Martin Kloss

Executive functioning in obsessive–compulsive disorder, unipolar depression, and schizophrenia

The present study investigated whether schizophrenic, unipolar depressive, and obsessive-compulsive psychiatric patients show a distinguishable profile in tasks considered sensitive to frontal lobe functioning. Three psychiatric samples, each comprising 25 patients with little symptomatic overlap, were compared to 70 healthy controls. Participants completed several executive tasks (Wisconsin Card Sorting Test (WCST), verbal fluency, digit span, Stroop, and Trail-Making). Except for age, which was entered as a covariate, subjects did not differ in any sociodemographic background variable. Healthy controls showed superior performance relative to depressive and schizophrenic patients who exhibited comparable deficits in all tasks. Obsessive-compulsive disorder (OCD) patients revealed dysfunctions in the Trail-Making Tests A and B and in the fluency task. Dysfunctions in the domains of working memory, verbal fluency, distractibility, and concept formation were not confined to a specific psychiatric population.

Symptom dimensions in obsessive–compulsive disorder: prediction of cognitive-behavior therapy outcome

Objective:  A significant number of patients with obsessive–compulsive disorder (OCD) fail to benefit sufficiently from treatments. This study aimed to evaluate whether certain OCD symptom dimensions were associated with cognitive‐behavioral therapy (CBT) outcome.

Impact of comorbid depressive symptoms on neuropsychological performance in obsessive-compulsive disorder.

There is indirect evidence from previous research that several executive disturbances in obsessive-compulsive disorder (OCD) are mediated by comorbid depressive symptoms. For the present study, the authors investigated whether OCD patients with elevated Hamilton Rating Scale for Depression (HRSD) scores would exhibit deficits in tasks sensitive to the medial and dorsolateral frontal cortex as well as other executive tasks. The 36 OCD patients were split along the median according to their HRSD scores and compared with matched control subjects. Patients with high HRSD scores performed significantly worse than control subjects and patients with low HRSD scores on the Wisconsin Card Sorting Test, the Trail-Making Test (TMT, Part B), and the TMT difference score. Moreover, patients with high HRSD scores exhibited deficits on a (creative) verbal fluency task. It is suggested that comorbid depressive symptoms may have artificially inflated some executive deficit scores in previous studies.

Dimensional structure of the Yale–Brown Obsessive-Compulsive Scale (Y-BOCS)

The Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) is a widely used instrument to assess obsessive-compulsive symptomatology. The present study provides evidence that the Y-BOCS is best represented by a three-dimensional model comprising severity of obsessions (factor 1), severity of compulsions (factor 2) and resistance to symptoms (factor 3). On the basis of exploratory factor analysis, this structure was found for both baseline (n = 109) and discharge ratings (n = 68) following a multimodal cognitive-behavioral intervention. The factor solution remained essentially unchanged when two optional items (items 1b and 6b) were dropped from analysis. The three-factor structure was replicated with confirmatory factor analysis and showed better fit than previously proposed single- and two-factor models. For future research, we propose a new Y-BOCS scoring algorithm that takes this factor structure into account. A further result was that resistance significantly declined in response to cognitive-behavioral intervention, whereas drug treatment alone did not seem to moderate this variable according to previous research conducted by Kim et al. [Psychiatry Research 51 (1994) 203-211].

Impact of comorbid depressive symptoms on nonverbal memory and visuospatial performance in obsessive-compulsive disorder.

Introduction. Recent research has suggested that some executive dysfunctions in obsessive-compulsive disorder (OCD) represent an epiphenomenon of comorbid depressive symptoms. The present study investigated whether the impact of comorbid depressive symptoms on cognitive dysfunction in OCD extends to nonverbal memory impairment. Methods. A total of 32 OCD patients and 20 healthy controls took part in the study. Participants were administered a neurocognitive battery with a focus on nonverbal memory and visuospatial functions. Results. While evidence was provided that neurocognitive processes necessitating visuospatial transformation and visuoconstruction are deficient in OCD patients regardless of comorbid depressive symptoms, nonverbal memory dysfunctions were only apparent for patients with elevated scores in the Hamilton Depression (HDRS) Rating Scale (total score S 8). Correlations with subscores of the HDRS revealed that core depressive symptoms are related to nonverbal memory deficits in OCD. Mental rotation, middle discrimination, and position discrimination were found to be unaffected in OCD. Y-BOCS scores, length of illness, onset of illness, number of hospital admissions, and checking compulsions were not associated with neurocognitive disturbances. Conclusions. Nonverbal memory is disturbed in only a subgroup of OCD patients displaying elevated HDRS scores (HDRS S 8). It is claimed but awaits further empirical testing that differences in depression profile across OCD studies have contributed to inconsistencies in prior investigations on neurocognitive functioning in OCD. Our results are questioning the hypothesis that nonverbal deficits are a causal factor for the development of checking compulsions.

