Exposure to tobacco smoke among Canadian nonsmokers based on questionnaire and biomonitoring data.

BACKGROUND: Secondhand smoke exposure (SHSe) is associated with numerous adverse health effects and is a major burden for those who do not smoke. SHSe has been primarily characterized via questionnaire, but exposure levels can also be estimated using a specific biomarker, such as cotinine (COT). DATA AND METHODS: Urinary COT measurements and questionnaire data from three cycles (2007 to 2013) of the Canadian Health Measures Survey were combined and analyzed as indicators of regular SHSe for nonsmokers aged 6 to 79 years. Exposure extent was examined by demographic and socioeconomic variable, dwelling type, and exposure location. RESULTS: Among Canadian nonsmokers, 22% reported having been regularly exposed to smoke; of those, 26% had detectable COT. The range of SHSe significantly differed by age group and exposure location. While the most frequently reported location category was "outside their home" (16%), the most important contributor to elevated COT was exposure "at home". The creatinine-adjusted COT geometric mean (C_COT-GM) for the nonsmokers aged 6 to 79 reporting regular home exposure was 3.7 µg/g, but the C_COT-GM was almost three times higher for those living in an apartment than for those in a single-detached home. Some discrepancy appeared between self-reported SHSe and detectable COT estimates for the assessed subpopulations. DISCUSSION: Surveillance by questionnaire and biomonitoring both have their own advantages and are fundamental in identifying the subpopulations most susceptible to SHSe. Using a biomarker provides a quantitative estimate of relative exposure that can be compared over time and with other studies, and this is of particular interest for effective public health interventions.

Neurofeedback training induces changes in white and gray matter.

The main objective of this structural magnetic resonance imaging (MRI) study was to investigate, using diffusion tensor imaging, whether a neurofeedback training (NFT) protocol designed to improve sustained attention might induce structural changes in white matter (WM) pathways, purportedly implicated in this cognitive ability. Another goal was to examine whether gray matter (GM) volume (GMV) might be altered following NFT in frontal and parietal cortical areas connected by these WM fiber pathways. Healthy university students were randomly assigned to an experimental group (EXP), a sham group, or a control group. Participants in the EXP group were trained to enhance the amplitude of their ß1 waves at F4 and P4. Measures of attentional performance and MRI data were acquired one week before (Time 1) and one week after (Time 2) NFT. Higher scores on visual and auditory sustained attention were noted in the EXP group at Time 2 (relative to Time 1). As for structural MRI data, increased fractional anisotropy was measured in WM pathways implicated in sustained attention, and GMV increases were detected in cerebral structures involved in this type of attention. After 50 years of research in the field of neurofeedback, our study constitutes the first empirical demonstration that NFT can lead to microstructural changes in white and gray matter.

Comparing United States and Canadian population exposures from National Biomonitoring Surveys: bisphenol A intake as a case study.

The Centers for Disease Control and Prevention provides biomonitoring data in the United States as part of the National Health and Nutrition Examination Survey (NHANES). Recently, Statistics Canada initiated a similar survey - the Canadian Health Measures Survey (CHMS). Comparison of US and Canadian biomonitoring data can generate hypotheses regarding human exposures from environmental media and consumer products. To ensure that such comparisons are scientifically meaningful, it is essential to first evaluate aspects of the surveys' methods that can impact comparability of data. We examined CHMS and NHANES methodologies, using bisphenol A (BPA) as a case study, to evaluate whether survey differences exist that would hinder our ability to compare chemical concentrations between countries. We explored methods associated with participant selection, urine sampling, and analytical methods. BPA intakes were also estimated to address body weight differences between countries. Differences in survey methods were identified but are unlikely to have substantial impacts on inter-survey comparisons of BPA intakes. BPA intakes for both countries are below health-based guidance values set by the US, Canada and the European Food Safety Authority. We recommend that before comparing biomonitoring data between surveys, a thorough review of methodologic aspects that might impact biomonitoring results be conducted.

Iron sufficiency of Canadians.

