Reduced prefrontal activation in pediatric patients with obsessive-compulsive disorder during verbal episodic memory encoding.

OBJECTIVE: Patients with obsessive-compulsive disorder (OCD) often present with deficits in episodic memory, and there is evidence that these difficulties may be secondary to executive dysfunction, that is, impaired selection and/or application of memory-encoding strategies (mediation hypothesis). Semantic clustering is an effective strategy to enhance encoding of verbal episodic memory (VEM) when word lists are semantically related. Self-initiated mobilization of this strategy has been associated with increased activity in the prefrontal cortex, particularly the orbitofrontal cortex, a key region in the pathophysiology of OCD. We therefore studied children and adolescents with OCD during uncued semantic clustering strategy application in a VEM functional magnetic resonance imaging (fMRI)-encoding paradigm. METHOD: A total of 25 pediatric patients with OCD (aged 8.1-17.5 years) and 25 healthy controls (HC, aged 8.1-16.9) matched for age, gender, handedness, and IQ were evaluated using a block design VEM paradigm that manipulated semantically related and unrelated words. RESULTS: The semantic clustering strategy score (SCS) predicted VEM performance in HC (p < .001, R(2) = 0.635), but not in patients (p = .099). Children with OCD also presented hypoactivation in the dorsomedial prefrontal cortex (cluster-corrected p < .001). Within-group analysis revealed a negative correlation between Yale-Brown Obsessive Compulsive Scale scores and activation of orbitofrontal cortex in the group with OCD. Finally, a positive correlation between age and SCS was found in HC (p = .001, r = 0.635), but not in patients with OCD (p = .936, r = 0.017). CONCLUSION: Children with OCD presented altered brain activation during the VEM paradigm and absence of expected correlation between SCS and age, and between SCS and total words recalled. These results suggest that different neural mechanisms underlie self-initiated semantic clustering in OCD.

ADHD and mental health status in Brazilian school-age children.

OBJECTIVE: To assess the prevalence of ADHD, mental health status, and risk factors in a sample of Brazilian children. METHOD: Target sample consisted of all children from 5 to 13 years registered in the public elementary school. Children with ADHD were compared with those without ADHD for sociodemographic, risk factors, and Child Behavior Checklist (CBCL) symptom dimensions. Multivariate models estimated determinants of ADHD diagnosis. RESULTS: Of the target sample, consents and complete information were obtained from 1,830 children (91.8%). The prevalence rate of ADHD was 5.1% (95% confidence interval [CI] = [4.2, 6.2]). In contrast to controls, children with ADHD presented higher levels of symptoms in the CBCL dimensions. In multivariate analyses, the diagnosis of ADHD was significantly influenced by maternal educational status (p = .019), income class (p = .012), and prenatal exposure to tobacco (p = .032). CONCLUSION: Prevalence and demographic features of ADHD in Brazil are similar to what has been reported worldwide.