AQT-D A Quick Test of Cognitive Speed AQT-D is designed for dementia screening.
A General Introduction to AQT AQT 1 is an objective, reliable and standardized screening test designed to measure cognitive speed through: ability to name familiar visual stimuli automatically (colors and forms). ability to shift rapidly between these stimuli during naming. ability to retrieve information rapidly from short-term memory and engage working memory. The test format is not offensive for the patient. If a patient does not speak English fluently, testing can be performed in the patient s native or dominant language (with an interpreter or translator). Green-red color blindness does not present a problem as the color green is not used as a stimulus. AQT results are not influenced by education, age or gender. AQT can detect early aberration of brain functions involved in rapidly processing familiar visual information. Because brain damage (including early dementia) often lead to cognitive difficulties and mental slowness, performance in the pathological range on AQT is a significant indication of a need for further investigation of the patient. Preparation for Testing Administer the test in a quiet room with adequate illumination. Place the patient in front of you on either side of a table to obtain an optimal test situation. The patient should sit comfortably at the table. If the patient wears glasses, make sure that they are used. Record the total naming time from beginning to end. It is best to use a digital stopwatch to allow for accurate recording of elapsed time.
Trials (untimed) Test Page 1 Trial 1 Color Ask the patient to name only the colors (not the shape). The colors are: blue yellow, black and red (no nuances are allowed). If you feel the patient has not understood the task, repeat the trials. Trial 2 Form Ask the patient to name only the shape of each stimulus (not the color). The forms are: line, square, triangle, circle. The patient is allowed to use his or her chosen word for the forms (e,g., the patient may use "round instead of "circle, but it must be consistent as the test is not a primary memory test). Trial 3 Color & Form Ask the patient to name first the color and then the form, in that order, of each stimulus. Color and form must be named in order with the color named first and the shape last (e.g., red circle, yellow square).
Test (timed) Test Page 2 Color (normal upper limit: 35 sec.) Ask the patient to name the colors as fast and accurate as possible (e.g., blue, yellow ). The patient should be asked to name the color from left to right and top to bottom, as in reading. Start the stopwatch the moment the patient begins to talk. Stop the watch when the patient has named the last color. Note the number of errors the patient made during the test. Record the number of errors on the record form next to the time used. Make sure that both the total time and number errors are recorded. Test Page 3 Form (normal upper limit: 35 sec.) Ask the patient to name the forms as fast and accurate as possible (e.g., line, square, ). The patient must read the shape names line by line from left to right and top to bottom. Start timing when the patient starts naming. Stop timing after the patient has named the last shape. Note the number of errors the patient made during the test. Record the number of errors on the record form next to the time used. Make sure that both the total time and number errors are recorded. Test Page 4 Color & Form (normal upper limit: 70 sec.) Ask the patient to name the color-form combination as fast and accurate as possible (color first and then the form). The patient should name the stimuli line by line from left to right and top to bottom. Start time when the patient begin naming. Stop timing after the patient has named the last stimulus. It is important that the patient name the color first and then the form, in this order. Do not interrupt the patient if the form is named before the color. Note the number of naming errors made during the test. This is most easily recorded by placing a check mark on the record form for each error during testing. Record the total naming time and number of errors on the record form. You do not need to record if the patient consistently uses a different name for one of the forms (e.g., round for circle). Consistent use of a substitute word is not consider a naming error.
What is measured with AQT? AQT measures perceptual (i.e., reaction + response time) and cognitive speed (i.e., perceptual speed + cognitive overhead from demands on attention, working memory and set-shifting). A slowing of naming speed (increase in time used) is considered to reflect an aberration of the brain s ability to quickly identify, process, and name familiar visual stimuli. In this characteristic, AQT differs from other tests which measure ability to deal with cognitive content as, for example, by the MMSE (Mini-Mental State Examination). The temporal-parietal regions of the brain, bilaterally, are especially engaged during the performance of AQT. Patients with brain lesions in these regions (e.g., in Alzheimer s disease) have difficulty engaging these areas of the brain. This results in significantly longer naming times on the AQT. Extended naming times on AQT can also result from other conditions (such as dementias other than Alzheimer s). For these reasons, AQT is not a test intended for differential diagnosis. Extended naming times are indicative that something is wrong and that the patient needs further evaluation. How well can AQT differentiate brain dysfunction from normal performance? Figure 1: shows the distribution of naming times for 116 patients with Alzheimer s and 66 normally aging controls (above age 60 yrs.). Note that all the normally aging controls use less than 70 seconds for color-form naming. Table 1: shows how well AQT (i.e., for color-form combinations) differentiate patients with Alzheimer s from the healthy controls.
