Relationship Between 5-HTTLPR Gene Polymorphism And Brain Function And Cognitive Function In Adolescents With First-episode Major Depressive Disorder

Background Major depressive disorder(MDD),which is a serious mental disease,has a high prevalence,recurrence rate,disability rate,suicide rate.Cognitive dysfunction is common in patients with MDD.The prevalence of MDD is increasing year by year,and cognitive impairment will seriously affect the social function and mental development of adolescents.Further development of functional imaging genetics in recent years provides a new idea for the research of MDD.Most of the genetic studies on MDD mainly in adult patients,including the relationship between brain structure and single nucleotide polymorphism.,5-serotonin pathway related genes are targets of imaging genetics research widely,found that MDD patients with different 5-HTTLPR allele carriers have differences in brain structure and function.But MDD often occurs in adolescence,the brain and the network development particularity is not mature in adolescence.The neurobiological processes of the same psychiatric disorders in adults and adolescents are different.Therefore,it fully demonstrates the importance of the study of cognitive function and imaging genetics in adolescents with MDD.Objective 1 To analyze the relationship between 5-HTTLPR gene polymorphism and clinical features and cognitive dysfunction in adolescents with MDD;2 To investigate whether there is abnormal resting state brain function in adolescents with MDD;3 To investigate whether the 5-HTTLPR gene polymorphism is involved in the regulation of resting state brain function in adolescents with MDD.Methods 76 cases in line with "The Diagnostic and Statistical Manual of Mental Disorders"(4th edition,DSM-IV)diagnostic criteria for MDD in patients with first-episode adolescent MDD and 73 normal controls.Polymerase chain reaction(PCR)amplification technology for 5-HTTLPR gene typing,using the Wisconsin Card Sorting Test(WCST)and connection test(TMT)for cognitive function testing,using Hamilton Depression Scale(HAMD24)scoring clinical symptom.The clinical symptoms and cognitive function of patients with different genotypes of 5-HTTLPR were compared;Then the resting state functional magnetic resonance imaging(f MRI)scan,because of the degree of restriction,into the group of f MRI analysis,including 48 cases of adolescent MDD,23 cases of adolescent controls.The f MRI data of 71 subjects in the study were analyzed,and the ALFF value was calculated.Finally,the ALFF values of different genotypes and different age groups were compared.Results 1 Relationship between 5-HTTLPR gene polymorphism and clinical features and cognitive dysfunction in adolescents with MDD: 1.1 Aleep scores of case group with S/S type were significantly higher than those of case group with type L allele carrying(χ2=10.376,p=0.006);agitation scores of case group with S/S type were significantly higher than those of case group with type L allele carrying(χ2=15.789,p=0.000);Inferiority scores of case group with S/S were significantly lower than those of case group with type L allele carrying(χ2=7.827,p=0.020);1.2 There is no significant difference in cognitive function among group S/S、groupL allele carrying.2 ALFF results 2.1 Comparison of ALFF values between case group and control group ALFF values in the left superior frontal gyrus and left anterior cingulate cortex were significantly increased;they were significantly decreased in the caudate nucleus in adolescents with MDD than that in control;2.2 Comparison of ALFF values between different genotype and control group Compared with S/S type control group,the ALFF values of the S/S type case group in left anterior lobe of cerebellum,left frontal gyrus,right middle frontal gyrus,and right anterior cingulate gyrus were significantly increased,and the ALFF values in left precuneus and right angular gyrus were significantly reduced.Compared with L allele carrying type control group,the ALFF value of the S/S type case group in left middle frontal gyrus was significantly reduced.Conclusions 1 There is association between 5-HTTLPR gene polymorphism and clinical characteristics in adolescents with MDD.Type S/S patients may be prone to sleep problems and irritability;type L allele carrying patients may be prone to inferiority.There may be no direct association between 5-HTTLPR gene polymorphism and cognitive function dysfunction in adolescents with MDD.2 There were abnormal resting brain function ALFF values in some brain regions in adolescents with MDD,mainly concentrated in the frontal lobe,cingulate gyrus,caudate nucleus and other regions.3 5-HTTLPR gene polymorphisms may be relevant to the abnormal function of some brain regions in resting state of adolescent MDD.