Visceral fat enhances blood pressure reactivity to physical but not mental challenges in male adolescents.

BACKGROUND: Excess visceral fat is a major risk factor for hypertension. Enhanced blood pressure (BP) reactivity and delayed BP recovery from physical and mental challenges predict future hypertension. OBJECTIVES: Determine whether visceral fat is associated with higher BP reactivity and delayed BP recovery from physical and mental challenges during adolescence. METHODS: In a community-based sample of 283 male and 308 female adolescents, we measured visceral fat with magnetic resonance imaging, total body fat with bioimpedance, and beat-by-beat BP with a Finometer at rest and during physical (10-min standing) and mental (2-min math stress) challenges. RESULTS: Males vs. females showed greater BP reactivity and no differences in BP recovery from either type of challenges. Visceral fat was positively associated with BP reactivity to standing up only and in males only (+8.4 ± 3.6 mmHg per 1 log cm(3) of visceral fat, P = 0.008), and this association was independent of total body fat. No association was seen between visceral fat and BP recovery from either type of challenge in either sex. All these associations were independent of age, puberty stage, height and initial BP. CONCLUSIONS: Adolescent males vs. females demonstrate greater BP reactivity but similar BP recovery from physical and mental challenges. Excess visceral fat enhances BP reactivity to physical but not mental challenges in males only.

Opioid receptor mu 1 gene, fat intake and obesity in adolescence.

Dietary preference for fat may increase risk for obesity. It is a complex behavior regulated in part by the amygdala, a brain structure involved in reward processing and food behavior, and modulated by genetic factors. Here, we conducted a genome-wide association study (GWAS) to search for gene loci associated with dietary intake of fat, and we tested whether these loci are also associated with adiposity and amygdala volume. We studied 598 adolescents (12-18 years) recruited from the French-Canadian founder population and genotyped them with 530 011 single-nucleotide polymorphisms. Fat intake was assessed with a 24-hour food recall. Adiposity was examined with anthropometry and bioimpedance. Amygdala volume was measured by magnetic resonance imaging. GWAS identified a locus of fat intake in the µ-opioid receptor gene (OPRM1, rs2281617, P=5.2 × 10(-6)), which encodes a receptor expressed in the brain-reward system and shown previously to modulate fat preference in animals. The minor OPRM1 allele appeared to have a 'protective' effect: it was associated with lower fat intake (by 4%) and lower body-fat mass (by ∼2 kg, P=0.02). Consistent with the possible amygdala-mediated inhibition of fat preference, this allele was additionally associated with higher amygdala volume (by 69 mm(3), P=0.02) and, in the carriers of this allele, amygdala volume correlated inversely with fat intake (P=0.02). Finally, OPRM1 was associated with fat intake in an independent sample of 490 young adults. In summary, OPRM1 may modulate dietary intake of fat and hence risk for obesity, and this effect may be modulated by subtle variations in the amygdala volume.

Visceral fat is associated with lower executive functioning in adolescents.

BACKGROUND: Obesity, a major risk factor for cardiometabolic disease, is associated with lower cognitive performance from childhood to senescence, especially on tasks of executive function. In the cardiovascular domain, fat stored viscerally rather than elsewhere in the body carries particularly high risk. It is unknown whether this is also true in case of obesity-cognition relationships. The aim of this study was to assess the cross-sectional relationship between visceral fat (VF) and cognitive performance in a community sample of healthy adolescents. METHODS: In a community-based sample of 983 adolescents (12-18 years old, 480 males), VF was quantified using magnetic resonance imaging, total body fat was measured using a multifrequency bioimpedance, and cognitive performance was assessed using a battery of cognitive tests measuring executive function and memory. RESULTS: We found that larger volumes of VF were associated with lower performance on six measures of executive function (P=0.0001-0.02). We also found that the association of VF with executive function was moderated by sex for a subset of measures, such that relationship was present mainly in female subjects and not in male subjects (sex-by-VF interaction: P=0.001-0.04). These relationships were independent of the quantity of total body fat and a number of potential confounders, including age, puberty stage and household income. CONCLUSIONS: Our results suggest that the adverse association between obesity and executive function may be attributed to fat stored viscerally and not to fat stored elsewhere in the body. They also suggest that female subjects compared with male subjects may be more sensitive to the potentially detrimental effects of VF on cognition.

Health supervision and anticipatory guidance in adult myotonic dystrophy type 1.

