Marie-Ève Fortier

Effects of prenatal infection on prepulse inhibition in the rat depend on the nature of the infectious agent and the stage of pregnancy

Maternal infection during pregnancy is a risk factor for some psychiatric illnesses of neurodevelopmental origin such as schizophrenia and autism. In experimental animals, behavioral and neuropathological outcomes relevant to schizophrenia have been observed in offspring of infected dams. However, the type of infectious agent used and gestational age at time of administration have varied. The objective of the present study was to compare the effects of prenatal challenge with different immune agents given at different time windows during gestation on behavioral outcomes in offspring. For this, pregnant rats were administered bacterial endotoxin (lipopolysaccharide, LPS), the viral mimic polyinosinic: polycytidylic acid (poly I:C), or turpentine, an inducer of local inflammation, at doses known to produce fever, at three different stages in pregnancy: embryonic day (E)10-11, E15-16 and E18-19. Prepulse inhibition of acoustic startle (PPI) was later measured in male adult offspring. PPI was significantly decreased in offspring after prenatal LPS treatment at E15-16 and E18-19. Intramuscular injection of pregnant dams with turpentine at E15-16 also decreased PPI in adult offspring. Maternal poly I:C administration had no significant effect on PPI in offspring. In contrast to prenatal LPS exposure, acute LPS administration to naive adult males had no effect on PPI. Thus, prenatal exposure both to a systemic immunogen and to local inflammation at brief periods during later pregnancy produced lasting deficits in PPI in rat offspring. These findings support the idea that maternal infection during critical windows of pregnancy could contribute to sensorimotor gating deficits in schizophrenia.

LPHN3 and attention-deficit/hyperactivity disorder: interaction with maternal stress during pregnancy

BACKGROUND Attention-deficit/hyperactivity disorder (ADHD) is a heterogeneous behavioral disorder, complex both in etiology and clinical expression. Both genetic and environmental factors have been implicated, and it has been suggested that gene-environment interactions may play a pivotal role in the disorder. Recently, a significant association was reported between ADHD and LPHN3 (which codes for latrophilin 3), and replicated in independent samples. METHODS We have examined the association between tag single nucleotide polymorphisms (SNPs) in LPHN3 within the region previously implicated in ADHD. Family based association tests (FBAT) were conducted (n = 380 families) with the categorical diagnosis of ADHD, behavioral and cognitive phenotypes related to ADHD, and response to treatment (given a fixed dose of methylphenidate, 0.5 mg/day). Stratified FBAT analyses, based on maternal smoking and stress during pregnancy, was conducted. RESULTS Whereas limited association was observed in the total sample, highly significant interaction between four LPHN3 tag SNPs (rs6551665, rs1947274, rs6858066, rs2345039) and maternal stress during pregnancy was noted. Analysis conducted in the sub-group of mothers exposed to minimal stress during pregnancy showed significant associations with ADHD, behavioral and cognitive dimensions related to ADHD, as well as treatment response. Although extensive association was observed with the candidate SNPs, the findings are partially inconsistent with previously published results with the opposite alleles over-transmitted in these studies. CONCLUSIONS These results provide evidence for the interaction between a genetic and environmental factor independently shown to be associated with ADHD. If confirmed in independent large studies, they may present a step forward in unraveling the complex etiology of ADHD.

Association between obesity‐related gene FTO and ADHD

Attention‐deficit/hyperactivity disorder (ADHD) is an etiologically complex heterogeneous behavioral disorder. Several studies have reported that ADHD subjects are more likely to be overweight/obese and that this comorbidity may be due to shared genetic factors. The objective of this study is to explore the association between ADHD and FTO, a gene strongly associated with obesity in genome‐wide studies.

Refining psychiatric phenotypes for response to treatment: Contribution of LPHN3 in ADHD†‡

Attention deficit/hyperactivity disorder (ADHD) is a heterogeneous disorder characterized by inappropriate levels of attention, hyperactivity, and impulsivity. Although a strong genetic component to the disorder has been established, the molecular genetic underpinnings of this disorder remain elusive. Recently, several studies have reported an association between polymorphisms within the latrophilin 3 gene (LPHN3) and ADHD. Interestingly, the same single‐nucleotide polymorphism conferring susceptibility to ADHD has also been found to predict efficacy of stimulant medication in children. The main objectives of the current article are: (i) To tackle the phenotype heterogeneity issue in ADHD by defining an objective and quantitative measure of response to treatment in a sample of ADHD children based on a hand held automatic device (Actiwatch) and (ii) to use this measure to reproduce for the first time the association between LPHN3 variants and response to methylphenidate (MPH) using a double‐blind, placebo‐controlled crossover experimental design. The results of our study confirm the hypothesis that LPHN3 is associated with response to MPH in ADHD children. Although this will require further validation, our work suggests that the use of an objective measure of response to treatment, such as the change in the childs motor activity measured by Actiwatch, has the potential to uncover genetic association signals that in some conditions might not be obtained using more subjective measures, such as the clinical consensus rating, for example.

Body weight and ADHD: examining the role of self-regulation.

