CogScreen

CogScreen® is a standardized, validated computer-administered and scored neuropsychological test battery developed by Dr. Gary Kay and his colleagues^[51] . The battery was designed to rapidly assess deficits or changes in attention, immediate and working memory, visual perceptual functions, sequencing functions, logical problem solving, calculation skills, reaction time, simultaneous information processing abilities, and executive functions. Initially the test was designed to meet the U.S. Federal Aviation Administration’s (FAA) need for an instrument that could detect subtle changes in cognitive functioning; changes which, left unnoticed, may result in poor pilot judgment or slow reaction time in critical operational situations.

In neuropsychological research CogScreen® has proven to be a highly sensitive test to the presence of mild brain dysfunction secondary to injury or disease and to changes in brain functioning caused by various medications, sleep deprivation, allergen exposure, hypoxia, and normal aging. The outstanding reliability and validity of CogScreen® is well documented in both the comprehensive test manual and in numerous publications [51].

Several versions of CogScreen have been developed for use in specific populations. One version of the battery, CogScreen®-Aeromedical Edition, is used worldwide in the medical re-certification evaluation of pilots with known or suspected neurological and/or psychiatric conditions. For example, the test is used by the FAA to monitor the neurocognitive functioning of HIV seropositive pilots. The battery is also used by major airlines around the world and by military organizations in selecting pilots and in conducting aeromedical research. CogScreen® is a proven predictor of flight performance for both student pilots and commercial aviators.

In addition to the Aeromedical Edition, other versions of CogScreen® have been used to detect the impact of medications on brain function and have provided the basis for regulatory agency approved drug claims such as “non-sedating” (e.g.,52,53,54) and “maintains focus”. Among the pharmaceutical and neutraceutical agents investigated with CogScreen® are the following categories: antihistamines, stimulants (ADHD medications), atypical antipsychotics, antihypertensives, aspartame, cholinesterase inhibitors, statins, antibiotics, antimuscarinics, and hormone replacement therapies.

CogScreen® consists of a series of computerized cognitive tasks, each self-contained and presented with instructions and a practice segment. Completion of practice items at an acceptable level is required prior to administration of each subtest. Responses are made with either a lightpen or touchscreen, thereby eliminating the impact of keyboard experience. CogScreen® can be administered on an individual basis or in a group setting. The test was designed for repeated testing; there are 12 equivalent forms. The full battery is available in Spanish, French and Russian. Individual subtests have been translated into several other languages including; Chinese, Japanese, and Croatian.

Symbol Digit Coding (SDC).
SDC is a computer analogue of the conventional symbol-substitution task found in the Wechsler intelligence tests (Digit Symbol subtest) and the Symbol Digit Modalities Test. Six to nine symbol-digit pairs are displayed continuously throughout the test near the top of the screen. The participant is instructed to remember the symbol-digit pairs for a subsequent memory test. In the center of the screen, a line of symbols in random order is presented with blank spaces directly beneath each symbol. The subject selects the associated digit for each symbol. As each row is completed, a new row appears. Performance measures include response speed (SDCRTC, the median response time for correct responses), response accuracy (SDCACC, the percent of items completed correctly), and thruput (SDCPUT, the number of items correctly completed per minute). The Symbol Digit Coding subtest measures attention, visual scanning, working memory, and speed of information processing.

Symbol Digit Coding Immediate Recall (SDCIR).
This task immediately follows the 120-second trial of the SDC task. Six to nine symbols are presented in random order. The subjects task is to recall the corresponding digits. A measure of recall accuracy (SDCIRACC, percent correct) is the only score for this task. This task provides a measure of short-term visual paired-associate memory.

Symbol Digit Coding Delayed Recall (SDCDR).
This is a 20-minute delayed recall trial of the symbol-digit pairs. A measure of recall accuracy (SDCDRACC, percent correct) is the only score for this task. This task provides a measure of delayed recall from visual paired-associate memory.

Visual Sequence Comparison (VSC).
Two alphanumeric strings are presented simultaneously, one on the right and the other on the left side of the screen. The respondent selects [SAME] or [DIFFERENT] for each pair, indicating whether the same characters are presented in the same order for both sequences. The strings vary in length from four to eight items. For each pair, the strings may differ by one or two items. Half of the 20 sequence pairs present the same sequence, and half present a different sequence. Performance measures include the speed (VSCRTC) and accuracy (VSCRTC) of responses, as well as thruput (VSCPUT; the number of problems correctly completed per minute). Mental functions addressed by this test include visual attention, working memory, verbal-sequential processing, and visual-perceptual speed.

Divided Attention Test (DAT) Part I. -Indicator Alone Task (DATIRTC).
For the Divided Attention Test Indicator Alone task, the respondent watches a cursor move vertically within a circle that is divided into a central, upper, and lower sections. When the cursor crosses into the upper or lower sections, the respondent’s task is to press a box marked “CENTER” with either a lightpen or with a touchscreen stylus. The speed with which the respondent responds (by pressing the CENTER box) when the cursor enters the upper and lower sections is recorded as the median response time for correct responses (DATIRTC). When the respondent presses the CENTER box before the cursor has entered the upper or lower sections of the circle a premature hit is recorded. The total number of premature hits is stored as the DATIPRE score. This subtest measures choice reaction time and impulsivity (inability to control the impulse to respond to the moving target.).

Divided Attention Test Part II
This subtest combines the Visual Sequence Comparison task and the visual monitoring task completed in Divided Attention Test Part I. Both tasks are performed simultaneously. Response speed is measured for both the monitoring task and the visual-sequence comparison task. Accuracy and number of items correctly completed per minute are measured for the sequence comparison task in the dual condition. The Divided Attention Test Indicator Dual Premature Responses represents the number of premature centering responses in the simultaneous task condition. A comparison of performance under single and dual task conditions yields information regarding the respondent’s capacity for multitasking. When the two tasks are presented simultaneously, the test assesses divided attention and working memory.

Other Tests:

51.	Kay, G.G. Cogscreen: Professional Manual . Odessa, Florida. Psychological Assessment Resources, 1995.
52.	Kay, G.G., Eberle, C.A., Kaufman, E., & Hordinsky, J. The effects of antihypertensive medication, hypoxia, and orthostatic stress on cognition. Journal of the International Neuropsychological Society, 2:63, 1996.
53.	Kay, G.G., Berman, B., Mockoviak, S.H., Morris, C.E., Reeves, D., Starbuck, V., Sukenik, E., Harris, A.G. Initial and steady-state effects of diphenhydramine and loratadine on sedation, cognition, mood and psychomotor performance. Archives of Internal Medicine, 157:2350-2356,1997.
54.	Ferris, S., Schneider, L., Farmer, M., Kay, G, & Crook, T. A double-blind, placebo-controlled trial of memantine in age-associated memory impairment. International Journal of Geriatric Psychiatry, 21, 1-8, 2006. Archives of Internal Medicine, 157:2350-2356,1997.