Interactive effect of 5-HTTLPR genotype and age on sources of cortical rhythms in healthy women

- Difference in sources of cortical rhythm between young and older women is associated with 5-HTTLPR genotype.
- In S′/S′ less magnitude of all but beta2 and gamma sources in the posterior areas in OW than in YW
- In L/L genotype delta rhythm sources in the posterior areas had less magnitude in OW.
- In S′/L genotype beta1 sources in the frontal-temporal area had less magnitude in YW.
- More widespread age related changes in the right hemisphere in S′/S′ and L/L and in the left in S′/L

This study was aimed to localize the effects of 5-HTTLPR (serotonin-transporter-linked polymorphic region) on the age differences of spontaneous EEG activity in women using neuroimaging analysis sLORETA (Standardized Low Resolution brain Electromagnetic Tomography). DNA samples extracted from cheek swabs and resting-state EEG recorded at 60 standard leads were collected from young (YW, N = 86, 18-35 years) and older (OW, N = 45; 55-80 years) healthy women. We have shown that advanced age was associated with increased posterior EEG desynchronization in S′/S′. S′ (LG allele was grouped with S alleles owing to its functional equivalence and this group was labeled as S′) genotype carriers denoted by decrease of delta - beta1 current source density, and to a lesser extent in L/L homozygotes denoted by decrease in delta activity. In heterozygotes OW, as compared with heterozygotes YW, higher source density estimates of beta1 in frontal and temporal cortex were observed. Age differences were more pronounced in the right hemisphere in S′/S′ and L/L carriers and in the left hemisphere in heterozygotes. We also found that in OW, current source density estimates of theta, alpha1, alpha2, alpha3 and beta1 sources in the right occipital lobe were higher in S′/L than in S′/S′ carriers. These results may have implications for understanding 5-HTT-dependent variation in the effect of aging on brain activity.