Diane J. Bamber

The Subjective and Cognitive Effects of Acute Phenylalanine and Tyrosine Depletion in Patients Recovered from Depression

Although there is evidence for the involvement of dopamine (DA) in unipolar depression, no published study has yet used the technique of acute phenylalanine and tyrosine depletion (APTD), a dietary intervention that selectively lowers DA synthesis, in order to investigate the role of DA in mood disturbance. Tyrosine and phenylalanine depleted and placebo amino acid drinks were administered to 20 patients recovered from depression in a double-blind, placebo-controlled, crossover design. Measures included subjective effects, Hamilton Depression Rating Scale scores, and a comprehensive battery of well-validated computerized cognitive tests. APTD induced a substantial reduction in the ratio of plasma tyrosine and phenylalanine to large neutral amino acids. However, relapse of depressive symptoms was not seen. Although performance on most cognitive tests was unaffected, there was a selective effect on decision-making, with APTD causing participants to bet significantly less. In conclusion, These results suggest a specific role for the involvement of DA in reward/punishment processing in humans. While APTD did not induce relapse in any participant, it did cause patients recovered from depression to show lowered sensitivity to reward in a gambling game. It is hypothesized that tests involving reward/punishment processing are preferentially affected by DA depletion, and that a more complete account of depression is likely to result from considering the roles played by serotonin, noradrenaline, and DA in mediating the various cognitive and clinical symptoms, including anhedonia.

Breakfast consumption and physical activity in British adolescents

Studies show an inverse relationship between breakfast frequency and weight gain. This may reflect poor eating habits generally and associated low physical activity (PA) or direct impacts of breakfast on mechanisms leading to lethargy and reduced PA. The relationship between breakfast frequency and PA is inconclusive. We aimed to determine whether breakfast frequency is associated with PA levels in British adolescents independent of body composition and socio-economic status (SES). Habitual breakfast frequency (self-report questionnaire) was assessed in 877 adolescents (43% male, age 14·5 (SD 0·5) years old). PA was measured over 5 d (accelerometry, average counts/ min; cpm). Associations between daily PA and breakfast frequency were assessed using linear regression adjusted for body fat percentage and SES. Effect modification by sex and associations with PA during the morning (06.00-12.00 hours) were explored. For boys, there were no significant associations between breakfast frequency and PA. For girls, less frequent breakfast consumption was significantly associated with lower PA (cpm) during the morning (occasional v. frequent b - 6·1 (95% CI - 11·1, -1·1), P = 0·017) when adjusted for body fat percentage and SES. There were no associations between PA and breakfast consumption over the whole day; however, for girls, less frequent breakfast consumption may be associated with lower PA levels during the morning, suggesting that breakfast consumption should perhaps be taken into consideration when aiming to promote PA in adolescent girls.

Physical Activity Awareness of British Adolescents.

OBJECTIVES To assess adolescent physical activity (PA) awareness and to investigate associations with biologic and psychosocial factors. DESIGN Cross-sectional study from November 1, 2005, through July 31, 2007 (the ROOTS study). SETTING Population-based sample recruited from Cambridgeshire and Suffolk schools (United Kingdom). PARTICIPANTS Of 799 participants, 43.6% were male. The mean (SD) age was 14.5 (0.5) years. MAIN EXPOSURES Self-rated PA perception, self-reported psychosocial factors, and measured anthropometry. MAIN OUTCOME MEASURES We measured PA with accelerometry for 5 days. Inactive was defined as less than 60 minutes per day of moderate and vigorous PA (MVPA) measured by accelerometry. Associations between awareness (agreement between self-rated and accelerometry-measured active/inactive) and potential correlates were investigated using multinomial logistic regression. RESULTS Approximately 70.1% of adolescents were inactive (81.2% of girls and 55.8% of boys; odds ratio [OR], 3.41; 95% confidence interval [CI], 2.41-4.82). There were 52.6% of all girls (64.8% of inactive girls) and 33.6% of all boys (60.3% of inactive boys) who inaccurately rated themselves as active (overestimators). Compared with girls accurately describing themselves as inactive (28.6%), girl overestimators had lower fat mass (OR, 0.84; 95% CI, 0.70-0.99), higher socioeconomic status (high vs low OR, 2.38; 95% CI, 1.07-5.32), more parent support (OR, 1.57; 95% CI, 1.12-2.22), and better family relationships (OR, 0.25; 95% CI, 0.09- 0.67). Among boys accurately describing themselves as inactive (22.1%), overestimators had lower fat mass (OR, 0.86; 95% CI, 0.77-0.96) and reported more peer support (OR, 1.75; 95% CI, 1.32-2.30) and less teasing (OR, 0.75; 95% CI, 0.61-0.92). CONCLUSIONS A substantial number of adolescents believe themselves to be more physically active than they really are. They may be unaware of potential health risks and unlikely to participate in PA promotion programs. Increasing information of PA health benefits beyond weight control might encourage behavior change.