BACKGROUND: Iron deficiency is the most common nutritional deficiency in the world, but little is known about the iron status of people in Canada, where the last estimates are from 1970-1972. DATA AND METHODS: The data are from cycle 2 (2009 to 2011) of the Canadian Health Measures Survey, which collected blood samples from a nationally representative sample of Canadians aged 3 to 79. Descriptive statistics (percentages, arithmetic means, geometric means) were used to estimate hemoglobin and serum ferritin concentrations, and other markers of iron status. Analyses were performed by age/sex group, household income, self-perceived health, diet, and use of iron supplements. World Health Organization reference values (2001) were used to estimate the prevalence of iron sufficiency and anemia. RESULTS: The overall prevalence of anemia was low in the 2009-to-2011 period--97% of Canadians had sufficient hemoglobin levels. Generally, hemoglobin concentration increased compared with 1970-1972; however, at ages 65 to 79, rates of anemia were higher than in 1970-1972. Depleted iron stores were found in 13% of females aged 12 to 19 and 9% of females aged 20 to 49. Lower household income was associated with a lower prevalence of hemoglobin sufficiency, but was not related to lower serum ferritin sufficiency. Self-perceived health and diet were not significantly associated with hemoglobin and serum ferritin levels. INTERPRETATION: The lack of a relationship between iron status and diet may be attributable to the use of questions about food consumption frequency that were not specifically designed to estimate dietary iron intake. Factors other than iron intake might have contributed to the increase in the prevalence of anemia among seniors.

Lead and bisphenol A concentrations in the Canadian population.

BACKGROUND: Lead is a known toxicant that occurs naturally in the environment. Bisphenol A (BPA) is an industrial chemical used primarily in polycarbonate plastic and epoxy resins. It has been 30 years since lead exposure was measured at a national level, and it is the first time for a national assessment of BPA exposure. DATA AND METHODS: Data are from the 2007-2009 Canadian Health Measure Survey. Lead in whole blood (PbB) and urinary BPA were measured in 5319 and 5476 respondents aged 6 to 79, respectively. Geometric means (GMs) are presented by age group and sex for PbB (pg/dL), volume-based BPA (microg/L), and creatinine-standardized BPA (microg/g creatinine). Adjusted least squares geometric means (LSGMs) for PbB and BPA are presented by selected covariates. RESULTS: PbB was detected in 100% of the population, with a GM concentration of 1.34 microg/dL. Adults aged 60 to 79 and males had significantly higher GM PbB concentrations. Lower household income, being born outside Canada, living in a dwelling at least 50 years old, current or former smoking, and drinking alcohol at least once a week were associated with higher PbB concentrations. Urinary BPA was detected in 91% of the population, with a GM concentration of 1.16 microg/L (1.40 microg/g creatinine). Children aged 6 to 11 had significantly higher GM creatinine-standardized BPA concentrations than did other age groups. INTERPRETATION: Although PbB concentrations have declined dramatically since the 1970s, socio-demographic characteristics, the age of dwellings, and certain lifestyle behaviours are associated with higher levels. Given the short half-life of orally ingested BPA and the high frequency of detection, the CHMS data suggest continual widespread exposure in the Canadian population.

Increased striatal gray matter densities in patients with schizophrenia and substance use disorder: a voxel-based morphometry study.

We sought to investigate the link between substance abuse and increased striatal gray matter densities (GMD) in schizophrenia, using voxel-based morphometry (VBM). Increased striatal GMD were found in patients with schizophrenia and substance use disorder (n=12), but not schizophrenia only patients (n=11), compared to healthy volunteers (n=15).

Dysfunction in the neural circuitry of emotional self-regulation in major depressive disorder.

An inability to self-regulate negative emotions appears to play a pivotal role in the genesis of major depressive disorder. This inability may be related to a dysfunction of the neural circuitry underlying emotional self-regulation. This functional magnetic resonance imaging study was conducted to test this hypothesis. Depressed individuals and controls were scanned while they attempted to voluntarily down-regulate sad feelings. The degree of difficulty experienced during down-regulation of sadness was higher in depressed individuals. Furthermore, there was greater activation in the right dorsal anterior cingulate cortex, right anterior temporal pole, right amygdala, and right insula in depressed individuals. These results suggest that emotional dysregulation in major depressive disorder is related to a disturbance in the neural circuitry of emotional self-regulation.

Functional magnetic resonance imaging investigation of the effects of neurofeedback training on the neural bases of selective attention and response inhibition in children with attention-deficit/hyperactivity disorder.

