Executive Function

Specific conditions in the Verbal Fluency test and Sorting Test from the D-KEFS and the Trail-making test Part B (Trails B) were used to assess different aspects of executive function (Delis et al., 2001; Wechsler, 1997a).

Verbal Fluency subtest (Standard and Alternate Form)

Verbal fluency and mental flexibility were measured using both the standard and alternate versions of the Verbal Fluency subtest from the D-KEFS (Delis et al., 2001) (See Appendix D). The test derives measures for phonemic fluency, semantic fluency, and semantic switching (i.e., the individual’s ability to generate words starting with a given letter and a given category, and their ability to switch between two semantic categories respectively). The phonemic or letter fluency score was the focus of assessment in the present study as this measure has proven to be more sensitive to neuropsychological insult (Lezak et al., 2004). Furthermore, there is controversy about whether the switching condition is a true measure of executive function (Baldo, Shimamura, Delis, Kramer & Kaplan, 2001).

Standard administration procedures were followed, as described in Delis et al. (2001). In the letter fluency task, the participant is given 60 seconds to say as many words as possible beginning with a specific letter. The examinee completes three trials with different letters. The commonly used letters F-A-S were employed in this assessment task (See Appendix E).

Sorting Test (Standard and Alternate Form)

Concept formation and problem-solving behaviour was assessed through the use of both the standard and alternate forms of the D-KEFS Sorting test (Delis et al., 2001) (See Appendix F and G). As per the previous subtest, this measure was administered according to the standard administration guidelines set out by Delis et al. (2001).

Whilst the D-KEFS Sorting Test consists of three measures; ‘free sorting’, ‘confirmed sorts’, and ‘sort recognition’, the free sort condition was the focus of assessment as it is more demanding than the recognition format (Johnson, 1990). The free sorting task requires the participant to group a series of cards on the basis of their perceptual features or the verbal/semantic information written on the cards. The participant is then required to describe the concepts employed to generate each sort. A maximum of four minutes is given in order to identify the eight different sort options. In this condition the participant receives a score for the number of sorts accurately identified (confirmed sorts).

Trail-Making Test – Part B

Part B of the Trail-making test was utilised to measure a component of executive function – mental flexibility (Strauss et al., 2006) (See Appendix A). This measure was administered according to the guidelines set out in the Compendium of Neuropsychological Tests – Third Edition (Strauss et al., 2006, page 656). In this task the participant draws a line to connect twenty-five consecutive numbers and letters randomly placed on a single page. The examinee starts with the lowest numbers and then alternates between consecutive numbers and letters, as quickly as possible without making any mistakes or lifting the pencil from the page.

This test shares some similarities with Part A of the Trail-making subtest; also requiring adequate motor speed, agility, and visual scanning for its successful completion (Schear & Sato, 1989; Shum et al., 1990). However the attentional switching component of the task places additional demands on cognitive flexibility, and probes one’s ability to deal with multiple stimuli or thoughts at once (Arbuthnott & Frank, 2000; Kortte et al., 2002; Eson et al., 1978).

2.2.2 Measures of Mood and Affect

Mood was assessed using two self-reported measures of mood symptoms. The Beck Depression Inventory – Second Edition (BDI-II) (Beck et al., 1996) and the State Trait Anxiety Inventory - Form Y (STAI) (Spielberger et al., 1983).

Mood

Beck Depression Inventory – Second Edition (BDI-II)

As one of the most widely accepted measures of depression, the BDI-II was utilised to monitor the presence and severity of mood symptoms (Beck et al., 1996). The BDI-II is a 21-item self-report questionnaire, with items corresponding to the criteria for the diagnosis of depression, as outlined in the American Psychiatric Associations Diagnostic and Statistical Manual of Mental Disorders – Fourth Edition (DSM-IV-TR, 2000). Items tap areas such as sadness, pessimism, past failure, loss of pleasure, guilty feelings, punishment feelings, self-dislike, self-criticalness, suicidal thoughts or wishes, crying, agitation, loss of interest, indecisiveness, worthlessness, loss of energy, changes in sleeping pattern, irritability, changes in appetite, concentration difficulty, tiredness or fatigue, and loss of interest in sex. Statements of varying severity are included under each of these areas, and participants are asked to choose the statement that best describes how they have been feeling in the past fortnight including today. Administration followed the standard administration procedures, as described by Beck et al. (1996).

Affect

Spielberger State-Trait Anxiety Inventory – Form Y (STAI)

With over 3000 studies and reviews reported in the literature and strong psychometric qualities, the STAI was chosen to assess state and trait anxiety in study population (Spielberger et al., 1983). This self-reported measure provides an indication of an individual’s general level of anxiety (or trait anxiety), along with an estimate of one’s emotional state during the assessment process (state anxiety). The participant is required to rate the frequency in which they experience feelings of apprehension, tension, nervousness, and worry either at the time of the assessment or in general. The STAI was administered in accordance with the guidelines provided in the STAI-Form Y manual (Spielberger et al).