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Biomedical subjects

David A Leon

Publications and source records attributed to David A Leon.

At least 37 records · Page 2Linked to original sources
PubMed2005

Early life factors, childhood cognition and postal questionnaire response rate in middle age: the Aberdeen Children of the 1950s study.

BACKGROUND: Little is known about the relationship between early life factors and survey response in epidemiological studies of adults. METHODS: The Children of the 1950s cohort is composed of 12,150 children (boys 51.7%) born in Aberdeen 1950-56 and in primary schools in the city in 1962. Information on birth weight, gestational age, growth, behaviour and socio-economic position at birth and in childhood were obtained from contemporaneous records. Cognitive test scores at ages 7,9 and 11 years were also available from school records. The outcome was response to a postal questionnaire sent (2001-2003) to surviving cohort members in middle age. RESULTS: Of 11,282 potentially mailed subjects, 7,183 (63.7%) returned questionnaires. Response rates were highest among females, and those whose parents were married at birth, were in a non-manual social class at birth or in childhood, had fewer siblings, were taller and heavier in childhood for their age and had lower Rutter B behavioural scores. Childhood cognitive test scores at every age were strongly and positively related to the response rate to a postal questionnaire independently of other early life factors monotonically across the entire range of test scores. Those in the bottom fifth at age 11 had a response rate of 49% while those in the top fifth 75%. CONCLUSION: The strength and consistency of the association of childhood cognition with questionnaire response rate in middle age is surprisingly large. It suggests that childhood cognition across the entire normal range is a powerful influence on the complex set of later behaviours that comprise questionnaire response. The extent of possible response bias in epidemiological studies of the associations between childhood characteristics (particularly those related to cognition) and later health is probably larger than is generally realised, at least in situations where the survey instrument is a postal questionnaire.

Child↗
PubMed2005

Association of body mass index and obesity measured in early childhood with risk of coronary heart disease and stroke in middle age: findings from the aberdeen children of the 1950s prospective cohort study.

BACKGROUND: There is concern that the childhood epidemic of obesity will result in increases in the risk of cardiovascular disease in the future; however, there is currently little direct evidence on this issue. METHODS AND RESULTS: We assessed the association of body mass index, measured when subjects were a mean age of 4.9 years old, with the future risk of coronary heart disease (CHD) and stroke in a large Scottish birth cohort (born in the 1950s) who have been linked to hospital admissions and mortality data. At the start of the follow-up period (1981), there were 11,106 (91%) members of the cohort alive and believed to be resident in Scotland. Over the follow-up period, they contributed 245,000 person-years of risk. Among these subjects, there were 302 (53 fatal) cases of CHD, 109 (4 fatal) cases of stroke, and 397 (57 fatal) cases of either a CHD or stroke. There was no association between childhood body mass index and CHD risk. There was no linear association between childhood body mass index and stroke risk, but those who were obese in childhood (top 2.5% of the body mass index distribution) compared with all others had an increased risk of stroke; the adjusted (for gender, father's occupational social class at birth, number of siblings, and birth weight) hazards ratio was 2.41 (95% CI 1.00 to 5.86). CONCLUSIONS: Body mass index in early childhood does not appear to be associated with increased CHD risk in later life.

Body Mass Index↗
PubMed2005

World mortality 1950-2000: divergence replaces convergence from the late 1980s.

OBJECTIVE: We sought to investigate to what extent worldwide improvements in mortality over the past 50 years have been accompanied by convergence in the mortality experience of the world's population. METHODS: We have adopted a novel approach to the objective measurement of global mortality convergence. The global mortality distribution at a point in time is quantified using a dispersion measure of mortality (DMM). Trends in the DMM indicate global mortality convergence and divergence. The analysis uses United Nations data for 1950-2000 for all 152 countries with populations of at least 1 million in 2000 (99.7% of the world's population in 2000). FINDINGS: The DMM for life expectancy at birth declined until the late 1980s but has since increased, signalling a shift from global convergence to divergence in life expectancy at birth. In contrast, the DMM for infant mortality indicates continued convergence since 1950. CONCLUSION: The switch in the late 1980s from the global convergence of life expectancy at birth to divergence indicates that progress in reducing mortality differences between many populations is now more than offset by the scale of reversals in adult mortality in others. Global progress needs to be judged on whether mortality convergence can be re-established and indeed accelerated.

Global Health↗
PubMed2005

Age at menarche and adult BMI in the Aberdeen children of the 1950s cohort study.