Figure 1. 350 Percentiles Plot Split By: DEMENS Row exclusion: REN RAN 0204.svd Color-Form 340 330 320 310 300 290 = Alzheimer (AD) = healthy controls 280 270 260 250 240 Color- Form (sec.) 230 m r220 o210 F -200 r190 o l 180 o170 C 160 150 140 130 120 110 AD NORM Pathological 100 90 80 70 60 50 70 sec 40 30 20 10 Healthy 0 0 20 40 60 80 100 Percentile Distribution (percentages) Table 1: Number correctly classified abnormal: 91 % Number correctly identified healthy: 99.9 % (above 80% = satisfactory. above 90% = excellent)
Questions Question What do I do if the patient ask a question during testing? How do I know testing is reliable? Who should be tested? Should we only test for Alzheimer s Disease? Should AQT be given at any specific time? Answer Say: Continue. If the interruption during testing lasts too long, repeat testing. It is good to perform quality control. If you divide the color-form time by the sum of the color time and form time, the ratio should be less or equal to 1.7. Example: 70 sec (color-form) 35 (color) + 35 (form) = 1.0 You may also re-administer the color-form naming test immediately to determine consistency as there is no evidence of learning or habituation. The test can be giving to any person with suspected cognitive reduction. Criterionreferencing for other populations (e.g., Spanish, Arabic) have been conducted. The cut-off of 70 sec. holds for everyone, who has attained literacy. It is best to give the test when the patient functions best during the day.
Questions Continued. If I want to administer both the MMSE and AQT, which do I give first? What do I do if the patient makes consistent errors, such as naming form before color? What do I do if the patient persists to call the blue form a green form? If the MMSE is 15 points or below, can I then administer AQT? How often can I repeat AQT? What results do I get for mild cognitive impairments (MCI)? Can AQT measure treatment effects? Answers Give AQT first. It does not tire the patient. Do not correct. The main issue is to obtain a time measure. You may re-administer color-form naming with a strong reminder to name the color before the form. Note that naming form before color is appropriate for Spanish. If the patient is consistent it is acceptable. The two test measure different abilities. Try giving AQT to the patient, since even severely involved patients can perform at least the color and the form naming tests. As many times as you need, as there is no learning effect. About one half have slowed naming times between 65 and 70 sec. Redo the test after 6-12 months to catch any disease progression. Yes; cognitive improvement is shown by faster naming times on AQT.
Validation Functional studies of the brain during AQT testing have established that the posterior cortex normally is involved when naming colors, forms, and color-form combinations (illustrated in Figure 3 below). The frontal lobes are normally subordinately involved (normally have less involvement) during testing with AQT. Patients with Alzheimer s disease show relatively early that they have difficulties with activation of the posterior cortex areas particularly the temporal-parietal areas. Instead, these patients show compensatory activation of the frontal lobes during AQT color-form testing. What happens in the brain during color-form naming? Figure 3 Increased Blood Flow Decreased Blood Flow Normal responses Alzheimer s disease When a healthy person names colorform combinations the posterior brain regions (red) are engaged, while the frontal areas (green) are not involved. Patients with Alzheimer s disease show relatively early redu posterior brain regions (green). As a result, color-form nami perform on the AQT color-form test patients instead engage The results reported above are from a study of 66 healthy elderly persons and 116 patients with Alzheimer s disease. 2