Two functional magnetic resonance imaging (fMRI) experiments were undertaken to measure the effect of neurofeedback training (NFT), in AD/HD children, on the neural substrates of selective attention and response inhibition. Twenty unmedicated AD/HD children participated to these experiments. Fifteen children were randomly assigned to the Experimental (EXP) group whereas the other five children were randomly assigned to the Control (CON) group. Only subjects in the EXP group underwent NFT. EXP subjects were trained to enhance the amplitude of the SMR (12-15 Hz) and beta 1 activity (15-18 Hz), and decrease the amplitude of theta activity (4-7 Hz). Subjects from both groups were scanned one week before the beginning of NFT (Time 1) and 1 week after the end of NFT (Time 2), while they performed a "Counting Stroop" task (Experiment 1) and a Go/No-Go task (Experiment 2). At Time 1, in both groups, the Counting Stroop task was associated with significant activation in the left superior parietal lobule. For the Go/No-Go task, no significant activity was detected in the EXP and CON groups. At Time 2, in both groups, the Counting Stroop task was associated with significant activation of the left superior parietal lobule. This time, however, there were significant loci of activation, in the EXP group, in the right ACC, left caudate nucleus, and left substantia nigra. No such activation loci were seen in CON subjects. For the Go/No-Go task, significant loci of activation were noted, in the EXP group, in the right ventrolateral prefrontal cortex, right ACcd, left thalamus, left caudate nucleus, and left substantia nigra. No significant activation of these brain regions was measured in CON subjects. These results suggest that NFT has the capacity to functionally normalize the brain systems mediating selective attention and response inhibition in AD/HD children.

Effect of neurofeedback training on the neural substrates of selective attention in children with attention-deficit/hyperactivity disorder: a functional magnetic resonance imaging study.

Attention Deficit Hyperactivity Disorder (AD/HD) is a neurodevelopmental disorder mainly characterized by impairments in cognitive functions. Functional neuroimaging studies carried out in individuals with AD/HD have shown abnormal functioning of the anterior cingulate cortex (ACC) during tasks involving selective attention. In other respects, there is mounting evidence that neurofeedback training (NFT) can significantly improve cognitive functioning in AD/HD children. In this context, the present functional magnetic resonance imaging (fMRI) study was conducted to measure the effect of NFT on the neural substrates of selective attention in children with AD/HD. Twenty AD/HD children--not taking any psychostimulant and without co-morbidity-participated to the study. Fifteen children were randomly assigned to the Experimental (EXP) group (NFT), whereas the other five children were assigned to the Control (CON) group (no NFT). Subjects from both groups were scanned 1 week before the beginning of the NFT (Time 1) and 1 week after the end of this training (Time 2), while they performed a Counting Stroop task. At Time 1, for both groups, the Counting Stroop task was associated with significant loci of activation in the left superior parietal lobule. No activation was noted in the ACC. At Time 2, for both groups, the Counting Stroop task was still associated with significant activation of the left superior parietal lobule. This time, however, for the EXP group only there was a significant activation of the right ACC. These results suggest that in AD/HD children, NFT has the capacity to normalize the functioning of the ACC, the key neural substrate of selective attention.

The impact of individual differences on the neural circuitry underlying sadness.

Several functional neuroimaging studies have been carried out in healthy subjects to investigate the neural correlates of sadness. Importantly, there is little consistency among the results of these studies. Hypothesizing that individual differences may account for the discrepancies among these investigations, we conducted two functional magnetic resonance imaging (fMRI) studies to identify the neural circuitry underlying this basic emotion. In these two methodologically identical studies, two different groups (n = 10 for each study) of healthy female subjects were scanned while they were experiencing a transient state of sadness induced by viewing sad film excerpts. In the first of these studies, sadness was correlated with significant loci of activation in the anterior temporal pole and insula (P < 0.05, corrected). In the second study, however, sadness was correlated with significant activation in the orbitofrontal and medial prefrontal cortices (P < 0.05, corrected). In addition, individual statistical parametric maps revealed a marked degree of interindividual variability in both Study 1 and Study 2. These results strongly support the view that individual differences may be responsible for the inconsistencies found in the literature regarding the neural substrates of sadness and of other basic emotions. These findings also suggest that individual data should be reported in addition to group data, because they provide useful information about the variability present in the subjects investigated and, thus, about the typicality and generalizability of the results.

Separate neural circuits for primary emotions? Brain activity during self-induced sadness and happiness in professional actors.

