Addictions are often characterized as forms of impulsive behavior. That said, it is often noted that impulsivity is a multidimensional construct, spanning several psychological domains. This review describes the relationship between varieties of impulsivity and addiction-related behaviors, the nature of the causal relationship between the two and the underlying neurobiological mechanisms that promote impulsive behaviors. We conclude that the available data strongly supports the notion that impulsivity is both a risk factor for, and a consequence of, drug and alcohol consumption. While the evidence indicating that subtypes of impulsive behavior are uniquely informative – either biologically or with respect to their relationships to addictions – is convincing, multiple lines of study link “distinct” subtypes of impulsivity to low dopamine D2 receptor function and perturbed serotonergic transmission, revealing shared mechanisms between the subtypes. Therefore, a common biological framework involving monoaminergic transmitters in key frontostriatal circuits may link multiple forms of impulsivity to drug self-administration and addiction-related behaviors. Further dissection of these relationships is needed before the next phase of genetic and genomic discovery will be able to reveal the biological sources of the vulnerability for addiction indexed by impulsivity.

BackgroundGiven the frequency of natural hazards in Haiti, disaster risk reduction is crucial. However, evidence suggests that many people exposed to prior disasters do not engage in disaster preparedness, even when they receive training and have adequate resources. This may be partially explained by a link between mental health symptoms and preparedness; however, these components are typically not integrated in intervention.MethodsThe current study assesses effectiveness of an integrated mental health and disaster preparedness intervention. This group-based model was tested in three earthquake-exposed and flood-prone communities (N = 480), across three time points, using a randomized controlled trial design. The 3-day community-based intervention was culturally-adapted, facilitated by trained Haitian lay mental health workers, and focused on enhancing disaster preparedness, reducing mental health symptoms, and fostering community cohesion.ResultsConsistent with hypotheses, the intervention increased disaster preparedness, reduced symptoms associated with depression, post-traumatic stress disorder, anxiety, and functional impairment, and increased peer-based help-giving and help-seeking. Mediation models indicated support for the underlying theoretical model, such that the effect of the intervention on preparedness was mediated by mental health, and that effects on mental health were likewise mediated by preparedness.ConclusionsThe community-based mental health-integrated disaster preparedness intervention is effective in improving mental health and preparedness among community members in Haiti vulnerable to natural hazards. This brief intervention has the potential to be scaled up for use with other communities vulnerable to earthquakes, seasonal flooding, and other natural hazards.

BackgroundOn 25th April 2015, Nepal experienced a 7.8 magnitude earthquake, followed by countless aftershocks. Nearly 9000 people were killed and over 600,000 homes destroyed. Given the high frequency of earthquake and other natural hazards in Nepal, disaster preparedness is crucial. However, evidence suggests that some people exposed to prior disasters do not engage in risk reduction, even when they receive training and have adequate resources. Mental health symptoms, including those associated with prior disaster exposure, may influence engagement in preparedness. Perceived preparedness for future disasters may in turn influence mental health. Social cohesion may influence both mental health and preparedness.MethodsWe developed and tested a hybrid mental health and disaster preparedness intervention in two earthquake-affected communities in Nepal (N = 240), about 2.5 months after the April 25th, 2015 earthquake. The 3-day intervention was culturally adapted, facilitated by trained Nepalese clinicians and focused on enhancing disaster preparedness, mental health, and community cohesion. Communities were selected based on earthquake impacts and matched on demographic variables. The intervention was administered initially to one community, followed by the other receiving the intervention shortly thereafter. Survey data was collected across three time points. Focus groups were also conducted to examine intervention impact.ResultsAt pre-intervention baseline, greater depression symptoms and lower social cohesion were associated with less disaster preparedness. Depression and PTSD were associated with lower social cohesion. Participation in the intervention increased disaster preparedness, decreased depression- and PTSD-related symptoms, and increased social cohesion. Mediation models indicated that the effect of intervention on depression was partially explained by preparedness. The effect of the intervention on disaster preparedness was partially explained by social cohesion, and the effect of intervention on depression and on PTSD was also partially explained by social cohesion. Data from focus groups illuminate participant perspectives on components of the intervention associated with preparedness, mental health and social cohesion.ConclusionsThis mental health integrated disaster preparedness intervention is effective in enhancing resilience among earthquake-affected communities in Nepal. This brief, cost-effective group intervention has the potential to be scaled up for use with other communities vulnerable to earthquakes and other natural hazards.Trial registrationClinical Trials Registry-India, National Institute of Medical Statistics. Registration number: CTRI/2018/02/011688. http://ctri.nic.in/Clinicaltrials/login.php Retrospectively registered February 5th, 2018. First participant enrolled July 2015.

Neuroimaging studies in animal models and human subjects have each revealed that relatively low striatal dopamine D2-like receptor binding potential is associated with poor impulse control and with vulnerability for addiction-related behaviors. These studies cannot, however, disambiguate the roles for various pools of D2 receptors found in the striatum (e.g., those expressed on medium spiny striato-pallidal neurons vs on dopamine-releasing nerve terminals) in these behavioral outcomes. To clarify the role of the latter pool, namely, D2 autoreceptors, we studied mice carrying a conditional DRD2 gene, with or without Cre-recombinase expressed under the transcriptional control of the dopamine transporter gene locus (autoDrd2-KO, n = 19 and controls, n = 21). These mice were tested for locomotor response to cocaine, and spatial reversal learning was assessed in operant conditioning chambers. As predicted, compared to control mice, autoDrd2-KO animals demonstrated heightened sensitivity to the locomotor stimulating effect of cocaine (10 mg/kg, i.p.), confirming previous research using a similar genetic model. In the spatial reversal learning task, autoDrd2-KO mice were slower to reach a learning criterion and had difficulty sustaining a prolonged nose poke response, measurements conceptually related to impaired response inhibition. Rate of learning of the initial discrimination and latencies to collect rewards, to initiate trials and to produce a response were unaffected by genetic deletion of D2 autoreceptors, discarding possible motor and motivational factors. Together, these findings confirm the role of D2 autoreceptors in reversal learning and suggest a broader involvement in behavioral inhibition mechanisms.