The functional brain imaging procedure used in the above study of the cortex is based on 3, 4, 5 the combined activity of the brain s circulatory system and neural activity. By obtaining a measure of regional blood flow during testing a corresponding measure is obtained of the neural activity. During color-form naming studies of normally healthy individuals, increased blood flow can be observed in bilateral posterior temporal-parietal and occipital areas (illustrated at left in Figure 3) while frontal and frontal-temporal areas are not engaged. 6, 7 These observations of normal functions are supported by other studies which show a clear engagement of the posterior areas for recognizing faces. 8 In addition, the lateral areas in the posterior cortex are reported to be active during visual and spatial 9, 10 attention. In particular, the upper and lower parietal areas are engaged when attention must be shifted with changes in spatial localization, as well as when attention must be focused on different dimensions or characteristics of the target. 11 A reduced frontal activity is hypothesized to result from repeated exposures which normally lead to fast stimulus-response learning. 12 Patients with Alzheimer s disease typically exhibit reduced temporal-parietal activity which is directly related to increased AQT color-form naming times. Some conclude that mental slowness in patients with Alzheimer s disease results from generally reduced attention with increased age, 13, 14 while others conclude that mental slowness likely is related to dementias. 15 A mental slowing is observed in normal aging but the slowdown is within standardized AQT limits. 16 AQT is not primarily a memory test, even though performance demands that colors and forms are registered in visual short-term memory. Short-term visual memory capacity has been shown to be limited to from three to four stimuli, and the visual registration occurs in 16, 17 the posterior regions. As AQT uses four different stimuli for the respective colors and forms, we can assume that visual short-term memory is not normally overburdened by the test demands. References 1. Wiig EH, Nielsen NP, Minthon L, Warkentin S. Alzheimer s Quick Test: Assessment of parietal function. San Antonio, TX: Harcourt Assessment, 2002. 2. Warkentin S. Cortical blood flow during AQT testing in cognitively normal and Alzheimer s patients. Malmö: University Hospital MAS Working Paper, 2004. Ingvar DH, Risberg J. Increase of regional cerebral blood flow during mental effort in normals and in patients with focal brain disorders. Experimental Brain Research, 1967; 3:195-211. 4. Raichle ME. Behind the scenes of functional brain imaging: a historical and physiological perspective. Proceedings of the National Academy of Sciences, 1998; 95:765-772.
5. Harrison RV, Harel N, Panescar J, Mount RJ. Blood Capillary Distribution Correlates with Hemodynamic-based Functional Imaging in Cerebral Cortex. Cerebral Cortex, 2002; 12:225-23 6. Wiig EH, Nielsen NP, Minthon L, McPeek D, Said K, Warkentin S. Parietal lobe activation in rapid, automatized naming by adults. Perceptual and Motor Skills, 2002, 94, 1230-1244. 7. Wiig EH, Nielsen NP, Minthon L, Warkentin S. Parietal lobe activation during rapid, automatized naming. Poster presented at 8.th International Conference on Alzheimer s Disease and Related Disorders, Stockholm, July, 2002. 8. Stewart L, Meyer B-U, Frith U, Rothwell JR. Left Posterior BA37 is Involved in Object Recognition: a TMS study. Neuropsychologia, 2001; 39:1-6. 9. Bisley JW, Goldberg ME. Neuronal Activity in the Lateral Intraparietal Area and Spatial Attention. Science, 2003; 299:81-86. 10. Behrmann M, Geng JJ, Shomstein S. Parietal Cortex and Attention. Current Opinion in Neurobiology, 2004; 14:212-217. 11. Yantis S, Schwarzbach J, Serences JT, Carlson RL, Steinmetz MA, Pekar JJ, Courtney SM. Transient neural activity in human parietal cortex during spatial attention shifts. Nat Neurosci 2002, 5:995-1002. 12. Dobbins IG, Schnyer DM, Verfaellie M, Schachter DL. Cortical Activity Reductions during Repetition Priming can Result from Rapid Response Learning. Nature, 2004; 428:316-319. 1 Perry RJ, Hodges JR. Attention and Executive Deficits in Alzheimer s Disease. A Critical Review. Brain, 1999; 122:383-404. 14. Salthouse TA. Aging and Measures of Processing Speed. Biological Psychology, 2000; 54:35-54. 15. Baddeley AD, Baddeley HA, Bucks RS, Wilcock GK. Attentional control in Alzheimer s disease. Brain, 2001; 124:1492-1508. 16. Jacobson JM, Nielsen NP, Minthon L, Warkentin SW, Wiig EH. Multiple Rapid Automatic Naming Measures of Cognition: Normal Performance and Effects of Aging. Perceptual and Motor Skills, 2004, 98, 739-75 17. Todd JJ, Marois R. Capacity Limit of Visual Short-term Memory in Human Posterior Parietal Cortex. Nature, 2004; 428:751-754. 18. Vogel EK och Machizawa MG. Neural activity predicts individual differences in visual working memory capacity. Nature, 2004; 428:748-751.