Rural-urban migration patterns and mental health diagnoses of adolescents and young adults in British Columbia, Canada: a case-control study

Considerable theoretical debate has focused on the relationships between the development of mental health problems among youth and the role played by environmental stressors such as acute traumatic events, chronic strain and adversity, accumulation of stressful life events, and daily challenges [1–4]. The most notable factors known to have a profound impact on youth mental health include exposure to neighborhood violence [5]; parental chronic illness [6, 7], and poverty and economic hardship [8]; as well as parental unemployment, which may add further stress in the form of increased parental alcohol intake, home violence, and child abuse [9].

Much evidence shows that several of these stressors may vary according to where individuals live. That is, the economy and social environment of the communities where youth live may be associated with the degree to which parents are able to find jobs, rely on the necessary networks of social support to cope with challenging times, and provide their children with opportunities for healthy development (for comprehensive reviews, see [10, 11]). Since the extent to which these stressors are present may differ between rural versus urban communities, we explore whether exposure to urban or rural environments places youth and young adults at greater risk for poor mental health outcomes.

This study is based on a cohort of male sawmill workers (N = 28,794) on whom data was first gathered in the mid-1990s to study the effects of chlorophenol antisapstain exposure among British Columbian sawmill workers [34]. Recently, the original study cohort has been extended to investigate the association between job history, work stress, and health outcomes among the cohort participants and their children [35–37]. For the present study, personnel records for workers who had worked in one of 14 sawmills for at least one year between 1950 and 1998 were accessed and compiled. The birth files from the British Columbia provincial vital statistics registry were used to identify the children of the sawmill workers who were born between 1952 and 2000. Probabilistic linkage techniques were used to identify the study participants and their mental health diagnoses. More specifically, to link records of the children to those of the fathers, we used the Medical Services Plan (MSP) number (the equivalent to a health personal number), gender of the child, date of birth, surname, and given names. This probabilistic technique yielded a success rate of 87%. A total of 37,827 children of sawmill workers were identified, forming an offspring cohort that includes individuals of varying age, ranging from young children to adults.

Mental health information of children of sawmill workers was gathered from the provincial administrative health data. The Canadian health system is public and universally accessible and it is regulated at the provincial level. In British Columbia, individuals experiencing mental health problems can be evaluated by mental health professionals at public hospitals or medical clinics. Every encounter that occurs between patients and health professionals is recorded on administrative forms that are sent and stored at the British Columbia Ministry of Health. The reason for medical visit or hospitalization (which can include a diagnosis if one is provided), and personal health information are recorded on such forms. This individual-level administrative health information is available to researchers who have obtained approval as the result of a stringent process of review of ethical standards and scientific rigor. Such data, which also include codes for mental health diagnoses in accordance with international code systems, are accessed at the British Columbia Linked Health Database (BCLHDB). Ethical approval was obtained from the University of British Columbia (UBC) and the British Columbia Ministry of Health to conduct a series of studies on the health of sawmill workers and their children.

Odds ratio (OR) analyses revealed that after controlling for important paternal characteristics, rural stability is significantly associated with acute reaction to stress and depression. Specifically, individuals who were born in and grew up in the same rural community were approximately 25% less likely to be diagnosed with acute reaction to stress (OR = 0.740; p = .004; 95%CI = .602-.910) and approximately 10% less likely to be diagnosed with depression (OR = 0.881; p = .044; 95%CI = .780-.996) than those who had not grown up in the same rural community in which they were born. Similarly, individuals who had migrated between rural communities were approximately 50% less likely to be diagnosed with adjustment reaction (OR = 0.571; p < .001; 95%CI = .441-.739) than participants who stayed in the rural communities in which they were born. Interestingly, nondependent drug abuse was not significantly associated with rural stability (OR = 0.935; p > .05; 95%CI = .627-1.39) or migration between rural communities (OR = 1.42; p > .05; 95%CI = .952-2.11).

The present findings show that growing up in a rural environment or migrating between rural communities may protect against some mental health conditions, namely, acute reaction to stress, adjustment reaction, and depression. More specifically, youth and adults who grew up in the same rural community were at lower risk of being diagnosed with depression and adjustment reaction than individuals who did not grow up in the same rural community in which they were born, and children migrating between rural communities were at lower risk of being diagnosed with acute reaction to stress than participants who did not migrate between rural communities.

However, it is worth noting that for other mental health diagnoses we did not find a link with migration patterns. For example, we did not find significant differences between rural and urban environments or migration patterns between these two types of environments in the diagnosis of neurotic disorder, personality disorder, alcohol dependence, and nondependent drug abuse. Therefore we conclude that if rurality plays a protective role in the development of mental health, it does so only for specific conditions.