BACKGROUND: Few studies have examined whether the inverse association of age at menarche with adult body mass index (BMI) is due to the tendency of BMI to track between childhood and adult life, with childhood BMI playing a causal role in determining age at menarche. OBJECTIVE: The objective was to investigate whether the association of younger age at menarche with a high BMI and increased likelihood of obesity in middle age is due to confounding with early childhood BMI. DESIGN: In a historical cohort of 3743 Scottish females born between 1950 and 1955, height and weight were measured in early childhood, and age at menarche and height and weight in middle age were obtained by questionnaire. RESULTS: The age-adjusted change in mean adult BMI per additional year of age at menarche was -0.64 (95% CI: -0.78, -0.50). Adjustment for childhood BMI measured between 4 and 6 y reduced this value to -0.57 (-0.71, -0.43). Adjustment for childhood and adult social class, parity, smoking, and alcohol intake had little effect. The odds ratio for being obese compared with not being obese in adulthood was 0.82 (0.76, 0.86) per 1-y increase in age at menarche and was unchanged by adjustment for childhood BMI and other covariates. CONCLUSIONS: The inverse association of age at menarche with BMI and obesity in middle age is not explained by confounding by early childhood BMI. Instead, age at menarche may simply be a proxy marker for the pace of sexual maturation, which itself leads to differences in adiposity (and BMI) in the peripubertal period that track into adult life.

Adolescent↗
PubMed2005

The composition of surrogate alcohols consumed in Russia.

BACKGROUND: In the course of a case-control study examining determinants of premature death among working age men, it became clear that a significant percentage of the population (7.3%) were drinking a variety of surrogate alcohol products (products not legally sold for consumption). In this population, where there is a high death rate from alcohol-related causes, including acute alcohol poisoning, it was important to know what these products contained. METHODS: The identity of products being consumed was identified from the survey of controls. Representative samples were obtained and subjected to analysis using gas chromatography and mass spectrometry to determine their composition. RESULTS: Three broad groups of product were identified: samogon (home-produced spirits); medicinal compounds; and other spirits (mainly sold as aftershaves). Commercially produced vodkas were used for comparison. Samogon contained lower quantities of ethanol than vodka [mean, 39 vs. 44 volumetric percentage (v/v%), respectively] but in addition contained certain toxic long-chain alcohols. Medicinal compounds contained only ethanol, at a higher concentration that vodka (mean, 66 v/v%), while the other spirits, which were also essentially pure ethanol, contained a mean of 94 v/v%. CONCLUSIONS: A significant number of Russian men are drinking products that have either very high concentrations of ethanol or contaminants known to be toxic. These products are untaxed and thus much less expensive than vodka. There is an urgent need for policy responses that target their production and consumption.

1-Propanol↗
PubMed2005

Morning cortisol does not mediate the association of size at birth with blood pressure in children born from full-term pregnancies.

OBJECTIVE: It had been suggested that programming of the hypothalamo-pituitary-adrenal axis may underlie the associations of reduced size at birth with raised blood pressure in later life. We investigated whether morning salivary cortisol mediates the inverse association of birthweight with systolic blood pressure in children. DESIGN: Subjects and measurements--a historical cohort study involving 1152 Swedish children aged 5-14 years, who took part in a family study comprised of mother, father, and two full-sibs delivered in 1987-1995 after 38-41 weeks gestation within 36 months of each other. Birthweight and gestational age were available from obstetric records. Blood pressure, weight, height and puberty stage were measured at a clinic. Cortisol was measured by radioimmunoassay in morning salivary samples taken at home, within 30 min of waking. RESULTS: Morning cortisol showed a weak negative association with length of gestation in siblings, was not related to birthweight or to systolic or diastolic blood pressure. There was no change in the strength of the negative association between birthweight and systolic blood pressure on adjustment for cortisol (-1.4 mmHg/kg, 95% CI -2.7, -0.2; adjusted for age, sex, puberty stage, weight and height, and cortisol). CONCLUSIONS: Morning cortisol was not associated with size at birth, and did not mediate the birthweight-blood pressure association in children born from full-term pregnancies. It is possible that basal cortisol levels are of more importance in explaining associations of size at birth with later blood pressure in older subjects, or in populations with more varied length of gestation. Alternatively, our results may be caused by misclassification of the hypothalamo-pituitary-adrenal activity.

Adolescent↗
PubMed2005

The association of ambient outdoor temperature throughout pregnancy and offspring birthweight: findings from the Aberdeen Children of the 1950s cohort.

