| Background: Psychiatrists found that patients with obsessive-compulsive disorder (OCD) had some problem of attention that they were more care about some special things and could not switch attention to another. It's a phenomenon of the disability of attention shifting which is a part of cognitive flexibility. There are some studies found that cognitive flexibility was a characteristic of patients with OCD. There are also studies found that attention set-shifting maybe a characteristic of OCD, though these results are debated. The cause of disaccord maybe is heterogeneity of OCD. The recent researches of psychiatry are focus on"endophenotype". The theory announced endophenotype is medial state between diseases and symptoms, includ abnormal of neurophysiology, biochemistry and behavior. It also include cognitive study. So, we considerate attention shifting impairment maybe the endophenotype in obsessive-compulsive disorder. Our study wants to explain the hypothesis from task-swiching paradigm test in patients with OCD and their unaffected first-degree relatives.Presently, researchers consider attention shifting function is relative with function of prefrontal-striatum circuit loop and biological activity of neurotransmitters of dopamine. Some researches found Catechol-O-Methyl-transferase (COMT) Val (108/158) Met polymorphism was relative with attention shifting function. Accordingly we took COMT gene for a candidate gene in this study, to complaint that attention shifting impairment may be an endophenotype in obsessive-compulsive disorder.Aims: The present study aimed to examine attention shifting function in patients with obsessive-compulsive disorder, their unaffected first-degree relatives and healthy controls with task-switch paradigm, and the relationship between attention shifting function and COMT gene polymorphism. Method:The study participants included 101 patients with OCD, 26 unaffected first-degree relatives and 90 healthy controls. All of the participants completed task-switch paradigm, sustained attention to response task, logical memory test, visual memory test, working memory test, word fluency test, modified Wisconsin card sorting test, stroop color-word test, Hayling sentence completion test, stop signal task and Intelligence Quotient test. The polymerase chain reaction was used to detect the genotype of COMT gene in all participants.Results:1) The results showed that patients with OCD were impaired in task-switch paradigm in the condition of repeat-react time and switch-react time (P<0.05). The two groups had significated difference in logical delay memory (P<0.05), and no significated difference in visual memory and working memory. The difference in inhibiton function between two groups is no signification. In the aspect of executive function, there are significant difference in word fluency test (F=5.13, P=0.025) and modified Wisconsin card sorting test (F=4.72, P=0.031) between two groups. The difference between two groups is border in sustained attention to response task (P=0.049, ?2=0.02).2) The result of attention shifting and other cognitive tests in three groups is that patients with OCD were worse than unaffected first-degree relatives, relatives were worse than controls. There were significant difference of three groups in attention shifting under repeat-react time condition (P<0.01) The difference of attention shifting function under switch-react time condition in three groups is border (P=0.059, ?2=0.09). In sustained attention to response task, the react time was sifnificant in three groups (P<0.05). In the aspect of executive function, the difference of modified Wisconsin card sorting test was significant (P<0.01) in three groups. No significant difference was found in memoty funcion, inhibition function and word fluency test.3) The result was there was no significant difference in COMT gene Val158Met polymorphism between controls and patients with OCD. About the samples of study one, there was significant difference of each genotype in word fluency test about (P<0.05), and Met/Met individuals had the highest error rate. In controls there was no significant difference in cognitive function tests between each genotype (P>0.10). In the samples of study two, there are no significant difference in cognitive function tests (attention shifting repeat-react time, attention shifting repeat-react time, and sustained attention to response task react time, word fluency test-correct, WCST-PE, WCST-category) between each genotype.Conclusions: The model attention shifting function in patients with OCD and unaffected first-degree relatives is (from worse to better): patients, first-degree relatives, controls. The performance of other cognitive function test (memory, sustained attention, inhibition function, executive function) in patients with OCD and unaffected first-degree relatives from worse to better is patients, first-degree relatives, controls. Attention shifting function in patients with OCD is related with genetics, but not COMT gene polymorphism. |
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