Increased brain activity to unpleasant stimuli in individuals with the 7R allele of the DRD4 gene

The aim of the study was to examine functional brain activity in response to unpleasant images in individuals with the 7-repeat (7R) allele compared to individuals with the 4-repeat (4R) allele of the dopamine receptor D4 (DRD4) gene (VNTR in exon 3). Based on the response ready hypothesis, individuals with the DRD4-4R/7R genotype were expected to show greater functional brain activity in response to unpleasant compared to neutral stimuli in specific regions of the frontal, temporal, parietal and limbic lobes, which form the networks involved in attentional, emotional, and preparatory responses. Functional Magnetic Resonance Imaging activity was studied in 26 young adults (13 with the DRD4-4R/7R genotype and 13 with the DRD4-4R/4R genotype). Participants were asked to look at and subjectively rate unpleasant and neutral images. Results showed increased brain activity in response to unpleasant images compared to neutral images in the right temporal lobe in participants with the DRD4-4R/7R genotype versus participants with the DRD4-4R/4R genotype. The increase in right temporal lobe activity in individuals with DRD4-4R/7R suggests greater involvement in processing negative emotional stimuli. Intriguingly, no differences were found between the two genotypes in the subjective ratings of the images. The findings corroborate the response ready hypothesis, which suggests that individuals with the 7R allele are more responsive to negative emotional stimuli compared to individuals with the 4R allele of the DRD4 gene.

Dopamine receptor gene d4 polymorphisms and early sexual onset: gender and environmental moderation in a sample of african-american youth

PURPOSE

Early sexual onset and its consequences disproportionately affect African-American youth, particularly male youth. The dopamine receptor D4 gene (DRD4) has been linked to sexual activity and other forms of appetitive behavior, particularly for male youth and in combination with environmental factors (gene × environment [G × E] effects). The differential susceptibility perspective suggests that DRD4 may exert this effect by amplifying the effects of both positive and negative environments. We hypothesized that DRD4 status would amplify the influence of both positive and negative neighborhood environments on early sexual onset among male, but not female, African-Americans.

METHODS

Hypotheses were tested with self-report, biospecimen, and census data from five prospective studies of male and female African-American youth in rural Georgia communities, N = 1,677. Early sexual onset was defined as intercourse before age 14.

RESULTS

No significant G × E findings emerged for female youth. Male youth with a DRD4 long allele were more likely than those with two DRD4 short alleles to report early sexual onset in negative community environments and not to report early onset in positive community environments.

CONCLUSIONS

Dopaminergic regulation of adolescent sexual behaviors may operate differently by gender. DRD4 operated as an environmental amplification rather than a vulnerability factor.

Factors associated with sexual arousal, sexual sensation seeking and sexual satisfaction among female African American adolescents

BACKGROUND

Sexuality-related constructs, such as sexual arousal, sexual sensation seeking (SSS) and sexual satisfaction, have been related to sexual behaviours that place one at risk of adverse consequences, such as sexually transmissible infections, HIV and unintended pregnancy. The biopsychosocial model posits an array of factors, ranging from social environmental factors to biological and psychological predispositions, that may be associated with these sexuality constructs in adolescents.

METHODS

Female African Americans aged 14-20 years were recruited from reproductive health clinics for an HIV intervention. Baseline survey and follow-up DNA data (n=304) were used to assess biological, psychological and social environmental associations with the sexuality constructs of arousal, SSS and sexual satisfaction.

RESULTS

Multivariate linear regression analysis revealed that a higher depressive symptom rating was associated with higher arousability, whereas short serotonin transporter gene allele(s) status was associated with lower arousability. Impulsivity and perceived peer norms supportive of unsafe sexual behaviours were associated with increased SSS, whereas short serotonin transporter gene allele(s) status was associated with lower SSS. Higher social support was associated with higher levels of sexual satisfaction, whereas short serotonin transporter gene allele(s) status was associated with lower satisfaction. The sexuality constructs were also significantly related to the number of sex partners, the frequency of vaginal sex and the number of unprotected vaginal sex acts in the past 6 months.

CONCLUSIONS

The findings emphasise the importance of understanding biopsychosocial factors, including the role of serotonin as an indicator of natural variations in sexual inclination and behaviours, that influence sexuality constructs, which, in turn, are associated with sexual behaviours, to allow further refinement of sexual health clinical services and programs and promote the development of healthy sexuality.

Evaluation and treatment of sex addiction

There have been several diagnostic labels for persistent, excessive sexual behaviors, often referred in the popular media as sex addiction. Two related diagnoses, Internet addictive disorder and hypersexual disorder, were considered for, but not included in the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders. However, most clinicians, even those trained in sexual disorders or addiction medicine, have little to no training in treating sexual compulsivity and cybersex addiction. The authors present the historical context, proposed diagnostic criteria, evaluation protocols, comorbid disorders, speculations about the neuroscience, and treatment recommendations.

Genetic sensitivity to peer behaviors: 5HTTLPR, smoking, and alcohol consumption

We investigate whether the serotonin transporter-linked polymorphic region (5HTTLPR), a gene associated with environmental sensitivity, moderates the association between smoking and drinking patterns at adolescents' schools and their corresponding risk for smoking and drinking themselves. Drawing on the school-based design of the National Longitudinal Study of Adolescent Health in conjunction with molecular genetic data for roughly 15,000 respondents (including over 2,000 sibling pairs), we show that adolescents smoke more cigarettes and consume more alcohol when attending schools with elevated rates of tobacco and alcohol use. More important, an individual's susceptibility to school-level patterns of smoking or drinking is conditional on the number of short alleles he or she has in 5HTTLPR. Overall, the findings demonstrate the utility of the differential susceptibility framework for medical sociology by suggesting that health behaviors reflect interactions between genetic factors and the prevalence of these behaviors in a person's context.

The effect of life expectancy on aggression and generativity: a life history perspective

Following a model that is inclusive of both dispositional and situational influences on life-history behaviors and attitudes, the effect of life expectancies on aggression and generativity was examined. Consistent with the hypotheses it was found that shorter life expectancies led to an increase in the desire to aggress and a decrease in the desire to engage in generative behaviors. The results are discussed in terms of how life history theory can be used to frame research on person-situation interactions.

Assortative human pair-bonding for partner ancestry and allelic variation of the dopamine receptor D4 (DRD4) gene

The 7 repeat (7R) allele of the dopamine receptor D4 gene has been associated with attention deficit hyperactivity disorder and risk taking. On the cross-population scale, 7R allele frequencies have been shown to be higher in populations with more of a history of long-term migrations. It has also been shown that the 7R allele is associated with individuals having multiple ancestries. Here, we conduct a replication of this latter finding with two independent samples. Measures of subjects' ancestry are used to examine past reproductive bonds. The individuals' history of interracial/ancestral dating and their feelings about this are also assessed. Tentative support for an association between multiple ancestries and the 7R allele was found. These results are dependent upon the method of questioning subjects about their ancestries, with only finer-scale measures of ancestry being associated with 7R. Interracial dating and feelings about interracial pairing were not related to the presence of the 7R allele. This study provides continued support for a role for the 7R allele in migration and/or mate choice patterns. However, replications and extensions of this study are needed and the way ancestry/race is assessed must be carefully considered.