The complexity and variability of disease manifestations in myotonic dystrophy (DM1) pose a challenge for the clinical management of patients. The follow-up of DM1 patients has been described as fragmented, inadequate or even deficient for many patients. Through a systematic review of the medical and social literature and a validation process with a DM1 expert panel, we summarized systemic and social concerns clinically relevant to DM1 and revisited recommendations for treatment. This article summarizes common manifestations of the central nervous system, visual, respiratory, cardiac, gastro-intestinal, genito-urinary, muscular and metabolic impairments. In addition, we emphasized the social features of DM1 such as low education attainment, low employment, poor familial and social environment and poor social participation. While cardiac, respiratory and swallowing problems affect life expectancy, it is often excessive daytime sleepiness, fatigue, gastro-intestinal and cognitive behavioural manifestations that are the most disabling features of the disorder. A more holistic approach in the management of DM1 and a purposeful integrated organization of care involving all members of the patients' environment including family, clinicians, decision-makers and community organizations are needed to move out of the spiral of disease and handicap and move toward optimal citizenship and quality of life.

Clinical and genetic knowledge and attitudes of patients with myotonic dystrophy type 1.

AIMS: The goal was to assess clinical and genetic knowledge and attitudes in patients affected by myotonic dystrophy type 1 (DM1). METHODS: Two hundred patients with molecular confirmation of the diagnosis of DM1 completed a multi-choice questionnaire. DM1 patients' knowledge and views were compared to clinically normal DM1 noncarriers (n = 264) and controls (n = 1,474). RESULTS: Knowledge of the DM1 mode of inheritance was better in noncarriers than in patients (p < 0.001). Noncarriers were more aware than DM1 patients of the common clinical characteristics of DM1 such as limitations in physical activities and problems related to employment, schooling, activities of daily living, parenthood, peer relationships, and personality (p < 0.001). Compared to controls, DM1 patients felt less informed about the availability of clinical genetic services (p < 0.05) and new genetic technologies (p < 0.001). Among patients, logistic regression revealed that each additional year of education (p < 0.05) and each additional 100 CTG repeats (p < 0.01), respectively, increased and decreased the odds of knowing the DM1 mode of inheritance by about 23% and 18% respectively, independently of age, age at onset of symptoms, gender, severity of muscular impairment, and intellectual quotient. CONCLUSIONS: DM1 patients' genetic knowledge is significantly dependent of the level of education and the number of CTG repeats. Healthcare providers should be aware of this situation in order to adjust counselling and education accordingly.

Sexual dimorphism in the adolescent brain: Role of testosterone and androgen receptor in global and local volumes of grey and white matter.

Here we examined sex differences in the volumes of grey and white matter, and in grey-matter "density," in a group of typically developing adolescents participating in the Saguenay Youth Study (n=419; 12-18 years). In male adolescents, we also investigated the role of a functional polymorphism in androgen-receptor gene (AR) in moderating the effect of testosterone on volumes of grey and white matter and grey-matter density. Overall, both absolute and relative volumes of white matter were larger in male vs. females adolescents. The relative grey-matter volumes were slightly larger in female than male adolescents and so was the grey-matter density in a large number of cortical regions. In male adolescents, functional polymorphism of AR moderated the effect of testosterone on relative white- and grey-matter volumes. Following a discussion of several methodological and interpretational issues, we outline future directions in investigating brain-behavior relationships vis-à-vis psychopathology.

Sex differences in the growth of white matter during adolescence.

The purpose of this study was to examine sex differences in the maturation of white matter during adolescence (12 to 18 years of age). We measured lobular volumes of white matter and white-matter "density" throughout the brain using T1-weighted images, and estimated the myelination index using magnetisation-transfer ratio (MTR). In male adolescents, we observed age-related increases in white-matter lobular volumes accompanied by decreases in the lobular values of white-matter MTR. White-matter density in the putative cortico-spinal tract (pCST) decreased with age. In female adolescents, on the other hand, we found only small age-related increase in white-matter volumes and no age-related changes in white-matter MTR, with the exception of the frontal lobe where MTR increased. White-matter density in the pCST also increased with age. These results suggest that sex-specific mechanisms may underlie the growth of white matter during adolescence. We speculate that these mechanisms involve primarily age-related increases in axonal calibre in males and increased myelination in females.

Maternal cigarette smoking during pregnancy and cognitive performance in adolescence.

BACKGROUND: The incidence of cigarette smoking during pregnancy remains high. Maternal smoking during pregnancy is known to be associated with cognitive and behavioural sequelae in childhood and adolescence. We assessed the relationship between maternal cigarette smoking during pregnancy and cognitive abilities in adolescent offspring (n = 503, 12- to 18-years old) using an extensive 6-h battery of tests. METHODS: Non-exposed adolescents (controls) were matched to exposed adolescents (cases) by maternal education and school attended. Cognitive abilities were evaluated using a neuropsychological battery consisting of 33 tasks measuring verbal abilities, visuo-spatial skills, verbal and visual memory, processing speed, resistance to interference and motor dexterity. RESULTS: We found no differences between cases and controls in any of the cognitive domains whether potential confounders were included in the model or not. In addition to maternal smoking during pregnancy, we also evaluated the effect of sex and age on the various cognitive abilities in this large adolescent sample and found that most of the abilities continue to improve during adolescence to the same extent in girls and boys, with several age-independent sex differences. CONCLUSIONS: We found no effect of maternal cigarette smoking during pregnancy on cognitive abilities of the adolescent offspring when matching cases and controls by maternal education, the most common confounder of maternal cigarette smoking during pregnancy.

