Childhood aggression directly and positively predicted overall use of health services in adulthood for the participants of this study, as well as the number of visits they made to specialists, emergency departments and dentists, the number of times they were admitted to hospital, and the number of medical visits they made due to lifestyle-related illnesses and injuries. These associations were seen even when controlling for the effects of sex, education and neighbourhood poverty.
Among young women, childhood aggression increased the use of gynecologic services. This result is consistent with previous research suggesting that agression is related to high-risk sexual behaviour early in life.9,10
Our results suggest that childhood aggression has lasting effects on physical health and can have an impact on the level of use of medical services over many years. Among the participants of our study, childhood aggression did not indiscriminately increase the number of visits to doctors, nor was it associated with an increase in infections. This finding suggests that childhood aggression puts people at risk for specific types of health problems during adulthood that cause them to use medical services more frequently. Our study begins to explore how the use of specific medical services are associated with distinct behaviours.
Among our participants, childhood likeability negatively predicted overall use of medical services, number of medical visits due to injuries and number of government-funded dental visits. The direction of these effects is consistent with research suggesting that adults with larger social networks seem to have better health outcomes than those who are less socially connected.16,17
These data could also suggest that the children who were judged as more likeable by their peers were less likely to engage in risk-taking or impulsive behaviours that could lead to injuries, and more likely to take better care of their overall health. Good social relationships may also offer support and protect against the negative effects of stress, which could aid in the prevention of illness.
Childhood social withdrawal positively predicted the use of government-funded dental services. Though the mechanism underlying this relationship is ambiguous, it could be related to socioeconomic status. Alternatively, shyness and reluctance to seek regular dental care might result in a higher number of emergency dental procedures.
Level of education negatively predicted our participants’ overall use of medical services, visits to emergency departments, admissions to hospital, government-funded dental visits and medical visits due to injuries. These results suggest that people with a higher level of education were less likely than those with less education to need or seek medical attention for these types of problems.
There are several possible explanations for the links seen between education and health. Leaving school prematurely may result in less education about health, which could lead to poor decision-making based on a lack of knowledge. In addition, the jobs available to people who have not finished high school often involve manual labour, which could carry an increased risk of injury. Furthermore, the stress of earning a low income associated with a lower level of education could lead to stress-related illnesses. Finally, deficits in executive functioning and impulse control may underlie both leaving school prematurely and poor adult health by exposing a person to a greater number of high-risk situations in which injury is possible and medical help is necessary.
The level of poverty of the neighbourhood in which participants lived and attended school during their late adolescence and early adulthood predicted the number of visits to specialists, emergency departments and dentists. This variable can be considered as a proxy for socioeconomic status; thus, these results are consistent with previous reports suggesting problems with primary health care among people with low incomes. For example, rates of admissions to hospital and visits to emergency departments have been shown to have a strong sociodemographic component;18
this association has been seen in Canada, where health care is universally accessible.19
Some of the variance in adult health and use of health services could be predicted from the childhood behaviour shown by the participants of this study. This finding is particularly important for primary prevention campaigns aimed at improving public health and decreasing the use of medical services and their associated costs to society. Even modest increases in the use of services in adulthood that can be predicted from childhood variables could amount to huge costs to society when multiplied over millions of people. Knowing how to target those children and adolescents most at risk for poor health later in life could help prevent certain negative health outcomes later in life, as well as potentially decrease health care costs for the Canadian public. Such a strategy requires further study.
Strengths and limitations
Longitudinal designs use a prospective approach rather than rely on retrospective data, which is subject to recall bias. Causal inferences can be drawn more credibly in prospective longitudinal studies because of the establishment of time sequencing in the prediction of outcomes. However, in most cases, conclusions remain speculative as a function of the method, which is correlational. The replication of results across studies, using different samples, is a necessary step in confirming the generality of longitudinal results.20
The effect sizes we saw were modest. However, considering that the childhood variables were collected almost 30 years before the medical data were retrieved, our results offer some insight into the long-term outcomes of childhood aggression and suggest possible avenues for preventive intervention.
Our results confirm that there are specific behavioural characteristics, identifiable in childhood, that can have enduring consequences to physical health and can predict increased use of health services in adulthood. Childhood aggression should be considered a health risk when designing interventions to improve public health, particularly those targeting children and families. To help people at risk, we should address multiple sources of risk. As such, a developmental approach to the prevention and treatment of these problems should be taken. Whether risk factors for poor health in later life can be addressed most effectively in adolescence and early adulthood or whether they should be the focus of earlier preventive interventions in childhood is an issue that needs to be addressed both empirically and from a social policy perspective. Adopting a life-long approach to teaching children, teenagers and young adults appropriate self-care and age-appropriate ways of managing their stress and impulses may effectively prevent poor health outcomes later in life.
We measured our participants’ use of medical services during their early to middle adulthoods. How their health may fare later in life, when lifestyle-related illnesses such as high blood pressure, high cholesterol and coronary artery disease develop remains to be seen. Future research involving this population will help elucidate the lifelong processes of aggression, stressful life circumstances, cognitive and coping strategies, physical health consequences and use of medical services.
Our results add to the literature that suggests the people at greatest risk of poor health in adulthood, as characterized by multiple negative predictors of long-term outcome, might be identified in early childhood. Addressing problematic childhood behaviour and teaching appropriate ways of interacting, self-care and coping strategies to vulnerable children will probably require early preventive intervention to mitigate long-term risks to health.