Gyula Demeter

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2.3. Impairment of executive functions in OCD According to recent findings, the primary cognitive deficit contributing to the OCD profile is dysfunction of the executive system (Olley, Malhi, & Sachdev, 2007). However, many studies have found less impaired or intact performance in traditional executive neuropsychological tasks for OCD patients (for reviews, see Greisberg & McKay, 2003; Kuelz, Hohagen, & Voderholzer, 2004; Chamberlain, Blackwell, Fineberg, Robbins, & Sahakian, 2005; in Hungarian <strong>Demeter</strong>, Csigó, Harsányi, Németh, & Racsmány, 2008; <strong>Demeter</strong>, 2010). In this overview the most relevant research findings from this field are presented using the Miyake et al. (2000) psychometric model about executive functions. According to this approach, traditional neuropsychological executive tasks depend on three main central executive components: modality-specific updating/monitoring, shifting and inhibition. The authors used confirmatory factor analyses and structural equation modeling to find evidence supporting the unity and diversity of executive functions, and for this have preselected well known simple executive tasks (e.g., plus-minus task, stop-signal task, number-letter task etc.) which were considered to tape the above mentioned 3 main components of the executive system, as well as complex executive tasks as the WCST, the Tower of Hanoi, the random number generation and the dual tasking. The three latent variables were correlated but separable and contributed in different proportions to the performance on complex executive tasks. By structural equation modeling they find evidence supporting that WCST was related especially to shifting, the Tower of Hanoi to inhibition and the random number generation to updating executive functions. In the overview below we will focus on these 3 main components and we will not discuss the results from other main executive domains as planning, problem solving and decision making. Updating and monitoring This component refers to refreshing the content of the working memory. Maintenance of task-relevant information is accomplished by monitoring and coding relevant incoming information, and replacing old information that is no longer task-relevant (Morris & Jones, 1990). The importance of updating is that it actively manipulates relevant information in the working memory, rather than passively storing information (Miyake et al., 2000). 14
The tasks that are most commonly used to test this function in the OCD literature are the Letter Fluency Task (e.g., Martinot et al., 1990), the Letter Memory Task (e.g., Morris and Jones, 1990), and the N-back Task (e.g., van der Wee et al., 2003). OCD patients usually perform poorly in the latter two tasks while the results regarding verbal fluency are more contradictory. The test which has been used the most often to study lexical fluency in OCD is the Controlled Oral Word Association Test (COWAT) which requires from the subjects to generate in one minute as many words as they can with the given starting letter (e.g., F, A, S) following certain simple rules (e.g., cannot use proper names, inflections, repetitions). Just a few studies report reduced lexical fluency (Christensen, Kim, Dysken, & Hoover, 1992; Schmidtke, Schorb, Winkelmann, Hohagen, 1998) most studies find this capacity intact in OCD (Martinot et al., 1990; Zielisnki, Taylor, & Juzwin, 1991; Pujol et al., 1999; Jurado, Junqué, Vallejo, & Salgado, 2001; Basso, Bornstein, Carona, & Morton, 2001; Spitznagel & Suhr, 2002; Roh et al., 2005). It is important to note that the time span used in different letter fluency task was some time different, making comparison of the results difficult. For example Zielinski et al. (1991) used a 5 minute period, while in the Sieg et al. (1999) study only one minute was given for each letter. In contrast, some studies find low performance in semantic verbal fluency tasks, where subjects have to generate words from a predefined category in on minute (e.g., animals, fruits, vegetables) (Lacerda et al., 2003; Roh et al., 2005). This result may reflect reduced access to the semantic system in OCD (Olley et al., 2007). While there is an impressive amount of data (for review see Kuelz et al, 2004) about impaired visual ability and visuospatial organization in OCD there are just a couple of non- verbal fluency studies using very different tasks and scoring techniques. Some report deficit (Schmidtke et al., 1998; Mataix-Cols, Barrios, Sánchez-Turet, Vallejo, & Junque, 1999), the others stand by intact functioning in OCD (e.g., Christensen et al., 1992). From all these studies we can conclude that OCD patients have difficulties in semantic fluency tasks probably due to an accessibility problem but they perform in the normal healthy range regarding letter and design fluency. In future studies in this domain near the inclusion of a perfectly matched healthy control group (education, IQ, gender, handedness, no previous psychiatric diagnoses) a clinical control group will be very useful to help clarifying the specificity of the neuropsychological dysfunction in OCD. 15
Page 1 and 2: Budapest University of Technology a
Page 3 and 4: 6.3. Study 3: Over-monitoring secon
Page 5 and 6: Glossary of abbreviations ACC Anter
Page 7 and 8: WCST-LS Wisconsin Card Sorting Task
Page 9 and 10: Kivonat Az obszesszív-kompulzív z
Page 11 and 12: Introduction In our daily life we r
Page 13 and 14: Chapter 1. Overview of Obsessive co
Page 15 and 16: ilaterally at the ventromedial pref
Page 17 and 18: Chapter 2. The study of executive f
Page 19 and 20: 2.2. Theories and measurement of ex
Page 21 and 22: outcomes etc.) which in many labora
Page 23: As far as we know no executive task
Page 27 and 28: 2002) and on the Intra-Dimensional/
Page 29 and 30: Inhibition In the Miyake et al. (20
Page 31 and 32: Table 1. Summary of OCD patients re
Page 33 and 34: Authors Samples Medication Performa
Page 35 and 36: Chapter 3. The study of memory func
Page 37 and 38: 3.2. Prospective memory Prospective
Page 39 and 40: 3.2.1. Theories of prospective memo
Page 41 and 42: According to Guynn (2008) retrieval
Page 43 and 44: intention or the initiation and exe
Page 45 and 46: 3.2.3. Studying PM in OCD While at
Page 47 and 48: 3.2.4. A possible PM model of OCD O
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Page 53 and 54: it, (3) the neuropsychological impa
Page 55 and 56: 4.3. Current neurobiological model
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Page 59 and 60: 5.1. Main goals 1. To assess the le
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Page 63 and 64: impairment in this task 15 and othe
Page 65 and 66: Procedure All OCD patients received
Page 67 and 68: series of equal length, and we cons
Page 69 and 70: called error inhibition index (SEII
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REFERENCES 1. American Psychiatric
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20. van der Wee NJ., Ramsey NF, Jan
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39. Goodman WK, Price LH, Rasmussen
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6.2. Study 2: Impaired prospective
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Table 1 Sample demographics and bas
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Written instructions were read to t
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Table 2 Hit rate in the two experim
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Comparison of patient and healthy a
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can be concluded that OCD patients
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6.5. Study 5: No retrieval induced
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Experimental design and materials T
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Procedure “In the study phase, pa
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RIF effect in the control group, t(
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Chapter 7. Discussion, conclusions
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and retrospective memory processes
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Gyula Demeter

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