Timing and delay discounting in attention-deficit/hyperactivity disorder: A translational approach.

Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder that often presents with abnormal time perception and increased impulsive choice behavior. The spontaneously hypertensive rat (SHR) is the most widely used preclinical model of the ADHD-Combined and ADHD-Hyperactive/Impulsive subtypes of the disorder. However, when testing the spontaneously hypertensive rat from Charles River (SHR/NCrl) on timing and impulsive choice tasks, the appropriate control strain is not clear, and it is possible that one of the possible control strains, the Wistar Kyoto from Charles River (WKY/NCrl), is an appropriate model for ADHD-Predominately Inattentive. Our goals were to test the SHR/NCrl, WKY/NCrl, and Wistar (WI; the progenitor strain for the SHR/NCrl and WKY/NCrl) strains on time perception and impulsive choice tasks to assess the validity of SHR/NCrl and WKY/NCrl as models of ADHD, and the validity of the WI strain as a control. We also sought to assess impulsive choice behavior in humans diagnosed with the three subtypes of ADHD and compare them with our findings from the preclinical models. We found SHR/NCrl rats timed faster and were more impulsive than WKY/NCrl and WI rats, and human participants diagnosed with ADHD were more impulsive compared to controls, but there were no differences between the three ADHD subtypes.

Personality as a mediator of autistic traits and internalizing symptoms in two community samples.

BACKGROUND: Autism spectrum disorder (ASD) is characterized by deficits in social functioning and is comorbid with internalizing disorders and symptoms. While personality is associated with these symptoms and social functioning in non-ASD samples, its role mediating the relationship between ASD traits and internalizing symptoms is not clear. METHODS: We studied the mediating effect of personality on the correlations between ASD traits and internalizing symptoms (i.e., depression, anxiety, stress) in two samples. Additionally, we explored the moderating effect of gender. Analyses were applied to a small (Study 1; N = 101) undergraduate sample. A broader sample recruited via an online crowdsourcing platform (Study 2; N = 371) was used to validate the results. RESULTS: Study 1's mediation analyses revealed that neuroticism was the only significant mediator. Study 2 replicated these results by finding extraversion to be an additional mediator for anxiety and extraversion, openness, and agreeableness as additional mediators for stress. Moderation analyses revealed that gender was never a significant moderator. CONCLUSIONS: These results support the effects of personality on the relationship between autism traits and internalizing symptoms. Future research should explore these effects in clinical samples to better understand the role of personality in symptomatology and the need to address it as part of intervention.

Autistic Traits Moderate Reappraisal Success for Depression and Anxiety Symptoms.

Cognitive reappraisal is associated with reduced emotional distress; however, little is known about the nature of this relationship in autism. This study tested whether autistic traits moderate reappraisal success (i.e., the negative correlation between reappraisal use and emotional symptom severity). Emotional symptoms were assessed using measures of depression, anxiety, and stress. It was hypothesized that more severe autistic traits would be associated with weaker reappraisal success across all scales. Data were collected from 377 adults using an on-line survey. Structural equation models found moderation effects for depression and anxiety, but not stress. Contrary to hypotheses, more severe autistic traits were associated with stronger reappraisal success. These preliminary results support including reappraisal in emotion regulation treatments for individuals with autistic traits.

Interventions aimed at changing impulsive choice in rats: Effects of immediate and relatively long delay to reward training.

A relatively strong preference for smaller-sooner rewards (SSR) over larger-later rewards (LLR) is associated with a host of maladaptive behavioral patterns. As such, the clinical implications for increasing preference for LLR are profound. There is a growing body of literature that suggests extended exposure to delayed reward may increase preference for LLR in rats. However, questions remain about the underlying mechanism driving this effect and the extent to which extended exposure to immediate rewards may decrease LLR choice. In Experiment 1, we tested effects of a differential-reinforcement-of-low-rates schedule (DRL) to increase LLR choice using a pretest/posttest design with Wistar rats as subjects. We compared this group to a group of rats exposed to a differential-reinforcement-of-high-rates schedule (DRH). The DRH intervention has never been employed in this research context, but explicitly programs an immediate response-reinforcement requirement. In Experiment 2, we tested effects of an intervention with a delay longer than those used in the delay discounting pretest and posttest. No previous research has tested effects of an intervention delay this long, relative to the delay discounting task. We compared this group to a group exposed to a delay that was part of the delay discounting pretest and posttest and to a group exposed to a traditional no-delay, fixed-ratio (FR) 2 control intervention. In both experiments, we found that exposure to delayed rewards in the intervention phase significantly increased LLR choice relative to pretest performance. These findings replicate and extend a growing body of literature showing that delay exposure increases preference for LLR. We also found significant decreases in LLR choice from pretest to posttest in the DRH and no-delay intervention groups in Experiments 1 and 2, respectively. This is the first report of such an effect and has implications for understanding and interpreting effects of delay exposure training in past and future research. Our results also suggested no relationship between improved temporal tracking of reward and increases in LLR choice as a result of delay exposure training.