Objective Attention-Deficit/Hyperactivity Disorder (ADHD) is a complex and heterogeneous childhood disorder that often coexists with other psychiatric and somatic disorders. Recently, a link between ADHD and body weight dysregulation has been reported and often interpreted as impaired self-regulation that is shared between the two conditions. The objective of this study is to investigate the relation between body weight/BMI and cognitive, emotional and motor characteristics in children with ADHD. Methods 284 ADHD children were stratified by weight status/BMI according to WHO classification and compared with regard to their neurocognitive characteristics, motivational style, and motor profile as assessed by a comprehensive battery of tests. All comparisons were adjusted for demographic characteristics of relevance including, socioeconomic status (SES). Results Both Obese and overweight ADHD children exhibited significantly lower SES compared to normal weight ADHD children. No significant differences were observed between the three groups with regards to their neurocognitive, emotional and motor profile. Conclusions Our findings provide evidence that differences in weight/BMI are not accounted for by cognitive, motivational and motor profiles. Socio-economic characteristics are strongly associated with overweight and obesity in ADHD children and may inform strategies aimed at promoting healthier weight.

Parental psychopathology in families of children with attention-deficit/hyperactivity disorder and exposed to maternal smoking during pregnancy.

BACKGROUND Both genetic and environmental factors have been implicated in the etiology of attention-deficit/hyperactivity disorder (ADHD). We had previously suggested that exposure to maternal smoking during pregnancy (MSDP) may be a valid basis for delineating a distinct subtype of ADHD, where children exposed to MSDP present with a more severe clinical picture. Here, we examine the psychopathology of parents in this group, to better understand the etiology of ADHD. METHODS Using the Family Interview for Genetic Studies in a sample of 514 families of children with ADHD, we collected data pertaining to lifetime parental psychopathology. Families were stratified based on maternal smoking during the complete gestational period. The frequency of different disorders was compared using the χ2 statistic. RESULTS In the group where mothers smoked during pregnancy, both parents were significantly more likely to have antisocial personality disorder, and problems with alcohol and drug abuse. Mothers had a significantly higher frequency of major depressive disorder (MDD), while fathers showed a trend for both MDD and bipolar disorder. CONCLUSIONS Based on the pattern of psychopathology in parents of children exposed to MSDP, as well as earlier reports of the severe clinical, behavioral, and cognitive phenotype in these children, combined with the large body of epidemiological evidence, we propose that these children present a distinct subtype of ADHD with comorbid conduct disorder. Furthermore, we propose that MSDP may be a proxy measure to help delineate this subtype.

Placebo response and its determinants in children with ADHD across multiple observers and settings: A randomized clinical trial

This study aims to quantify placebo response (PR) in children with attention deficit hyperactivity disorder (ADHD) as assessed by parents and teachers and to explore some of its determinants.

Apgar Scores Are Associated with Attention-Deficit/Hyperactivity Disorder Symptom Severity

Objective: Adverse events during pregnancy and delivery have been linked to attention-deficit/hyperactivity disorder (ADHD). Previous studies have investigated Apgar scores, which assess the physical condition of newborns, in relation to the risk of developing ADHD. We propose to go one step further and examine if Apgar scores are associated with ADHD symptom severity in children already diagnosed with ADHD. Method: ADHD symptoms severity, while off medication, was compared in 2 groups of children with ADHD: those with low (≤6, n = 52) and those with higher (≥7, n = 400) Apgar scores sequentially recruited from the ADHD clinic. Results: Children with low Apgar at 1 minute after birth had more severe symptoms as assessed by the externalizing scale of the Child Behaviour Checklist, the Conners’ Global Index for Parents, and the DSM-IV hyperactivity symptoms count (P = 0.02, <0.01, <0.01, respectively). Conclusion: Low 1-minute Apgar scores are associated with a significant increase in ADHD symptom severity. These findings underline the importance of appropriate pregnancy and perinatal care.

Dissecting genetic cross-talk between ADHD and other neurodevelopmental disorders: Evidence from behavioural, pharmacological and brain imaging investigations

Several epidemiological and genetic studies have provided evidence of an overlap between neurodevelopmental disorders. However, the details of the etiological pathways remain to be elucidated. In this study, we garnered the findings of previous GWAS, conducted with schizophrenia and bipolar disorder. We conducted an exploratory study to examine the association between these SNPs and quantitative clinical/ behavioural/ cognitive/ structural brain parameters, as well as response to treatment with a fixed dose of methylphenidate, in a relatively large sample of children with ADHD. Family-based association tests were conducted with nine tag SNPs with 602 nuclear families. In addition, structural magnetic resonance imaging (sMRI) was conducted in a subset of children with ADHD (n = 76). Of the 9 tag SNPs examined, rs1602565 showed a significant association with ADHD, several dimensional measures and response to treatment. An association was also observed between rs1006737 (CACNA1C) and performance IQ. In addition, significant reductions in cortical thickness measurements were observed with the risk allele in rs1006737. These results provide preliminary evidence for putative shared genetic vulnerability between childhood ADHD and other neurodevelopmental disorders.