BACKGROUND: We assessed the effect of mean ambient outdoor temperature during gestation on birthweight. OBJECTIVE: To assess the effect of mean ambient outdoor temperature during gestation on birth weight. DESIGN: Birth cohort study with record linkage to climate databases. SETTING: Aberdeen, Scotland. SAMPLE: A total of 12,150 individuals born in Aberdeen, Scotland between 1950 and 1956. METHODOLOGY/PRINCIPAL FINDINGS: Perinatal data from a cohort of 12,150 individuals born in Aberdeen, Scotland between 1950 and 1956 were linked to daily outdoor temperature data. Birthweight was seasonally patterned, with lowest birthweights among those born in the winter months (December-February) and highest birthweights among those born in the autumn months (September-November); P= 0.01 for joint sine-cosine functions. Mean ambient outdoor temperature during the first trimester of pregnancy was inversely associated with birthweight and mean ambient outdoor temperature during the third trimester of pregnancy was positively associated with birthweight. In fully adjusted (for sex, maternal age, birth year, birth order and social class) models a 1 degrees C increase in mean ambient outdoor temperature in the mid 10-day period of the first trimester was associated with a 5.4-g (95% confidence interval [CI] 2.9, 7.9 g) decrease in birthweight, whereas a 1 degrees C increase in the mid 10-day period of the third trimester was associated with a 1.3-g (95% CI 0.50, 2.1 g) increase in birthweight. Ambient outdoor temperature in the first trimester of pregnancy explained the seasonal patterning of birthweight. MAIN OUTCOME MEASURE: Birthweight. RESULTS: Birthweight was seasonally patterned, with lowest birthweights among those born in the winter months (December-February) and highest birthweights among those born in the autumn months (September-November); P= 0.01 for joint sine-cosine functions. Mean ambient outdoor temperature during the first trimester of pregnancy was inversely associated with birthweight and mean ambient outdoor temperature during the third trimester of pregnancy was positively associated with birthweight. In fully adjusted (for sex, maternal age, birth year, birth order and social class) models a 1 degrees C increase in mean ambient outdoor temperature in the mid 10-day period of the first trimester was associated with a 5.4 g (95% confidence interval 2.9, 7.9 g) decrease in birthweight, whereas a 1 degrees C increase in the mid 10-day period of the third trimester was associated with a 1.3 g (95% confidence interval 0.50, 2.1 g) increase in birthweight. Ambient outdoor temperature in the first trimester of pregnancy explained the seasonal patterning of birthweight. CONCLUSION: Higher ambient outdoor temperature in the first trimester of pregnancy and/or lower ambient outdoor temperature in the third trimester are associated with reduced offspring birthweight. With the increasing occurrence of temperature extremes, in particular, heat waves, these findings, if replicated in other studies, have important public health implications.

Adolescent↗
PubMed2005

Socio-economic position across the life course and hysterectomy in three British cohorts: a cross-cohort comparative study.

OBJECTIVE: To examine the association between indicators of lifetime socio-economic position and rates of hysterectomy in three British cohorts. DESIGN: Cross-cohort comparative study. SETTING: Two cohorts: England, Scotland and Wales. Third cohort: Aberdeen, Scotland. POPULATION: Three thousand two hundred and eight women born between 1919 and 1940, participating in the British Women's Heart and Health Study (BWHHS); 1394 women from the MRC National Survey of Health and Development (NSHD), followed up since birth in 1946; 3208 women born between 1950 and 1955, participating in the Aberdeen Children of the 1950s study, all with complete information on lifetime socio-economic position and hysterectomy status. METHODS: Relative indices of inequality were derived for markers of socio-economic position in childhood and adulthood. Cox's regression models were used to test the association between these markers and hysterectomy. MAIN OUTCOME MEASURE: Self-reported hysterectomy with or without oophorectomy. RESULTS: Adverse socio-economic position in childhood and as indicated by educational status was associated with reduced rates of hysterectomy in the oldest of the three cohorts (BWHHS), whereas conversely in the NSHD and Aberdeen cohorts it was associated with increased rates of hysterectomy. The unadjusted hazards ratios for hysterectomy comparing worst to best socio-economic position for father's social class were 0.73 (0.56, 0.96) for women from the BWHHS, 1.77 (1.19, 2.65) for those from the NSHD and 2.06 (1.46, 2.89) for those from the Aberdeen cohort. Associations between markers of adult socio-economic position and hysterectomy tended to be weaker in all three cohorts and often did not reach conventional levels of statistical significance. CONCLUSIONS: Our results show that hysterectomy rates are influenced by childhood socio-economic position and educational attainment, but that the nature of this association varies across these three British cohorts born in different decades of the 20th century. That there were no consistent or strong associations between adult SEP and hysterectomy rates suggest that social factors influencing rates of hysterectomy are likely to be those experienced or which develop in early life rather than those which develop later.

