Resumo

TIRADO DURAN, Elsa; RICARDO-GARCELL, Josefina; REYES ZAMORANO, Ernesto  e  LOYZAGA MENDOZA, Cristina. Neuropsychological characterization in clinical subtypes of an Obsessive-Compulsive Disorder (OCD) sample of patients. Salud Ment [online]. 2007, vol.30, n.1, pp.1-8. ISSN 0185-3325.

Since the decade of the seventies, several neuropsychological abnormalities in very different cognitive domains have been described among patients with Obsessive-compulsive disorder (OCD). Due to the nature of these abnormalities, it was concluded that possibly the main dysfunction for this disorder was located in the right hemisphere, especially in the frontal cortex; nevertheless this particular brain region was found to be involved in other psychiatric disorders, so neuropsychological results were considered to be of limited precision and it was thought that the diversity in results was not due to the malfunction of one particular brain region.

So it became evident that a new research methodology based in the information processing model with highly specific neuropsychological paradigms of frontal functioning was needed; as well as considering a subtypology based in the cognitive characteristics in patients with the same disorder and similar phenomenology.

Regarding OCD it is well known that the dorsolateral prefrontal cortex is in charge of the regulation of complex actions, executive functions and the elaboration of logical strategies in a problem solving task; so its dysfunction causes a failure in the creation of response patterns and perseverations due to the inability to change a pattern when an alternative response is needed.

On the other hand, obsessions are associated mainly with the anterior cingulated cortex and the basal region of the corpus striatum and its connections with the limbic system, giving place to incapacity to select the relevant information from the environment, which makes the individual perceive irrelevant stimuli as threatening for physical integrity.

By the way, some clinical subtypes have also been identified: contamination/washing, aggressiveness/checking, hoarding, symmetry/ order. There is also some evidence of different patterns of brain activation to several visual stimuli related to the obsessive or compulsive object in the clinical subtypes, as shown by functional magnetic resonance image in some regions of the frontal lobe, either dorsolateral, medial or basal and its connections with the basal ganglia, and in some cases thalamus or limbic system.

In the face of all this evidence, the goal of the present study was to find if within this disorder it was possible, through several neuropsychological paradigms of frontal functioning, to find different patterns of execution, considering the clinical subtype and the severity of obsessions and compulsions.

Fifty-eight patients with a diagnosis of OCD were studied; all patients were under treatment at the OCD clinic of the National Institute of Psychiatry Ramón de la Fuente in Mexico City. Two neuropsychological tests were administered: 1) Trail Making Test (TMT) and 2) Wisconsin Card Sorting Test (WCST). From the Target Symptom List, the clinical subtype was obtained.

After the statistical analysis, we found no differences between the severity of obsessions and the severity of compulsions as measured by the Yale-Brown Scale. Also, we observed three factors concerning the neuropsychological tests, and patients were grouped in four different groups, each one with a distinct cognitive performance.

Through the interpretation of results it was concluded that in a sample of 58 patients with OCD, different groups of neuropsychological functioning where distinguished. In their own, these groups where associated with different clinical subtypes. These results are in accordance with the neurobiological modular organization model of OCD, which sustains the existence of independent systems of cognitive dysfunction that regulate different symptomatic expressions.

Palavras-chave : Obsessive-compulsive disorder; Wisconsin Card Sorting Test; Trail Making Test; OCD clinical subtypes; Yale-Brown Severity Scale.

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