Issues surrounding the cognitive neuroscience of obsessive-compulsive disorder

Threat processing in obsessive-compulsive disorder: evidence from a modified negative priming task

Individuals with obsessive-compulsive disorder (OCD) often experience intrusive thoughts. These intrusions may be due to biases in information processing mechanisms, including attention, memory, and learning. To examine this hypothesis, we presented a modified negative priming (NP) paradigm with idiographically selected words to 19 individuals with OCD (OCs) and 19 matched non-anxious control participants (NACs). The words included OCD-relevant threat, OCD-relevant positive, and neutral words. This paradigm typically elicits positive priming because participants may learn the contingency between the prime and probe that facilitates responding [Frings and Wentura (2006). Strategy effects counteract distractor inhibition: NP with constantly absent probe distractors. Journal of Experimental Psychology: Human Perception and Performance, 32, 854-864]. As predicted, NACs showed facilitation (i.e., positive priming) rather than NP for all word types, whereas OCs exhibited facilitation for only neutral words. For positive words, OCs exhibited no priming and for threat words they exhibited NP. These results suggest that for idiographic, OCD-relevant threat information, individuals with OCD show difficulty learning the contingency between the information in the prime and probe displays relative to the NACs.

Obsessive–compulsive disorder patients display enhanced latent inhibition on a visual search task

Latent inhibition (LI) is a phenomenon that reflects the ability to ignore irrelevant stimuli. LI is attenuated in some schizophrenic patient groups and in high schizotypal normal participants. One study has found enhanced LI in patients with obsessive-compulsive disorder (OCD [Swerdlow, N. R., Hartston, H. J., & Hartman, P. L., 1999. Enhanced visual latent inhibition in obsessive-compulsive disorder. Biological Psychiatry, 45, 482-488]). The present experiment replicated this finding using a within-subject visual search LI task, with OCD patients displaying more LI than healthy controls. The contrasting LI effects in schizophrenia and OCD are discussed in terms of how these groups differentially process relevant and irrelevant stimuli, and how that outcome affects subsequent behavior.

Impaired prepulse inhibition of acoustic startle in obsessive-compulsive disorder

BACKGROUND

Animal and clinical studies suggest that impaired sensorimotor gating, as assessed with the prepulse inhibition (PPI) paradigm, may result from dysfunctional frontostriatal brain circuits and from neurochemical alterations which are also implied in the pathophysiology of obsessive-compulsive disorder (OCD). However, there is only preliminary evidence about impaired PPI in OCD so far.

METHODS

Acoustic PPI was measured in 30 OCD patients and 30 matched healthy controls with a paradigm using different prepulse intensities. Psychopathology assessment included ratings for obsessions, compulsions, and depression.

RESULTS

PPI was reduced in OCD patients, and this deficit was most pronounced for most intense (16 dB(A)) prepulses, where mean PPI was 39.6% in unmedicated patients (n = 4), 45.8% in medicated patients, and 58.9% in controls. No group differences were observed with regard to the habituation of acoustic startle magnitude. Startle measures were generally not associated with clinical measures, although such associations may have been obscured by medication effects.

CONCLUSIONS

The present study confirms deficient central inhibitory functioning in patients with OCD and supports the model of deficient frontostriatal circuits in OCD. The relationship of PPI deficits to pharmacological and behavioral treatment and to possible subtypes of OCD merits further study.

A goal activation approach to the study of executive function: An application to antisaccade tasks

We argue that a general control process, responsible for the activation and maintenance of task goals, is central to the concept of executive function. Failures of this process can become manifest as goal neglect: disregard of a task requirement even though it has been understood (Duncan, 1995). We discuss the results of several published and new experiments using various versions of the antisaccade task in order to investigate the circumstances under which goal neglect is likely to occur. Potentially conflicting results in the literature on adaptive control of saccadic eye movements are argued to be attributable to the extent to which different task versions elicit goal neglect. The results suggest an increased susceptibility to goal neglect of high-functioning older adults (Experiment 1) and of first-episode schizophrenia patients (Experiment 2), but not of patients with obsessive-compulsive disorder (Experiment 3). However, the degree to which such differences in susceptibility become manifest in task performance, is shown to be strongly influenced by manipulations of the relative saliency of task requirements. Theoretical and methodological implications for the study of executive function are discussed.

Obsessive-compulsive symptoms in patients with temporal lobe epilepsy

The goals of this work were to: (1) determine the prevalence of clinically significant obsessive-compulsive (OC) symptoms in patients with temporal lobe epilepsy (TLE), (2) characterize the differences in self-reported OC symptoms in patients with TLE and a normative control group, and (3) compare the severity of OC symptoms in right and left hemisphere TLE patients. Patients with TLE (n=30) were administered the Obsessive-Compulsive Inventory (OCI). As a group, patients with TLE had a higher prevalence of OC symptoms than the nonpatient normative sample. In addition, TLE patients exhibited elevated scores on all but 3 of the 16 OCI scales and subscales. There were no reliable differences in OC symptoms in patients with right versus left hemisphere seizure foci, although the right hemisphere patients tended to score higher on both scales of the OCI.

Executive function in traumatic brain injury and obsessive-compulsive disorder: an overlap?

Thirteen individuals with traumatic brain injury, 13 individuals with obsessive-compulsive disorder (OCD) and 10 normal controls were compared on neuropsychological measures of executive function. Individuals with a traumatic brain injury performed significantly poorer than the other two groups on a test measuring visuo-spatial strategy. Although the traumatic brain injury group made more errors on a test of maze learning and the OCD group less than the control group, this did not reach statistical significance. No support for an overlap in executive dysfunction in traumatic brain injury and OCD was found. It may be that the 'error prevention system' in the brain was influenced in a contrasting way by executive dysfunction in these disorders. This difference may reveal itself clinically in impulsivity/perseveration and slowness, respectively. Further studies were needed to test this hypothesis.

The neurodevelopmental frontostriatal disorders: evolutionary adaptiveness and anomalous lateralization

The frontostriatal system (dorsolateral prefrontal cortex, lateral orbitofrontal cortex, anterior cingulate, supplementary motor area, and associated basal-ganglia structures) is subject to a range of neurodevelopmental disorders: Tourette's syndrome (TS), obsessive compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), schizophrenia (SCZ), autism, and probably depression. The system is responsible for our adaptive responses (initiation, execution, or withholding) to environmental situations, and the above disorders, involving effectively excessive release or withholding of various types of response, are all a consequence of changes in specific frontostriatal regions. The disorders all have a genetic component, and their persistence in the genome indicates that their clinical manifestations may also be associated, perhaps in low levels in close relatives, with certain adaptive advantages in given situations. Thus autism is associated with computational careers, depression with literary creativity, SCZ with lateral thinking and the Odyssean personality, ADHD with an Ice-Age readiness to respond, OCD with a focused range of interests, and TS with competitive sports and jazz improvisation. The disorders are all highly comorbid, and which one predominantly manifests may depend on how the frontostriatal system happens to be compromised as a result of inherited genetic predispositions and environmental contingency. We review the adaptive nature of the various subclinical manifestations and the evidence for concomitant phenomena (possibly epiphenomena): alterations in structural, functional, and behavioral lateralization in each syndrome. Indeed it is not clear that altered lateralization in frontostriatal disorders of a neurodevelopmental origin generally has any adaptive significance; it may often simply serve as a marker for altered regulatory function of the frontostriatal system, alterations which in low genetic dosage or penetrance continue to play an adaptive role in clinically unaffected close relatives of probands, but which, in high dosage or penetrance in the probands themselves, are generally deleterious.