The influence of lifestyle factors on the relationship between childhood adversities and comorbid mental and physical health problems

Abstract

The comorbidity of mental and physical health problems (i.e., mental-physical comorbidity) exacerbates the functional impairment and healthcare burden above that of each health problem alone. As common risk factors, childhood adversities have recently shown to elevate the risk of mental-physical comorbidity in both children and adults. This presents additional complications for individuals exposed to childhood adversities, but also offers an opportunity for researchers to identify factors which mitigate mental-physical comorbidity in a population with heightened risk. Known to have common protective qualities on mental and physical health, modifiable lifestyle behaviours were chosen as candidate moderators. Their influence was examined on the association between childhood adversities and mental-physical comorbidity, as well as on individual mental and physical health problems, to highlight protective behaviours which mitigate elevated health risks. The studies encompassed three distinct age groups which covered key stages across human life course.

In the first empirical chapter, a Mediterranean diet pattern, physical activity, and sleep duration were investigated as moderators of the association between early life stress and early markers of health problems in childhood (mean age: 14 years), including high internalising symptoms, high fat mass, and their comorbidity. Analyses were conducted on samples from two European birth cohort studies, the Avon Longitudinal Study of Parents and Children (ALSPAC; n = 8,426) and Generation R (GenR; n = 4,268). None of the examined lifestyle factors significantly moderated these associations in either cohort. However, regular physical activity reduced the odds of high internalising symptoms by 17% in ALSPAC and 10% in GenR at average exposure to early life stress, confirming the general benefits of regular physical activity on childhood mental health.

The second empirical chapter investigated the moderating effects of lifestyle factors on the association between childhood maltreatment and depression, cardiometabolic disease, and their comorbidity in mid-late adulthood (mean age: 56 years). Five self-reported measures of lifestyle factors (physical activity, diet, sleep duration, smoking, alcohol consumption) and a combined healthy lifestyle score were assessed as moderators in a sample from UK biobank (n = 153,621). Childhood maltreatment increased the odds of mental-physical comorbidity by 26% less amongst adults who met the UK physical activity guidelines, compared to those who were less active. Regular physical activity also attenuated the association between childhood maltreatment and cardiometabolic disease alone, as did adherence to sleep duration guidelines. Contrary to our hypotheses, there was evidence to suggest that being a non-smoker and consuming less alcohol than the UK guidelines both strengthened the associations between childhood maltreatment mental-physical comorbidity and cardiometabolic disease alone respectively.

To bridge the gap between childhood and late-mid adulthood, the final empirical chapter investigated whether lifestyle factors influenced the link between childhood adversities and psychological distress, obesity, and their comorbidity in early adulthood (mean age: 30 years). Data from the 1970 British Cohort Study (BCS70; n = 16,407) was used to construct a childhood adversities measure, which was examined as a predictor of the highlighted health problems. Six lifestyle factors (physical activity, a Mediterranean diet pattern, calorie intake, sleep duration, alcohol consumption, and smoking) were further assessed as moderators. An increase in each childhood adversity on a cumulative scale elevated the odds of mental-physical comorbidity by 16%, an effect which was stronger than for mental or physical health problems alone. However, there was no evidence that lifestyle factors moderated these associations, underlining lifestyle factors as moderators in the middle-late adulthood sample only.

Childhood adversities were shown to be a robust predictor of mental-physical comorbidity in all studies despite adherence to a healthy lifestyle. Synthesising findings across the three empirical chapters, moderation effects were specific to the UK biobank cohort, which are hypothesised to be due to the cumulative long-term impacts of lifestyle behaviours, increased sample size, or the cohort-specific measurements. Regular physical activity emerged as an attenuating moderator of the link between childhood maltreatment and comorbid depression and cardiometabolic disease in a mid-late adulthood sample, whilst regular physical activity and adequate sleep duration attenuated the increased risk of cardiometabolic disease. These lifestyle behaviours may reduce the negative effects of childhood maltreatment on mid-late adulthood health problems, and their protective qualities which mitigate the elevated risk of mental-physical comorbidity which emerges in early adulthood should be investigated further.

Date of Award	31 Dec 2024
Original language	English
Awarding Institution	University of Bath
Supervisor	Tom Lancaster (Supervisor) & Graeme Fairchild (Supervisor)