Environmental Enrichment Preceding Early Adulthood Methylphenidate Treatment Leads to Long Term Increase of Corticosterone and Testosterone in the Rat

Attention-deficit/hyperactivity disorder (ADD/ADHD) has been emerging as a world-wide psychiatric disorder. There appears to be an increasing rate of stimulant drug abuse, specifically methylphenidate (MPH) which is the most common treatment for ADHD, among individuals who do not meet the criteria for ADHD and particularly for cognitive enhancement among university students. However, the long term effects of exposure to MPH are unknown. Thus, in light of a developmental approach in humans, we aimed to test the effects of adolescence exposure to enriched environment (EE) followed by MPH administration during early adulthood, on reactions to stress in adulthood. Specifically, at approximate adolescence [post natal days (PND) 30–60] rats were reared in EE and were treated with MPH during early adulthood (PND 60–90). Adult (PND 90–92) rats were exposed to mild stress and starting at PND 110, the behavioral and endocrine effects of the combined drug and environmental conditions were assessed. Following adolescence EE, long term exposure to MPH led to decreased locomotor activity and increased sucrose preference. EE had a beneficial effect on PPI (attentive abilities), which was impaired by long term exposure to MPH. Finally, the interaction between EE and, exposure to MPH led to long-term elevated corticosterone and testosterone levels. In view of the marked increase in MPH consumption over the past decade, vigilance is crucial in order to prevent potential drug abuse and its long term detrimental consequences

Persistent Heightened Cortisol Awakening Response and Adolescent Internalizing Symptoms: A 3-year Longitudinal Community Study

An atypical Cortisol Awakening Response (CAR) has been related to adult anxiety and depression, but little is known about the association between long-term atypical CAR and adolescent anxiety and depression. This study aimed to longitudinally identify subgroups of adolescents with distinct levels of CAR (i.e., adolescents with and without persistent atypical CAR) and to examine their development of anxiety and depressive symptoms over 3 successive years. A community sample of 184 Dutch adolescents (M age∈=∈14.99 at T1, 57 % boys) completed annual salivary cortisol assessments at home at time of awakening, and 30 and 60 min post-awakening (i.e., CAR) for 3 successive years. Adolescents also reported annually on their anxiety and depressive disorder symptoms. Latent Class Growth Analysis suggested two subgroups of adolescents with respect to CAR: a "low" group with stable low levels of AUCg (Area Under the Curve with respect to the ground) over time and a "high" group with high and increasing levels of AUCg over time. Controlling for sex, the high and low CAR groups significantly differed in depressive symptoms only, but none of the anxiety disorder symptoms. More specifically, adolescents in the high CAR group showed significantly higher mean levels of depressive symptoms over time compared to adolescents in the low CAR group. These results suggest that persistent heightened CAR is a more consistent, yet modest, correlate of adolescent depressive symptoms than anxiety disorder symptoms