The question of whether distinct or similar neural substrates underlie primary emotions has not been resolved yet. To address this issue, we used fMRI to scan professional actors during self-induced states of sadness and happiness. Results demonstrated that, relative to an emotionally Neutral state, both the Sad and the Happy states were associated with significant loci of activation, bilaterally, in the orbitofrontal cortex, and in the left medial prefrontal cortex, left ventrolateral prefrontal cortex, left anterior temporal pole, and right pons. These loci of activation were localized distinctly within these regions, that is, in different sub-regions. These results suggest that sadness and happiness may be associated with similar brain regions but distinct sub-regions and neural circuits.

Neural circuitry underlying voluntary suppression of sadness.

BACKGROUND: The ability to voluntarily self-regulate negative emotion is essential to a healthy psyche. Indeed, a chronic incapacity to suppress negative emotion might be a key factor in the genesis of depression and anxiety. Regarding the neural underpinnings of emotional self-regulation, a recent functional neuroimaging study carried out by our group has revealed that the dorsolateral prefrontal cortex (DLPFC) and anterior cingulate cortex are involved in voluntary suppression of sexual arousal. As few things are known, still, with respect to the neural substrate underlying volitional self-regulation of basic emotions, here we used functional magnetic resonance imaging to identify the neural circuitry associated with the voluntary suppression of sadness. METHODS: Twenty healthy female subjects were scanned during a Sad condition and a Suppression condition. In the Sad condition, subjects were instructed to react normally to sad film excerpts whereas, in the Suppression condition, they were asked to voluntarily suppress any emotional reaction in response to comparable stimuli. RESULTS: Transient sadness was associated with significant loci of activation in the anterior temporal pole and the midbrain, bilaterally, as well as in the left amygdala, left insula, and right ventrolateral prefrontal cortex (VLPFC) (Brodmann area [BA] 47). Correlational analyses carried out between self-report ratings of sadness and regional blood oxygen level dependent (BOLD) signal changes revealed the existence of positive correlations in the right VLPFC (BA 47), bilaterally, as well as in the left insula and the affective division of the left anterior cingulate gyrus (BA 24/32). In the Suppression condition, significant loci of activation were noted in the right DLPFC (BA 9) and the right orbitofrontal cortex (OFC) (BA 11), and positive correlations were found between the self-report ratings of sadness and BOLD signal changes in the right OFC (BA 11) and right DLPFC (BA 9). CONCLUSIONS: These results confirm the key role played by the DLPFC in emotional self-regulation. They also indicate that the right DLPFC and right OFC are components of a neural circuit implicated in voluntary suppression of sadness.

"Change the mind and you change the brain": effects of cognitive-behavioral therapy on the neural correlates of spider phobia.

Questions pertaining to the neurobiological effects of psychotherapy are now considered among the most topical in psychiatry. With respect to this issue, positron emission tomography (PET) findings indicate that cognitive and behavioral modifications, occurring in a psychotherapeutic context, can lead to regional brain metabolic changes in patients with major depression or obsessive-compulsive disorder. The goal of the present functional magnetic resonance imaging (fMRI) study, which constitutes the first neuroimaging investigation of the effects of cognitive-behavioral therapy (CBT) using an emotional activation paradigm, was to probe the effects of CBT on the neural correlates of spider phobia. In order to do so, fMRI was used in subjects suffering from spider phobia (n = 12) to measure, before and after effective CBT, regional brain activity during the viewing of film excerpts depicting spiders. Normal control subjects were also scanned (once) while they were exposed to the same film excerpts. Results showed that, in phobic subjects before CBT, the transient state of fear triggered, during the viewing of the phobogenic stimuli, was correlated with significant activation of the right dorsolateral prefrontal cortex (Brodmann area-BA 10), the parahippocampal gyrus, and the visual associative cortical areas, bilaterally. For normal control subjects (n = 13), only the left middle occipital gyrus and the right inferior temporal gyrus were significantly activated. In phobic subjects before CBT, the activation of the dorsolateral prefrontal cortex (BA 10) may reflect the use of metacognitive strategies aimed at self-regulating the fear triggered by the spider film excerpts, whereas the parahippocampal activation might be related to an automatic reactivation of the contextual fear memory that led to the development of avoidance behavior and the maintenance of spider phobia. After successful completion of CBT, no significant activation was found in the dorsolateral prefrontal cortex (BA 10) or the parahippocampal gyrus. These findings suggest that a psychotherapeutic approach, such as CBT, has the potential to modify the dysfunctional neural circuitry associated with anxiety disorders. They further indicate that the changes made at the mind level, within a psychotherapeutic context, are able to functionally "rewire" the brain.