Cambridge Neuropsychological Test Automated Battery (CANTAB)

Depressive patients performed the Cambridge Neurocognitive Test Automated Battery (CANTAB − http://www.cantab.com), which is a validated and standardized tool for the assessment of neurocognitive functioning [29, 30]. The subset for affective disorders consists of 5 subtests.

A white box is shown in which digits from 2 to 9 appear in a pseudo-random order at a rate of 100 digits per minute. Patients are requested to detect target sequences of digits (e.g., 3-5-7) and respond by pressing a button as quickly as possible.

This test requires retention and manipulation of visuospatial information and provides a measure of strategy as well as working memory errors. Patients are presented a number of boxes on the screen. By selecting boxes and using a process of elimination, patients should find 1 yellow “token” in each of the number of boxes and use them to fill up an empty column on the side of the screen.

Delayed match to sample assesses both simultaneous visual matching ability and short-term visual recognition memory, for nonverbalizable patterns. Patients are presented a complex visual pattern that is both abstract and nonverbal, followed by 4 similar patterns after a brief delay. They have to select the pattern, which exactly matches the sample. In some trials, the sample and the choice patterns are shown simultaneously, and in others, there is a delay before the 4 choices appear.

This is a test of executive function, based upon the Tower of Hanoi test, which assesses both the spatial planning and the working memory subdomains. Patients are shown 2 displays containing 3 colored balls. These displays are presented in such a way that they can be easily perceived as stacks of colored balls held in stockings suspended from a beam. Patients are requested to copy a given pattern by moving only 1 ball at a time.

Emotion recognition task (ERT) measures the ability to identify 6 basic emotions (sadness, happiness, fear, anger, disgust, or surprise) in facial expressions along a continuum of expression magnitude. Computer-morphed images derived from real individuals, each showing a specific emotion, are displayed for 200 ms. The CANTAB is computerized and was carried out twice in every subject, at PRE (baseline) and W5 (5 weeks after treatment).