Heritability of Selective Attention and Working Memory in Preschoolers

In this study aspects of selective attention and working memory were tested in a large sample of nearly 6-year old monozygotic and dizygotic twin pairs, using a computerized test battery (Amsterdam Neuropsychological tasks). In the selective attention task the presence of a foil signal (target signal at an irrelevant location) resulted in more false alarms than a non-target signal. In the working memory task an increase in memory load lead to an increase in response times and errors. We analyzed variations in absolute performance parameters (overall speed and accuracy) and relative performance parameters (increase in errors and/or reaction time). The results showed clear familial resemblances on performance. It proved difficult to ascribe these effects to shared genes or to shared environment. An exception was memory search rate, which was clearly heritable.     

Emergency Neurological Life Support: Resuscitation Following Cardiac Arrest

Cardiac arrest is the most common cause of death in North America. An organized bundle of neurocritical care interventions can improve chances of survival and neurological recovery in patients who are successfully resuscitated from cardiac arrest. Therefore, resuscitation following cardiac arrest was chosen as an Emergency Neurological Life Support protocol. Key aspects of successful early post-arrest management include: prevention of secondary brain injury; identification of treatable causes of arrest in need of emergent intervention; and, delayed neurological prognostication. Secondary brain injury can be attenuated through targeted temperature management (TTM), avoidance of hypoxia and hypotension, avoidance of hyperoxia, hyperventilation or hypoventilation, and treatment of seizures. Most patients remaining comatose after resuscitation from cardiac arrest should undergo TTM. Treatable precipitants of arrest that require emergent intervention include, but are not limited to, acute coronary syndrome, intracranial hemorrhage, pulmonary embolism and major trauma. Accurate neurological prognostication is generally not appropriate for several days after cardiac arrest, so early aggressive care should never be limited based on perceived poor neurological prognosis.     

The SNAP-25 gene is associated with cognitive ability: evidence from a family-based study in two independent Dutch cohorts

The synaptosomal-associated protein of 25 kDa (SNAP-25) gene plays an integral role in synaptic transmission, and is differentially expressed in the mammalian brain in the neocortex, hippocampus, anterior thalamic nuclei, substantia nigra and cerebellar granular cells. Recent studies have suggested a possible involvement of SNAP-25 in learning and memory, both of which are key components of human intelligence. In addition, the SNAP-25 gene lies in a linkage area implicated previously in human intelligence. In two independent family-based Dutch samples of 391 (mean age 12.4 years) and 276 (mean age 37.3 years) subjects, respectively, we genotyped 12 single-nucleotide polymorphisms (SNPs) in the SNAP-25 gene on 20p12-20p11.2. From all individuals, standardized intelligence measures were available. Using a family-based association test, a strong association was found between three SNPs in the SNAP-25 gene and intelligence, two of which showed association in both independent samples. The strongest, replicated association was found between SNP rs363050 and performance IQ (PIQ), where the A allele was associated with an increase of 2.84 PIQ points (P=0.0002). Variance in this SNP accounts for 3.4% of the phenotypic variance in PIQ.     

Ultrasonographic detection and assessment of preclinical oesophagostomum bifurcum-induced colonic pathology.

In northern Ghana and Togo, Oesophagostomum bifurcum infects an estimated 250,000 people, as determined by cultures of stool samples. The juvenile stages of the helminth develop within colonic wall nodules, causing Dapaong tumor or multinodular disease, at the rate of 1 case per week at Nalerigu Hospital in Ghana. Our aim was to discover whether suspected colonic-wall pathology is ultrasonographically visible in asymptomatic individuals living in the area where O. bifurcum is endemic. A total of 464 persons from 3 villages, ranging from highly infected to noninfected, were examined with ultrasonography. Anechogenic colonic lesions with posterior wall enhancement were observed in 71 (54.2%) of 131 and 57 (24.5%) of 233 persons from the villages of endemicity, and no lesions were seen in persons from the village outside the area of endemicity. We describe the lesions noted in this study as nodules caused by O. bifurcum, on the basis of their association at a population level with prevalence of larvae in stools, their expected ultrasonographic appearance and distribution (on the basis of our surgical experience with oesophagostomiasis), and the lack of a convincing differential diagnosis.     

Exploring the functional role of the CHRM2 gene in human cognition: results from a dense genotyping and brain expression study

Background  

The CHRM2 gene, located on the long arm of chromosome 7 (7q31-35), is involved in neuronal excitability, synaptic plasticity and feedback regulation of acetylcholine release, and has been implicated in higher cognitive processing. The aim of this study is the identification of functional (non)coding variants underlying cognitive phenotypic variation.