Early life mental health symptoms and objective health indicators in - PDF document

1 Early life mental health symptoms and objective health indicators in midlife and early old age: Evidence from the 1958 British birth cohort

2 Introduction Major depression and anxiety disorders appear in the top 10 causes of global burden of disease(Vigo, Thornicroft, & Atun), with major depression also being the second leading cause of disability worldwide and a major contributor to the burden of suicide and ischemic heart disease ("Global, regional, and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013," 2015). The public health burden of these common psychological disorders is estimated to continue to increase ("Global, regional, and national incidence, prevalence, and years lived with disability for 301 acute and chronic diseases and injuries in 188 countries, 1990-2013: a systematic analysis for the Global Burden of Disease Study 2013," 2015; Lopez & Murray, 1998). Early life mental health is known to be associated with psychological distress and other mental health phenotypes in adulthood (Clark, Rodgers, Caldwell, Power, & Stansfeld, 2007), as well as socio-economic outcomes (Colman et al., 2009) and the huge costs to society, and to the economy, of poor mental health are undisputed (Layard, 2013) as inequalities due to both social causation and selection are well documented (Goodman, Joyce, & Smith, 2011; C. Power, Stansfeld, Matthews, Manor, & Hope, 2002; Stansfeld, Clark, Rodgers, Caldwell, & Power, 2011). These findings along with those that link early life mental health with less physical activity and more alcohol use in adulthood (Maggs, Patrick, & Feinstein, 2008; PINTO PEREIRA, LI, & POWER, 2015) provide plausible mechanisms of action through which early life mental health may impact on health outcomes in adulthood and consequently the central hypothesis of our study was that early life mental health is associated with objective markers of health in adulthood. Despite these plausible mechanisms of action, there is a paucity of studies documenting the prospective association of early life mental health with objectively measured markers of health in adulthood. Another limitation of the existing literature is that early life mental health is considered at a single time point (Winning, Glymour, McCormick, Gilsanz, & Kubzansky, 2015), therefore neglecting the developmental perspective in the emergence of mental health symptomatology in childhood and adolescence. The development of mental health symptoms through childhood is complex and single time point or population average estimates of symptom development over time

3 can obscure subgroups with different patterns of symptoms (Patalay, Moulton, Goodman, & Ploubidis, 2017). The absence of a single population trend for development in psychopathology across childhood and adolescence is well established and the importance and relevance of studying heterogeneous trajectories of symptom development has been long acknowledged (Patalay et al., 2017). In this paper we capitalise on the availability of three assessments of mental health symptoms in childhood and adolescence and derive a longitudinal typology of early life internalising and externalising symptoms in a population based prospective birth cohort, to investigate their association with objective measures of health and disability in midlife and all – cause mortality by age 55. By doing so we were able to formally empirically test the sensitive/critical period and accumulation of risk hypotheses (Ben- Shlomo, Cooper, & Kuh, 2016) with respect to the development of internalising and externalising symptoms from childhood to adolescence Methods Data The National Child Development Study (NCDS) (C. Power & Elliott, 2006) is the second oldest of the British birth cohort series, with 10 major follow-ups since birth. The initial sample of 17,415 individuals – consisting of all babies born in Great Britain in a single week in 1958 – are now approaching 60 years of age (most recent follow- up at age 55), providing high quality prospective data on social, biological, physical, and psychological phenotypes at every sweep, with 9,279 study members interviewed in person in 2008. In 2002, when respondents were 44-45 years old, a biomedical survey was collected for more than 9,000 respondents. This survey collected objective measures of health, blood samples were collected from 88% of those examined, and 8018 blood samples were received from subjects who gave consent to extraction of DNA. In this work we make use of the biological markers obtained from this survey. Measures Exposure – Early life mental health Externalising and Internalising symptoms in childhood were assessed using the modified version of the Rutter ‘A’ scale (Rutter, Tizard, & Whitmore, 1970). This

4 version of the scale was completed by the mothers of the participants at ages 7 and 11, but from both mother and teachers at 16. Mother and teacher reports were combined. Internalising symptoms include being worried, solitary or miserable, while externalising behaviour includes symptoms such as being disobedient, destructive and/or having poor concentration. Outcomes We included objectively measured health indicators at age 43/44, these were: Fibrinogen : a marker of inflammation and cardiovascular disease (g/L); C-reactive protein : an indicator of inflammation and cardiovascular disease (g/L); Glycated haemoglobin (HbA1c) : index of glucose metabolism over the previous 30− 90 days, which is used as a marker of diabetes mellitus; HDL and LDL cholesterol as markers of cardiometabolic risk; High blood pressure : three measures of systolic and diastolic blood pressure were taken. The mean of valid readings was used, and an individual was recorded as having high blood pressure if the average value was above 140/90; Obesity : the body mass index was calculated using information on height and weight, with obesity defined as a BMI greater than 30; Waist to Hip Ratio (WHR) : waist and hip circumferences were measured and the ratio of waist over hip calculated. To assess respiratory function we used forced expiratory volume (FEV) , with the highest measurement used as a valid one. FEV is a measure of how much air a person can exhale during forced breath during the first second; Disability at age 55 was assessed according to the 2010 equality act; All-cause mortality up to age 55 was recorded by NHS Digital notifications combined with information of the address database held at the Centre for Longitudinal Studies Confounders We included various confounders from ages 0 to 7 that have been previously shown to be associated both with mental health and health in adulthood (Miech, Power, & Eaton, 2007; Chris Power, Jefferis, & Manor, 2010; C. Power et al., 2002; Tabassum et al., 2008). These included birth characteristics: Birthweight; Maternal smoking during pregnancy; Maternal age; Breastfeeding; Parental characteristics: Mother working up to 5; Parents read to child; Parental interest in school; Divorce; Separation from child; Indicators of Socio Economic Position: Paternal social class at birth; Financial difficulties; Age mother stayed at school; Housing tenure; Access to