Adult↗
PubMed2005

Association between childhood and adulthood socioeconomic position and pregnancy induced hypertension: results from the Aberdeen children of the 1950s cohort study.

BACKGROUND: Pregnancy induced hypertension may indicate a tendency towards endothelial and metabolic abnormalities leading to future cardiovascular disease. Childhood socioeconomic adversity is associated with increased cardiovascular disease risk but the association with pregnancy induced hypertension is unknown. AIM: To examine the association of childhood and adulthood socioeconomic position with pregnancy induced hypertension. DESIGN: Historical cohort study with record linkage to obstetric data. SUBJECTS: 3485 women who were born in Aberdeen between 1950 and 1956 and delivered 7080 viable singleton offspring in the period up until to 1999. MAIN OUTCOME MEASURE: Pregnancy induced hypertension (pre-eclampsia and gestational hypertension) in these women's pregnancies. RESULTS: Neither childhood nor adulthood socioeconomic position were associated with either pre-eclampsia or gestational hypertension. The fully adjusted odds ratio (95% confidence interval) comparing those born in manual social classes to those born in non-manual social classes for pre-eclampsia was 1.10 (0.72 to 1.73) and for gestational hypertension was 1.02 (0.83 to 1.32). Similar results comparing women in manual with non-manual social classes classified at the time of each pregnancy were 1.09 (0.73 to 1.67) for pre-eclampsia and 0.99 (0.81 to 1.30) for gestational hypertension. CONCLUSION: Although imprecise these results suggest that neither childhood nor adulthood socioeconomic adversity is associated with pregnancy induced hypertension.

Adult↗
PubMed2005

Early life predictors of childhood intelligence: evidence from the Aberdeen children of the 1950s study.

OBJECTIVE: To identify the early life predictors of childhood intelligence. DESIGN: Cohort study of 10 424 children who were born in Aberdeen (Scotland) between 1950 and 1956. RESULTS: Social class of father around the time of birth, gravidity, maternal age, maternal physical condition, whether the child was born outside of marriage, prematurity, intrauterine growth, and childhood height were all independently associated with childhood intelligence at ages 7, 9, and 11. The effect of social class at birth was particularly pronounced, with a graded linear association across the distribution even with adjustment for all other covariates (p<0.001 for linear trend). Those from the lowest social class (V) had intelligence scores that were on average 0.9-1.0 of a standard deviation lower than those from the higher groups (I and II) at each of the three ages of intelligence testing. Collectively, the early life predictors that were examined explained 16% of the variation in intelligence at each age. CONCLUSIONS: Father's social class around the time of birth was an important predictor of childhood intelligence, even after adjustment for maternal characteristics and perinatal and childhood factors. Studies of the association of childhood intelligence with future adult disease need to ensure that the association is not fully explained by socioeconomic position.

Adult↗
PubMed2005

Accuracy of adults' recall of childhood social class: findings from the Aberdeen children of the 1950s study.

BACKGROUND: Although adult reported childhood socioeconomic position has been related to health outcomes in many studies, little is known about the validity of such distantly recalled information. This study evaluated the validity of adults' reports of childhood paternal social class. METHODS: Data are drawn from the Aberdeen children of the 1950s study, a cohort of 12 150 people born in Aberdeen (Scotland) who took part in a school based survey in 1962. In this survey, two indices of early life socioeconomic position were collected: occupational social class at birth (abstracted from maternity records) and occupational social class in childhood (reported during the 1962 survey by the study participants). Between 2000 and 2003, a questionnaire was mailed to traced middle aged cohort members in which inquiries were made about their fathers' occupation when they were aged 12 years. The level of agreement between these reports and prospectively collected data on occupational social class was assessed. RESULTS: In total, 7183 (63.7%) persons responded to the mid-life questionnaire. Agreement was moderate between social class of father recalled in adulthood and that measured in early life (kappa statistics were 0.47 for social class measured at birth, and 0.56 for social class reported by the child). The relation of occupational social class to birth weight and childhood intelligence was in the expected directions, although weaker for adults' reports in comparison with prospectively gathered data. CONCLUSIONS: In studies of adult disease aetiology, associations between childhood social class based on adult recall of parental occupation and health outcomes are likely to underestimate real effects.

Birth Weight↗
PubMed2005

Birth weight and psychological distress at age 45-51 years: results from the Aberdeen Children of the 1950s cohort study.

