject then attends to an interference task or verbal list. Subsequently, after a delay, the subject is asked to recall the words.

When spontaneous recall is impaired, the examiner tests recognition by cueing the subject, or having the subject identify the words from a short list or in a short paragraph.

This strategy allows for the evaluation of various aspects of memory including: learning curve, sensitivity to interference, amount of new learning, recognition & retrieval.

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All three tests are not self-administrated, and they need to be arranged and assessed by the trained professionals.

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