Positive schizotypal symptoms predict treatment outcome in obsessive–compulsive disorder

Previous research has suggested that the presence of schizotypal personality disorder may represent a risk factor for treatment failure in obsessive-compulsive disorder (OCD). Relying on a dimensional approach, the present study investigated whether the predictive importance of schizotypal personality is shared by all of its features to the same extent or whether it is confined to a subset of symptoms. Fifty-three patients underwent multi-modal cognitive-behavioral therapy with or without adjunctive antidepressive medication. Therapy response was defined as a 35% decline of the Y-BOCS total score. At baseline assessment, patients were asked to fill out the schizotypal personality questionnaire, the perceptual aberration scale and the Beck depression inventory. Stepwise regression analysis and group comparisons conducted with the schizotypal and depression scales revealed that elevated scores in the positive schizotypal scales, especially perceptual aberrations, were highly predictive for treatment failure. Responders to treatment and non-responders did not significantly differ on other variables or on scores in two scales which measured response biases. The study provides evidence that positive schizotypal symptoms are antecendents for treatment failure in OCD. It needs to be evaluated whether these at-risk individuals benefit from additional intervention, such as the adminstration of low-dose atypical neuroleptics and specifically tailored behavorial intervention.

Examination of emotional Stroop interference in obsessive-compulsive disorder

Previous research has produced conflicting findings on whether or not patients with subclinical or manifest obsessive-compulsive disorder (OCD) share an attentional bias for anxiety-related material. In the present study, 35 OCD patients were compared with 20 healthy controls on their performance in an emotional Stroop paradigm. Nine different stimulus conditions were compiled, including sets for depression-related and anxiety-related words as well as stimuli from two constructs with a potential relevance for the pathogenesis and maintenance of OCD symptomatology: responsibility and conscientiousness. Patients did not show enhanced interference for any of the conditions. Syndrome subtype and severity, avoidance and speed of information processing did not moderate results. The present study concurs with most prior research that OCD patients display no interference effect for general threat words. It deserves further consideration, that emotional interference effects in OCD as seen in other anxiety disorders occur when using idiosyncratic word material with a direct relation to the individuals primary concerns.

Comparable performance of patients with obsessive-compulsive disorder (OCD) and healthy controls for verbal and nonverbal memory accuracy and confidence: time to forget the forgetfulness hypothesis of OCD?

The memory deficit or forgetfulness hypothesis of obsessive-compulsive disorder (OCD) has received considerable attention and empirical effort over the past decades. The present study aimed to provide a fair test of its various formulations: (1) memory dysfunction in OCD is ubiquitous, that is, manifests irrespective of modality and material; (2) memory dysfunction is found for nonverbal but not verbal material, (3) memory dysfunction is secondary to executive impairment; and (4) memory dysfunction affects meta-memory rather than memory accuracy. Participants comprised 43 OCD patients and 46 healthy controls who were tested on the Picture Word Memory Test (PWMT), which provides several unconfounded parameters for nonverbal and verbal memory accuracy and confidence measures across different time-points. In addition, the Trail-Making Test B was administered to test assumption number 3. Replicating earlier work of our group, samples displayed similar performance on all indices. None of the different formulations of the memory deficit hypothesis were supported. In view of waning evidence for a global memory deficit in OCD, neuropsychological research on OCD should more thoroughly investigate moderators and triggers of occasional instances of impaired performance, particularly cognitive biases such as perfectionism and an inflated sense of responsibility.

Extent, profile and specificity of visuospatial impairment in obsessive-compulsive disorder (OCD)

Recent reviews on the neurocognitive profile of patients diagnosed with obsessive-compulsive disorder (OCD) have converged on the assumption that both visuospatial and especially nonverbal memory performance are impaired in OCD. However, as most prior studies have contrasted performance of OCD patients with healthy controls only, no inferences can yet be drawn about the specificity of these deficits to OCD. Further, the administration of complex and multifunctional tasks limit conclusions about clearly defined cognitive deficits. The present study compared 71 OCD patients to 30 healthy and 33 psychiatric control participants on a large battery of visuospatial and nonverbal memory tasks at two time-points. In addition, a visuospatial battery (VS battery), which assesses a wide range of elementary visuospatial functions, was administered. While OCD patients performed worse than healthy controls on some complex tasks (e.g., Block Design), no visuospatial component proved to be impaired specifically in OCD. OCD patients and controls performed similarly on parameters of nonverbal memory. Regarding organizational strategy, OCD patients performed worse than healthy (but not psychiatric) control participants on two out of three Rey-figure trials (copy and immediate). It is suggested that prior research overestimated the severity and significance of visuospatial and nonverbal memory impairment in OCD. The authors would like to thank Dr. Michael Rufer, Dr. Angelique Mundt and Jürgen Orthmann for help with recruitment. The study was supported by a grant of the German Research Foundation (MO 969/1-1).

Negative priming (cognitive inhibition) in obsessive-compulsive disorder (OCD)

Cognitive disinhibition has been implicated in the pathogenesis of obsessive-compulsive disorder (OCD). Negative priming (NP) is regarded to tap into this function. While early studies indeed found reduced negative priming in OCD, attempts to replicate are both scarce and equivocal. Moreover, several studies in favor of the disinhibition hypothesis are plagued by methodological limitations. For the present investigation, 18 participants with OCD and 28 healthy controls underwent a computerized NP experiment with varying response-stimulus intervals. In addition, a variant of the paradigm with concurrent item presentation was employed to rule out the confounding impact of memory. Negative priming was comparable between groups yielding small between-group effect sizes. The present study challenges broad claims of disinhibition in OCD. In our view, the disinhibition account faces theoretical problems. Instead, theories implicating cognitive biases as well as metacognitive problems may more parsimoniously explain the idiosyncratic nature of OCD symptoms.