BACKGROUND: It is unclear whether the effect of low birth weight on common affective disorders in later life is direct or mediated through childhood factors. AIMS: To determine whether birth weight has a direct effect on psychological distress in adulthood not mediated by childhood IQ or behavioural problems. METHOD: Participants (n=5572) of the Aberdeen Children of the 1950s study had data on birth weight for gestational age and adult psychological distress. Logistic regression was used to examine the association between these factors, with adjustment for confounders and potential childhood mediators. RESULTS: Children born full term but weighing less than 5.5 lb had increased odds of psychological distress in later life after adjustment for potential confounders (OR=1.49, 95% CI 1.01-2.20). Further adjustment for childhood IQ and behaviour did not attenuate the association. A 1 s.d. decrease in birth weight for gestational age was associated with a 4% increased odds of psychological distress in adulthood (OR=1.04, 95% CI 0.97-1.12). CONCLUSIONS: Low birth weight for gestational age, particularly at term, was associated with adult psychological distress. This was not mediated by childhood factors, suggesting a direct effect of early life factors on adult mental health. A neurodevelopmental pathway may therefore be implicated.

Birth Weight↗
PubMed2005

Childhood socioeconomic position, educational attainment, and adult cardiovascular risk factors: the Aberdeen children of the 1950s cohort study.

OBJECTIVES: We assessed the associations of childhood socioeconomic position with cardiovascular disease risk factors (smoking, binge alcohol drinking, and being overweight) and examined the roles of educational attainment and cognitive functioning in these associations. METHODS: Data were derived from a cohort study involving 7184 individuals who were born in Aberdeen, Scotland, between 1950 and 1956; had detailed records on perinatal characteristics, childhood anthropometry, and cognitive functioning; and responded to a mailed questionnaire when they were aged 45 to 52 years. RESULTS: Strong graded associations existed between social class at birth and smoking, binge drinking, and being overweight. Adjustment for educational attainment completely attenuated these associations. However, after control for adult social class, adult income and other potential confounding or mediating factors, some association remained. CONCLUSIONS: Educational attainment is an important mediating factor in the relation between socioeconomic adversity in childhood and smoking, binge drinking, and being overweight in adulthood.

Cardiovascular Diseases↗
PubMed2004

Paternal age and schizophrenia: a population based cohort study.

OBJECTIVE: To investigate the association of paternal age at conception with the risk of offspring developing schizophrenia. DESIGN: A population based cohort study. SETTING: Sweden. SUBJECTS: 754,330 people born in Sweden between 1973 and 1980 and still alive and resident in Sweden at age 16 years. MAIN OUTCOME MEASURES: Hospital admission with schizophrenia or non-schizophrenic, non-affective psychosis. RESULTS: After adjustment for birth related exposures, socioeconomic factors, family history of psychosis, and early parental death the overall hazard ratio for each 10 year increase in paternal age was 1.47 (95% confidence interval 1.23 to 1.76) for schizophrenia and 1.12 (0.98 to 1.29) for non-schizophrenic non-affective psychosis. This association between paternal age and schizophrenia was present in those with no family history of the disorder (hazard ratio for each 10 year increase in paternal age 1.60, 1.32 to 1.92), but not in those with a family history (0.91, 0.44 to 1.89) (P = 0.04 for interaction). CONCLUSIONS: Advancing paternal age is an important independent risk factor for schizophrenia. The stronger association between paternal age and schizophrenia in people without a family history provides further evidence that accumulation of de novo mutations in paternal sperm contributes to the overall risk of schizophrenia.

Adolescent↗
PubMed2004

Separating within and between effects in family studies: an application to the study of blood pressure in children.

In epidemiology the analyses of family or twin studies do not always fully exploit the data, as information on differences between siblings is often used while between-families effect are not considered. We show how cross-sectional time-series linear regression analysis can be easily implemented to estimate within- and between-families effects simultaneously and how these effects can then be compared using the Hausman test. We illustrate this approach with data from the Uppsala family study on blood pressure in children with age ranging from 5.5 to 12.3 years for the younger and from 7.5 to 13.8 years for the older siblings. Comparing the effect of differences in birth weight on blood pressure within-family (in full siblings) and between-families (in unrelated children) allows us to study the contributions of fixed and pregnancy-specific maternal effects on birth weight and consequently on blood pressure. Our data showed a 0.88 mmHg decrease (95 per cent confidence interval: -1.7 to -0.03 mmHg) in systolic blood pressure for one standard deviation increase in birth weight between siblings within a family and 0.88 mmHg (95 per cent confidence interval: -1.6 to -0.2 mmHg) decrease in systolic blood pressure for one standard deviation increase in birth weight between unrelated children. These estimates were controlled for sex, age, pubertal stage, body size and pulse rate of the children at examination and for maternal body size and systolic blood pressure. The within- and between-families effects were not significantly different, p = 0.19, suggesting that fixed and pregnancy-specific factors have similar effects on childhood systolic blood pressure.

Adolescent↗