Prospective associations between sedentary time, sleep duration and adiposity in adolescents

Highlights • We examined sedentary time and sleep length relative to changes in youth adiposity.• Sedentary time was not associated with change in adiposity in either gender.• Sleep duration was significantly inversely associated with adiposity gain in boys.• The association for sleep in boys was attenuated by physical activity and depression.

The quality of midday meals eaten at school by adolescents; school lunches compared with packed lunches and their contribution to total energy and nutrient intakes.

OBJECTIVE To compare food and nutrient intakes from midday meals provided by schools with those from packed lunches and to estimate the contribution from food eaten at midday to the total daily energy and nutrient intakes of teenagers. DESIGN Dietary data were recorded in 4 d estimated diaries of which 2 d were school days. The school day data were analysed for total and midday energy and nutrient intakes. The latter were compared with the recommendations of the Caroline Walker Trust (CWT). SETTING Cambridgeshire, UK, 2006. SUBJECTS Teenagers (n 757) aged 14-15 years, from eighteen secondary schools, who reported food eaten at school. RESULTS The contribution to total daily energy intake from all lunches eaten at school was 29 % (boys) and 28 % (girls). School meals provided greater quantities of protein, starch, carotene and folate but also more saturated fats and Na than packed lunches. Intakes of energy and several nutrients fell below the CWT recommendations for both types of lunch. School meals and packed lunches provided different types of foods; greater quantities of rice, pasta and vegetables in school meals; more yoghurt, cheese, fruit and juices but also more confectionery and soft drinks in packed lunches. CONCLUSIONS There has been concern that schoolchildren who are not opting for lunch provided by schools are compromising the overall quality of their diet, but the present study showed small differences in nutrient content between packed and school lunches. These data were collected in 2005–2007 before the government programme of improvements reached secondary schools.

Is wearing a pedometer associated with higher physical activity among adolescents

Objective To examine whether wearing a pedometer was associated with higher objectively-measured physical activity (PA) among adolescents independent of other behavior change strategies, and whether this association differed by sex or day of wear. Method In a parallel-group population-based cohort study, 892 adolescents (43.4% male, mean ± SD age, 14.5 ± 0.5 years) from Eastern England were recruited. PA was measured (in 2005–2006) by accelerometry over four days; a sub-group (n = 345) wore a pedometer coterminously with the accelerometer. Three-level (individual, day of wear and school level) multiple linear regression was used to examine the association between accelerometry (counts/min, cpm) and pedometer wear, stratified by sex and adjusted for weekday/weekend. Results For the entire cohort, there was a significant decline in cpm over four days (p < 0.01). Girls wearing pedometers had higher mean cpm than those not wearing a pedometer, independent of BMI z-score, socio-economic status, weekday/weekend, and school clustering (β = 5.1; 95% CI: 0.8 to 9.5, p = 0.02). This association was not seen in boys. Conclusion Pedometer wear was associated with higher PA among adolescent girls, but not boys. Findings may support sex-specific intervention strategies. In addition to pedometer monitoring, additional strategies may be required to promote PA levels, especially among boys.

Breakfast consumption and physical activity in adolescents: daily associations and hourly patterns

Background: The association between breakfast consumption and physical activity (PA) is inconclusive. Objective: We aimed to investigate daily associations and hourly patterns of PA and breakfast consumption in British adolescents. Design: Daily PA [accelerometry-derived moderate and vigorous physical activity (MVPA)] and breakfast consumption (diet diary) were measured simultaneously over 4 d in 860 adolescents (boys: 43.4%; mean ± SD age: 14.5 ± 0.5 y). Associations between MVPA and breakfast consumption were assessed by using a multilevel mixed-effects logistic regression separately by sex and for weekends and weekdays. Hourly patterns of MVPA by breakfast consumption status were displayed graphically, and differences were tested by using ANOVA. Multilevel linear regression was used to investigate differences in log MVPA on days when 570 inconsistent breakfast consumers ate or skipped breakfast. Results: On weekends, boys and girls with higher MVPA were more likely to eat breakfast [OR (95% CI): boys, 1.78 (1.30, 2.45) (P < 0.001); girls, 2.30 (1.66, 3.08) (P < 0.001)] when adjusted for socioeconomic status, percentage of body fat, and total energy intake. Peak hourly MVPA differed for breakfast consumers compared with nonconsumers on weekends (P < 0.001). Inconsistent breakfast consumers did more MVPA on days when they ate breakfast [exponentiated β coefficients (95% CIs): 1.2 (1.0, 1.5) on weekdays and 1.4 (1.1, 1.8) on weekends for boys and 1.6 (1.3, 2.1) on weekends for girls; all P < 0.03]. Conclusions: Eating breakfast was associated with higher MVPA on weekends. The time of peak MVPA differed between breakfast consumers and nonconsumers on weekends. Breakfast consumption at weekends is worth additional investigation to potentially inform PA promotion in adolescents.

