Previous neuroimaging studies of working memory (WM) in schizophrenia have generated conflicting findings of hypo-and hyper-frontality, discrepancies potentially driven by differences in task difficulty and/or performance. This study proposes and tests a new model of the performanceactivation relationship in schizophrenia by combining changes by load with overall individual differences in performance. Fourteen patients with recent-onset schizophrenia and eighteen controls underwent functional magnetic resonance imaging while performing a parametric verbal WM task. Group level differences followed a linear "cross-over" pattern, such that in controls, activation in the dorsolateral prefrontal cortex (DLPFC) increased as performance decreased, while patients showed the opposite. Overall, low performing patients were hypoactive and high performing patients hyperactive relative to controls. However, patients and controls showed similar functions of activation by load in which activation rises with task difficulty but levels off or slightly decreases at higher loads. Moreover, across all loads and at their own WM capacity, higher performing patients showed greater DLPFC activation than controls, while lower performing patients activated least. This study establishes a novel framework for predicting the relationship between functional activation and WM performance by combining changes of activation by WM load occurring within each subject with the overall differences in activation associated with general WM performance. Essentially, increasing task difficulty correlates asymptotically with increasing activation in all subjects, but depending on their behavioral performance, patients show overall hyper-versus hypofrontality, a pattern potentially derived from individual differences in underlying cellular changes that may relate to levels of functional disability.
In 2012, the American Heart Association and the American Academy of Paediatrics released a scientific statement with guidelines for the evaluation and management of the neurodevelopmental needs of children with CHD. Decades of outcome research now highlight a range of cognitive, learning, motor, and psychosocial vulnerabilities affecting individuals with CHD across the lifespan. The number of institutions with Cardiac Neurodevelopmental Follow-Up Programmes and services for CHD is growing worldwide. This manuscript provides an expanded set of neurodevelopmental evaluation strategies and considerations for professionals working with school-age children with CHD. Recommendations begin with the referral process and access to the evaluation, the importance of considering medical risk factors (e.g., genetic disorders, neuroimaging), and the initial clinical interview with the family. The neurodevelopmental evaluation should take into account both family and patient factors, including the child/family’s primary language, country of origin, and other cultural factors, as well as critical stages in development that place the child at higher risk. Domains of assessment are reviewed with emphasis on target areas in need of evaluation based on current outcome research with CHD. Finally, current recommendations are made for assessment batteries using a brief core battery and an extended comprehensive clinical battery. Consistent use of a recommended assessment battery will increase opportunities for research collaborations, and ultimately help improve the quality of care for families and children with CHD.
Objective Executive Function, a set of cognitive skills important to social and academic outcomes, is a specific area of cognitive weakness in children with congenital heart disease (CHD). We evaluated the prevalence and profile of executive dysfunction in a heterogeneous sample of school aged children with CHD, examined whether children with executive dysfunction are receiving school services and support, and identified risk factors for executive dysfunction at school age. Design 91 school aged patients completed questionnaires, including the Behavior Rating Inventory of Executive Function (BRIEF) and a medical history questionnaire. An age and gender matched control sample was drawn from a normativedatabase. Results CHD patients had a higher rate of parent reported executive dysfunction (OR=4.37, p<0.0001), especially for working memory (OR=8.22, p<0.0001) and flexibility (OR=8.05, p<0.0001). Those with executive dysfunction were not more likely to be receiving school services (p>0.05). Gender, premature birth (≤37 weeks), and CHD with aortic obstruction were predictive of executive dysfunction, especially for behavior regulation skills. Conclusions School aged children with CHD have an increased prevalence of executive dysfunction, especially problems with working memory and flexibility, and are underserved by the school system. The increased risk for executive dysfunction in those with CHD and prematurity or CHD with aortic obstruction suggests an etiology of delayed brain development in the fetal and neonatal periods, while male gender may increase susceptibility to brain injury. This study highlights the need for regular neurodevelopmental follow up in children with CHD, and a need to better understand mechanisms that contribute to adverse neurodevelopmental outcomes.
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