The influence of serotonin transporter polymorphisms on cortical activity: A resting EEG study
1 Department of Psychiatry, Chang Gung Memorial Hospital, Taoyuan County, Taiwan
2 College of Medicine, Chang Gung University, Taoyuan County, Taiwan
3 Yu's Psychiatric Clinic, Kaohsiung, Taiwan
4 Department of Psychiatry, Taipei Veterans General Hospital, Taipei, Taiwan
5 School of Medicine, National Yang-Ming University, Taipei, Taiwan
6 Kai-Suan Psychiatric Hospital, Kaohsiung, Taiwan
7 Department of Psychiatry, E-DA Hospital, Kaohsiung County, Taiwan
8 Department of Occupational Therapy, I-Shou University, Kaohsiung County, Taiwan
BMC Neuroscience 2011, 12:33 doi:10.1186/1471-2202-12-33Published: 20 April 2011
The serotonin transporter gene (5-HTT) is a key regulator of serotonergic neurotransmission and has been linked to various psychiatric disorders. Among the genetic variants, polymorphisms in the 5-HTT gene-linked polymorphic region (5-HTTLPR) and variable-number-of-tandem-repeat in the second intron (5-HTTVNTR) have functional consequences. However, their genetic impact on cortical oscillation remains unclear. This study examined the modulatory effects of 5-HTTLPR (L-allele carriers vs. non-carriers) and 5-HTTVNTR (10-repeat allele carriers vs. non-carriers) polymorphism on regional neural activity in a young female population.
Blood samples and resting state eyes-closed electroencephalography (EEG) signals were collected from 195 healthy women and stratified into 2 sets of comparisons of 2 groups each: L-allele carriers (N = 91) vs. non-carriers for 5-HTTLPR and 10-repeat allele carriers (N = 25) vs. non-carriers for 5-HTTVNTR. The mean power of 18 electrodes across theta, alpha, beta, gamma, gamma1, and gamma2 frequencies was analyzed. Between-group statistics were performed by an independent t-test, and global trends of regional power were quantified by non-parametric analyses.
Among 5-HTTVNTR genotypes, 10-repeat allele carriers showed significantly low regional power at gamma frequencies across the brain. We noticed a consistent global trend that carriers with low transcription efficiency of 5-HTT possessed low regional powers, regardless of frequency bands. The non-parametric analyses confirmed this observation, with P values of 3.071 × 10-8 and 1.459 × 10-12 for 5-HTTLPR and 5-HTTVNTR, respectively.
Conclusions and Limitations
Our analyses showed that genotypes with low 5-HTT activity are associated with less local neural synchronization during relaxation. The implication with respect to genetic vulnerability of 5-HTT across a broad range of psychiatric disorders is discussed. Given the low frequency of 10-repeat allele of 5-HTTVNTR in our research sample, the possibility of false positive findings should also be considered.