CERAD – Test battery
The research association “Consortium to Establish a Registry for Alzheimer’s Disease” (CERAD for short) deals with the registration and archiving of Alzheimer’s dementia patients. The organization has put together a standardized battery of tests to simplify the diagnosis of Alzheimer’s disease. The series of tests consists of 8 units dealing with cognitive abilities.
The whole is completed by an intelligence test and the examination of visomotor speed (speed of cooperation between the visual system, the brain and motor skills). Since the CERAD test battery already provides good comparative values with healthy and sick test persons, a relatively objective evaluation of the state of the disease can be made when the test is performed. However, the individual tests are to be evaluated differently and do not all turn out equally differentiated depending on the severity of Alzheimer’s dementia.
The WST tests the verbal intelligence level and thus the crystalline intelligence of the test person. This is independent of age and relatively stable in relation to dementia reduction. Crystalline intelligence comprises factual knowledge and learned behaviours that have developed over the course of a lifetime.
It is strongly related to the so-called fluid intelligence, which describes the basic mental capacities of a person and is innate. In addition to its intelligence-detecting function, it can be used to monitor the course of dementia. The test is carried out with the help of 40 tasks that deal with the correct recognition of terms.
With increasing difficulty, the respondent is presented with word series containing a target word and 4-5 abstract neologisms. The respondent’s task is to grasp the target word as quickly as possible. As the words are technical elements in the further course of the test, the level of the respondent’s education is checked.
The ZVT measures the performance speed of the brain of a test person. This is an intelligence test that is carried out independently of language and refers to the simple ability to count. The speed of performance is based on genetically determined abilities and thus correlates demonstrably with the existing intelligence level of the test person.
The test procedure is relatively simple. Apparently arbitrary numbers are written down on a template. These must be connected in ascending order, with the next highest number always being found in the immediate vicinity of its predecessor.
This task combines the reception of information with its processing and the final conversion into a movement – the visomotor ability is measured. Since the test can be carried out on young people and up to an advanced age, it has a wide diagnostic spectrum and gives the possibility to objectively assess the intelligence of a test person. Verbal fluid: When measuring the verbal fluid, the speed of speech production is checked.
It is possible to control associative thinking by naming different terms with a common characteristic. Which characteristic is concerned can vary from test to test. A common initial letter can be given just as purposefully as a category (e.g. “animals”).
The respondent has to name or write down as many matching terms as possible in 1 to 2 minutes, assuming the given characteristic is present. The memory is also checked. If multiple answers are given, this can be an indication of an impaired short-term memory.
In the Boston Naming Test the visual perception and the resulting word finding and object naming are checked. For this purpose the test person is shown 15 objects or pictures of such objects, which he has to name correctly. The MMST is also part of the CERAD test battery, as it is considered a proven test procedure for controlling cognitive deficits.
The subject is presented with a list of 10 terms, which he or she should read once and memorize. The procedure is repeated three times, with the order of the words varying, but not the selection. Immediate short-term memory is required, especially on the verbal level.
In addition, it is possible to test the learning ability by storing unassociated information. The test person has the task of drawing four geometric figures. These are arranged in ascending order of difficulty and include a circle, a rhombus, two overlapping squares and a cube.
Visoconstructive skills are limited in patients with dementia and the planning of the object to be drawn cannot be fully thought through. Incorrect or imprecise execution is the result. Now the respondent is asked to remember the 10 words of the word list.
This further memory control is aimed at medium-term memorization on a verbal level. By delaying for one minute, the use of short-term memory is circumvented and the episodic memory is checked. The test person is presented with 20 terms, 10 of which correspond to words from the list.
Now the task is to recognize all the words. Due to the facilitated recall conditions, it is possible to differentiate between memory and recall deficits of the memory. Similar to the previous task, the respondent should retrieve information that has already been seen or learned. For this purpose, the respondent is to record the geometric figures shown to him a few tasks before without a template. The non-verbal performance of the memory can be controlled by reproduction without a template.