We argue that clues to what might be protecting children living in rural communities from developing acute reactions to stress, adjustment reaction, or depression may be suggested by a null finding. We found that, after controlling for important paternal sociodemographic characteristics, adolescents and young adults living in rural places are as likely to become nondependent drug abusers as individuals growing up in urban communities. We qualify this null finding as important because it is indeed consistent with our interpretation of the protective role of rurality. However, it is contrary to a literature showing that leisure boredom is associated with substance abuse [e.g., [28, 39–41]], especially among rural youth [42–46], and suggesting that there may be some characteristics of rurality that put youth at risk for drug abuse.

It has been speculated that some of the alleged risk factors of rurality may be linked to the remoteness, isolation, and seclusion that generally are embedded in rural living and attract rural youth to large cities. Paradoxically, these features may relate to a perceived sense of status quo and lack of change. The underlying rationale is that the association between boredom and drug use in adolescents and young adults might be stronger in rural than in urban communities because living in rural communities might make individuals within these developmental periods more prone to boredom and, by implication, might make them experience less change or novelty than their counterparts living in urban communities.

Our analyses clearly show that, when individuals are matched for a series of family and socioeconomic variables, differences relative to nondependent drug abuse among rural and urban groups disappear. Thus, we conclude that it is possible that the differences found in relation to nondependent drug abuse reported in the literature may be due to the fact that the latent variable boredom may be confounded with uncontrolled socioeconomic and family variables, which instead reflect the typically greater availability of resources and access to services, facilities, and amenities enjoyed by urban populations.

Indeed, the pattern of results in our study suggests an alternative interpretation of the influence of rurality. That is, keeping constant the extent of access and resources varying with living contexts, rurality may well play a protective role for mental health of adolescents and young adults because it provides them with a needed sense of stability and control.

This proposed interpretation evokes a host of interesting questions concerning what is the optimal level of "social environment stimulation" in critical periods such as adolescence and young adulthood. Research addressing such questions has almost exclusively focused on infancy and early childhood, but seems to have largely neglected other developmental periods in the life span, and to have underestimated the role played by the context in which individuals live. Clearly, given the potential important links with lifestyle, well-being, and health outcomes, this should be an area of priority for future research.

While approaches to health policy tend to treat rural areas as uniform entities, mental health differences between rural areas may be as pronounced as those observed between urban and rural communities. There are an array of different and specific dimensions of rurality and urbanity that health researchers need to consider to better understand what community aspects may be associated with mental health outcomes [47]. For example, resource-dependent rural communities can be extremely different from one another, because farming, mining, and forestry are each affected differently by shifts in the market economy and availability of resources. Such shifts may also be partially responsible for individual trends in migration, which in turn represent an important element of the community social fabric. At the same time, the influences of rurality cannot be studied without controlling for individual-level characteristics that contribute to the socioeconomic profile of an entire community.

The present study has highlighted the important role played by stability, as opposed to migration, in contributing to the mental health of members of rural and urban communities. Our findings also suggest that important family characteristics such as sociodemographics, duration of employment, and a history of mental health may be possible confounders in previous studies in which differences between rural and urban communities have been identified.

While in this study we treated paternal characteristics (e.g., mental health diagnosis, work history, and ethnicity) as control variables, it is worth noting that these were consistently associated with increased risk of mental health diagnosis among the children. More specifically, paternal mental health diagnosis and Caucasian origins (compared to Chinese and Sikh) were associated with greater odds of mental health diagnosis among the children. These findings may explain in part some of the inconsistencies between rural and urban communities in drug use reported in the literature, as the inconsistent results could be confounded by factors such as ethnicity and familial history of mental health.

There are a number of limitations to this study that are worth mentioning. First, because our outcome measures were derived from medical records, we were not able to address the link between mental health and urbanity-rurality that may exist at the subclinical level, nor could we explore the role of potentially important contextual factors (e.g., social capital). Second, while we controlled for important sociodemographic and mental health characteristics of the fathers, we did not have access to maternal characteristics and therefore could not include them in this study. Third, the participants in the study represent a very specific population - that is, the children of male sawmill workers in British Columbia, Canada - and therefore findings from this study cannot be generalized. Finally, rural health researchers may be critical of our definition of rurality, which was solely based on population size (centers with less than 100,000 people), and our classification of migration patterns is reductive in that it did not divide urban migrators into those who migrated to other urban places and those who migrated from urban to rural places.

Because of the limitations of this study, further research on this topic needs to be conducted before recommendations for clinical practice can be extrapolated. Nonetheless, it is reasonable to advocate for a clinical practice that takes into consideration not only the individual histories of patients, but also the influence that broader social environments exert on the etiology of mental health conditions. This is a critical concept since it may have implications for treatment of the individual, but also for the identification of large-scale public mental health prevention programs.

Thanks to the use of a relatively homogeneous sample, this study provides some compelling evidence of the protective role of rural environments in the development of some mental health conditions (i.e., depression, adjustment reaction, and acute reaction to stress) but not others (e.g., nondependent drug abuse).