Prospects for finding the mechanisms of sex differences in addiction with human and model organism genetic analysis

Substance Use Disorders in Women

Substance use disorder (SUD) is among the leading causes of premature morbidity and mortality and imposes significant health, economic, and social burdens. Gender differences have been found in the development, course, and treatment of SUD, with women at increased risk for physiologic and psychosocial consequences compared with men. Reasons for these differences are multifold and include biological, genetic, environmental, and behavioral factors. This article discusses SUD among women, emphasizing clinical considerations for care. Specific topics include epidemiology, sex and gender differences, common comorbidities, screening, diagnosis, treatment, pregnancy, and sociocultural factors.

Sex similarities and dopaminergic differences in interval timing

Rodent behavioral studies have largely focused on male animals, which has limited the generalizability and conclusions of neuroscience research. Working with humans and rodents, we studied sex effects during interval timing that requires participants to estimate an interval of several seconds by making motor responses. Interval timing requires attention to the passage of time and working memory for temporal rules. We found no differences between human females and males in interval timing response times (timing accuracy) or the coefficient of variance of response times (timing precision). Consistent with prior work, we also found no differences between female and male rodents in timing accuracy or precision. In female rodents, there was no difference in interval timing between estrus and diestrus cycle stages. Because dopamine powerfully affects interval timing, we also examined sex differences with drugs targeting dopaminergic receptors. In both female and male rodents, interval timing was delayed after administration of sulpiride (D2-receptor antagonist), quinpirole (D2-receptor agonist), and SCH-23390 (D1-receptor antagonist). By contrast, after administration of SKF-81297 (D1-receptor agonist), interval timing shifted earlier only in male rodents. These data illuminate sex similarities and differences in interval timing. Our results have relevance for rodent models of both cognitive function and brain disease by increasing represenation in behavioral neuroscience.

Helping Women Suffering from Drug Addiction: Needs, Barriers, and Challenges

Statistical data on the use of various psychoactive substances indicate a narrowing of previous differences in substance use between men and women. Data from studies conducted among women suffering from drug addiction are increasingly published, with the authors highlighting the specific needs of this group and the difficulties that women with addiction problems encounter. The current study aimed to identify the barriers and needs of this audience, both when seeking help and during treatment. The method used in the study was secondary content analysis. To identify publications describing the barriers and needs of women suffering from drug addiction, we searched the PubMed database to find publications that met the adopted research objective. We set the data search period to the last ten years to examine the timeliness of the issue under study. The search yielded 199 research reports. Twenty-three articles describing 21 studies were included in the final analysis. The selected publications dealt with the difficulties and challenges faced by women with addiction problems. Barriers to accessing treatment for this group, the needs, and the challenges of helping women suffering from addiction were identified. Results showed that the barriers are mainly stigma but also deficits in the therapeutic offerings for this group. The primary need was identified as the introduction of appropriate drug policies, and the challenges, unfortunately, are the still-reported gender inequalities. To improve the situation of women, regular attention to these issues and the need to include them in national health strategies is essential.

Sex-Related Differences in Voluntary Alcohol Intake and mRNA Coding for Synucleins in the Brain of Adult Rats Prenatally Exposed to Alcohol

Maternal alcohol consumption is one of the strong predictive factors of alcohol use and consequent abuse; however, investigations of sex differences in response to prenatal alcohol exposure (PAE) are limited. Here we compared the effects of PAE throughout gestation on alcohol preference, state anxiety and mRNA expression of presynaptic proteins α-, β- and γ-synucleins in the brain of adult (PND60) male and female Wistar rats. Total RNA was isolated from the hippocampus, midbrain and hypothalamus and mRNA levels were assessed with quantitative RT-PCR. Compared with naïve males, naïve female rats consumed more alcohol in “free choice” paradigm (10% ethanol vs. water). At the same time, PAE produced significant increase in alcohol consumption and preference in males but not in females compared to male and female naïve groups, correspondingly. We found significantly lower α-synuclein mRNA levels in the hippocampus and midbrain of females compared to males and significant decrease in α-synuclein mRNA in these brain areas in PAE males, but not in females compared to the same sex controls. These findings indicate that the impact of PAE on transcriptional regulation of synucleins may be sex-dependent, and in males’ disruption in α-synuclein mRNA expression may contribute to increased vulnerability to alcohol-associated behavior.