Perceived family functioning and friendship quality: cross-sectional associations with physical activity and sedentary behaviours

BackgroundThis study examined the association of adolescent-reported family functioning and friendship quality with objectively-measured moderate to vigorous physical activity (MVPA), sedentary time, and self-reported sedentary behaviours.MethodsData are from the ROOTS study. MVPA and sedentary time were assessed using combined movement and heart rate sensing. Time spent TV viewing, using the internet, playing video games, doing homework and reading for pleasure was self-reported. Data on objectively-measured and self-reported outcomes for weekdays was available for 738 (age 14.5y, 55.7% female) and 800 (56.3% female) participants, respectively. Adolescents perceived family functioning and friendship quality (Two subscales: ‘Good friendship qualities’, ‘Friendship difficulties’) was assessed by questionnaire. Analyses were conducted using multi-level linear or logistic regression.ResultsAdolescents reporting better family functioning accumulated more MVPA on weekdays (beta; 95% confidence interval: 0.57; 0.17,0.98). Higher scores on the good friendship qualities subscale was associated with greater MVPA throughout the week (weekdays: 1.13; 0.62,1.65, weekend: 0.56; 0.09,1.02) and lower sedentary time on weekdays (−10.34; −17.03,-3.66). Boys from better functioning families were less likely to report playing video games at the weekend (OR; 95% confidence interval: 0.73; 0.57,0.93) or reading for pleasure (weekday: 0.73; 0.56,0.96 weekend: 0.75; 0.58,0.96). Boys who attained higher scores on the good friendship qualities scale were less likely to play video games at the weekend (0.61; 0.44,0.86) or report high homework on weekdays (0.54; 0.31,0.94). A higher score for good friendship qualities was associated with lower odds of girls playing video games during the week (0.76; 0.58,1.00) or reading for pleasure at the weekend (0.61; 0.42,0.88). Girls that reported fewer friendship difficulties had lower odds of high TV viewing (0.76; 0.62,0.93) or playing video games (0.71; 0.52,0.97) at the weekend, and lower odds of reading for pleasure (0.63; 0.49,0.81) or reporting high homework on weekdays (0.70; 0.52,0.95).DiscussionFamily functioning and friendship quality exhibit a complex pattern of association with physical activity and sedentary behaviour that varies by sex and day of the week. Findings highlight the potential value of targeting interpersonal aspects of the family and friendships as an adjunct to behaviour change interventions.

Objectively measured physical activity and longitudinal changes in adolescent body fatness: an observational cohort study.

The data regarding prospective associations between physical activity (PA) and adiposity in youth are inconsistent.

The value of lunch provided by schools in relation to the total diet of teenagers

In England approximately 3 · 10 school meals are served each day. The National Diet and Nutrition Survey (NDNS) of 4–18 year olds in 1997 reported that these meals contribute between one-quarter and one-third of the daily intake of energy, fat, dietary fibre, Fe, Ca, vitamin C and folate. The report found that the typical diet of UK children was not balanced, with many children consuming high levels of saturated fat, Na and sugars and low amounts of Zn, Ca, Fe, vitamin A and NSP. Evidence from a recent survey also suggests that school meals are increasingly catering for children’s liking of high-fat foods, as 48% of schoolchildren surveyed chose foods such as chips or burgers at lunchtime. This finding has resulted in an increased concern about the quality of school lunches, which have been the subject of much criticism in the media. In 2005 the government responded to these concerns by introducing new foodand nutrient-based standards for school meals, which focused on changing the eating habits of young individual. Information was collected on the diets of 933 teenagers, aged 14–15 years, across nineteen schools in Cambridgeshire during 2005–7. All food and drinks consumed over a 4 d period, including two weekdays and two weekend days, were recorded in a food diary. The diets were coded and analysed using the in-house food composition database that is based on McCance and Widdowson’s Composition of Foods. Results presented are for 393 pupils who ate food provided by schools, either on one or both of the school days recorded; a total of 612 school lunches.