Assessment of Susceptibility Risk Factors for ADHD in Imaging Genetic Studies.

OBJECTIVE: ADHD consists of a count of symptoms that often presents heterogeneity due to overdispersion and excess of zeros. Statistical inference is usually based on a dichotomous outcome that is underpowered. The main goal of this study was to determine a suited probability distribution to analyze ADHD symptoms in Imaging Genetic studies. METHOD: We used two independent population samples of children to evaluate the consistency of the standard probability distributions based on count data for describing ADHD symptoms. RESULTS: We showed that the zero-inflated negative binomial (ZINB) distribution provided the best power for modeling ADHD symptoms. ZINB reveals a genetic variant, rs273342 (Microtubule-Associated Protein [MAPRE2]), associated with ADHD ( p value = 2.73E-05). This variant was also associated with perivascular volumes (Virchow-Robin spaces; p values < 1E-03). No associations were found when using dichotomous definition. CONCLUSION: We suggest that an appropriate modeling of ADHD symptoms increases statistical power to establish significant risk factors.

[Is there vitamin D deficiency in children in a sunny Mediterranean city?]. / ¿Existe déficit de vitamina D en los niños de una ciudad soleada del Mediterráneo?

INTRODUCTION: Despite the increasing interest in vitamin D functions, new cases of deficiency have been reported in sunny regions where optimal levels are expected. The aim of this study was to analyze 25-hydroxivitamin D levels in children younger than 2 years admitted for acute mild diseases in a tertiary hospital in Valencia and its relationship with factors that can be associated with its deficiency. METHODS: This one year prospective and observational study was conducted on 169 children admitted for acute mild diseases. 25-hydroxivitamin D levels were analyzed. A standardized physical examination and structured interviews to the parents were performed. Children were classified into two groups, according to 25-hydroxivitamin D levels (cut-off 30 ng/mL). RESULTS: A total of 169 children were included, with a median age of 9 months, being more prevalent Caucasians (75.7%) and youger than one year old (79.3%). Almost one quarter (24.3%) of the children had 25-hydroxivitamin D levels <30 ng/mL, more frequently in winter/spring, and in children with higher skin phototypes (P<.01). Levels >30 ng/mL were associated with vitamin D prophylaxis during the first year, in children of a Caucasian mother, and those who did not wear a hijab. No statistical differences were found in diet characteristics (P=.65). Prophylaxis was given to 47% of the breastfed children younger than one year. CONCLUSIONS: In Valencia, Spain, 25-hydroxivitamin D levels lower than 30 ng/mL were found in a quarter of the children younger than two years. Our results emphasize the importance of vitamin D prophylaxis during the first year of life, even in sunny Mediterranean regions.

Development of a middle fossa arachnoid cyst. A theory on its pathogenesis.

The progression of congenital arachnoid cysts has seldom been documented. We report the case of a child who was diagnosed with arrested hydrocephalus at the age of 13 months. Neuroimaging studies performed when the girl was 22 months old showed the appearance of an arachnoid cyst in the right middle fossa, while the previously enlarged ventricles seemed to have decreased in size. To the best of our knowledge, the paradoxical expansion of an arachnoid pouch following a reduction in the size of the ventricular system has not previously been documented. We advance the hypothesis that the development of some cases of arachnoid cyst might be pathogenically related to impaired CSF dynamics associated with pre-existing hydrocephalus. We also briefly review the pertinent literature on the formation and evolution of congenital cerebral arachnoid cysts.