Corpus callosum in adolescent offspring exposed prenatally to maternal cigarette smoking.

Teratogens, such as alcohol or anti-epileptic drugs, affect the size of the corpus callosum. Here we report findings obtained in a case-control study that investigated possible effects of teratogens contained in cigarette smoke on the size and structural properties of this structure. We recruited and scanned with magnetic resonance imaging a total of 408 adolescents (12 to 18 years of age); a subsample of 300 adolescents is considered in this report. Cases (n=146) were exposed to maternal cigarette smoking during pregnancy; non-exposed controls (n=154) were matched to cases by maternal education. We measured the size of corpus callosum (CC) and its sections (corrected for brain size), as well as mean values of magnetization-transfer ratio (MTR) in each CC section. Corpus callosum, and especially its posterior part, was smaller in the exposed vs. non-exposed female adolescents; no significant effects were found in males. Exposed and non-exposed subjects did not differ in the MTR-based index of myelination in either gender in any CC section. Given the lack of exposure effect on the myelination index, this finding might reflect a lower number of inter-hemispheric connections in female offspring of mothers who smoked during pregnancy.

The correlation of CTG repeat length with material and social deprivation in myotonic dystrophy.

Socioeconomic deprivation has long been recognized as a prominent feature of myotonic dystrophy type 1 (DM1), but studies performed before the discovery of the mutation causing DM1 may have suffered an ascertainment bias towards the more severe forms of the disease. We have sought to clarify the relationship between CTG repeats, muscular impairment, and socioeconomic characteristics of 200 patients with DM1. Patients with DM1 reported lower educational attainment, lower employment rate, lower family income, and higher reliance on social assistance than the reference population. Logistic regression showed, on one hand, that CTG repeats and marital status were significant predictors of social assistance recipiency and, on the other hand, that CTG repeats and gender were significant predictors of low social support from family, after adjustment for age, gender, degree of muscular impairment, CTG repeats, educational level, and marital status. For example, each additional 100 CTG repeats was found to increase the odds of relying on social assistance by about 35% and having low social support by about 22%. The chances of experiencing socioeconomic deprivation are loaded heavily against patients with DM1. The relationship between increased CTG repeat length and higher risk of material and social deprivation must be acknowledged in the clinical management of DM1.

[Myotonic dystrophy: I. Socioeconomic and residential characteristics of the patients]. / La dystrophie myotonique: I. Caractéristiques socio-économiques et résidentielles des malades.

Myotonic dystrophy is a dominantly inherited genetic disorder which, in medical literature, has been linked to peculiar socio-economical conditions. In order to document this assertion, a sociological study was conducted in the Saguenay-Lac-Saint-Jean region (Québec), using a representative sample (N = 218) drawn from the myotonic dystrophy population. A study of the patients' places of residence was also carried out. The results clearly indicate that myotonic dystrophy patients exhibit a socio-economic profile associated with disadvantaged milieux: high unemployment, low income and limited schooling. Many of these patients must rely on social welfare. Two families out of five (42%) live beneath the poverty line. The wage-earning history of these persons is closely linked to their self-evaluation of their working capabilities. After the age of forty, a high proportion of these people are unable to hold down a paying job and claim they are unable to do so. Within a well-screened urban area, a study of the patients' places of residence indicates census tracts where myotonic dystrophy is concentrated (ecological niches). These social areas are close to the downtown area and display characteristics of disadvantaged milieux. Accordingly, the My D gene seems to be confined to a specific socio-economic and socio-geographical environment, through which the spread of the gene is channelled among the population.

[Myotonic dystrophy: II. Marital status, fertility and gene transmission]. / La dystrophie myotonique: II. Nuptialité, fécondité et transmission.

A sociological study, using a representative sample (N = 218) of the myotonic dystrophy population, made possible an analysis of the relationship between certain demographic characteristics (marriage, fertility) and the mechanisms involved in the transmission of the deleterious gene. The results show a clear differentiation between the marriage rate of women and men affected by myotonic dystrophy. Whereas men show a considerable decline in marriage eligibility, women continue to marry at a young age and in a proportion almost equal to that of the unaffected population. The study also indicates that the average fertility rate among married patients in the Saguenay-Lac-Saint-Jean exceeds the fertility rate reported from affected populations found in other countries. Our study shows an above-normal male fertility rate. This demographic fact explains the overrepresentation of male transmitters noted in the affected population. However, if present trends remain unchanged, women will be more likely to transmit myotonic dystrophy to future generations. These conclusions illustrate how the transmission and spread of a dominant gene follow a pattern that cannot be dissociated from the socio-cultural characteristics taken as a whole, particularly demographic characteristics. They also provide us with useful avenues for setting up future prevention programmes.