Granulocyte colony-stimulating factor (G-CSF) enhances cocaine effects in the nucleus accumbens via a dopamine release-based mechanism

Cocaine use disorder is associated with alterations in immune function including altered expression of multiple peripheral cytokines in humans-several of which correlate with drug use. Individuals suffering from cocaine use disorder show altered immune system responses to drug-associated cues, highlighting the interaction between the brain and immune system as a critical factor in the development and expression of cocaine use disorder. We have previously demonstrated in animal models that cocaine use upregulates the expression of granulocyte colony-stimulating factor (G-CSF)-a pleiotropic cytokine-in the serum and the nucleus accumbens (NAc). G-CSF signaling has been causally linked to behavioral responses to cocaine across multiple behavioral domains. The goal of this study was to define whether increases in G-CSF alter the pharmacodynamic effects of cocaine on the dopamine system and whether this occurs via direct mechanisms within local NAc microcircuits. We find that systemic G-CSF injection increases cocaine effects on dopamine terminals. The enhanced dopamine levels in the presence of cocaine occur through a release-based mechanism, rather than through effects on the dopamine transporter-as uptake rates were unchanged following G-CSF treatment. Critically, this effect could be recapitulated by acute bath application of G-CSF to dopamine terminals, an effect that was occluded by prior G-CSF treatment, suggesting a similar mechanistic basis for direct and systemic exposures. This work highlights the critical interaction between the immune system and psychostimulant effects that can alter drug responses and may play a role in vulnerability to cocaine use disorder.

Gender Perspective in Dual Diagnosis

Little data are available for women diagnosed with a dual diagnosis. However, dual diagnosis in women presents increased stigma, social penalties, and barriers to access to treatment than it does for men. Indeed, it increases the probability of suffering physical or sexual abuse, violent victimization, gender-based violence, unemployment, social exclusion, social-role problems, and physical and psychiatric comorbidities. Thus, a transversal sex and gender-based perspective is required to adequately study and treat dual diagnosis. For this, sex and gender factors should be included in every scientific analysis; professionals should review their own prejudices and stereotypes and train themselves specifically from a gender perspective; administrations should design and provide specific treatment resources for women; and we could all contribute to a structural social transformation that goes beyond gender mandates and norms and reduces the risk of abuse and violence inflicted on women.

A Gender Perspective of Addictive Disorders

Purpose of Review

Substance use disorders (SUD) affect differentially women and men. Although the prevalence has been reported higher in men, those women with addictive disorders present a more vulnerable profile and are less likely to enter treatment than men. The aim of this paper is to present an overview of how sex and gender may influence epidemiology, clinical manifestations, social impact, and the neurobiological basis of these differences of women with SUD, based on human research.

Recent Findings

The differences in prevalence rates between genders are getting narrower; also, women tend to increase the amount of consumption more rapidly than men, showing an accelerated onset of the SUD (telescoping effect). In respect to clinical features, the most important differences are related to the risk of experience psychiatric comorbidity, the exposure to intimate partner violence, and the associated high risks in sexual and reproductive health; and those who are mothers and addicted to substances are at risk of losing the custody of children accumulating more adverse life events. Some of these differences can be based on neurobiological differences: pharmacokinetic response to substances, sensitivity to gonadal hormones, differences in neurobiological systems as glutamate, endocannabinoids, and genetic differences.

Summary

Specific research in women who use drugs is very scarce and treatments are not gender-sensitive oriented. For these reasons, it is important to guarantee access to the appropriate treatment of women who use drugs and a need for a gender perspective in the treatment and research of substance use disorders.

Affective Temperament Traits and Age-Predicted Recreational Cannabis Use in Medical Students: A Cross-Sectional Study

The use of cannabis among college students is increasing. Cannabis abuse has been proposed to be associated with personality dimensions. However, there are currently no known studies on the relationship of temperament traits and recreational cannabis use among college students. This is a cross-sectional study that investigated 328 students at a Podiatric Medical College. We evaluated the association between temperament and recreational cannabis use by the students. Temperament was investigated using the Memphis, Pisa, Paris and San Diego Auto- Questionnaire (TEMPS-A (short version)). Additionally, we assessed demographics variables and perceived stress in the context of cannabis use, and analyzed the findings using logistic regression. The prevalence of recreational cannabis use was 8.45%. Recreational cannabis use among these students was highly associated with irritable and cyclothymic temperament traits. There was no association between recreational cannabis use and perceived stress, and demographic variables or other substance use. Furthermore, logistic regression analysis indicated that higher scores in cyclothymic or irritable temperament traits are significant predictors for recreational cannabis use. Our study has identified key temperament traits, with a strong association with recreational use of cannabis of the studied student population. Our findings are useful in designing screening and educational strategies directed towards increasing the wellbeing of medical students.

Prospects for finding the mechanisms of sex differences in addiction with human and model organism genetic analysis

Despite substantial evidence for sex differences in addiction epidemiology, addiction-relevant behaviors and associated neurobiological phenomena, the mechanisms and implications of these differences remain unknown. Genetic analysis in model organism is a potentially powerful and effective means of discovering the mechanisms that underlie sex differences in addiction. Human genetic studies are beginning to show precise risk variants that influence the mechanisms of addiction but typically lack sufficient power or neurobiological mechanistic access, particularly for the discovery of the mechanisms that underlie sex differences. Our thesis in this review is that genetic variation in model organisms are a promising approach that can complement these investigations to show the biological mechanisms that underlie sex differences in addiction.