Data were collected on all people born in Denmark from 1971 to 1997 documenting every residential childhood move from birth to 14 years. Each move was associated with the age of the child so that the impact of early-in-life moves could be contrasted with moves during the early teenage years. With a number of comprehensive national registries at their disposal, the team of researchers was able to measure and correlate subsequent negative events in adulthood, including attempted suicide, violent criminality, psychiatric illness, substance misuse, and natural and unnatural deaths.
“Owing to its uniquely complete and accurate registration of all residential changes in its population, Denmark is the only country where it is currently possible to conduct such a comprehensive national investigation of childhood residential mobility and risk of adverse outcomes in later life,” explained lead investigator Roger T. Webb, PhD, Centre for Mental Health and Safety, University of Manchester (UK).
The risk of adverse outcomes due to residential mobility during childhood was classified into three categories: self-directed and interpersonal violence: (attempted suicide, violent criminality), mental illness and substance misuse (any psychiatric diagnosis, substance misuse), and premature mortality (natural and unnatural deaths).
Thirty-seven percent of people studied relocated across a municipal boundary at least once before reaching their 15th birthdays, with multiple relocations occurring most frequently during infancy. Across all adverse outcomes studied, the highest risks were among individuals who moved frequently during early adolescence.
Statistical analysis was particularly robust. “Dose-response” relationships were evident for every outcome category and each additional move was associated with an incremental risk increase. For example, data analysis showed that risk increased with multiple moves at any age versus a single move, and that an even sharper spike in risk for violent offending was observed with multiple relocations within a single year. The attempted suicide risk increased steadily with rising age at the time of the move, and was markedly raised if multiple annual relocations occurred during early adolescence (12-14 years of age).
Socioeconomic status (SES) of the families was determined by looking at: income (annual quintiles), highest educational attainment level (primary school, high school/vocational training, higher education), and employment status (employed, unemployed, outside workforce for other reasons). Lower SES was assigned when both parents scored low in at least one of the three areas. Higher SES required both parents to be employed and a high score in income or education. Middle SES encompassed all other combinations.
Interestingly the initial hypothesis that adverse outcomes might be more prevalent in households with lower SES was not borne out by this study, where markedly elevated risk due to residential moves during early/mid adolescence applied to all SES levels.
According to Dr. Webb, “Childhood residential mobility is associated with multiple long-term adverse outcomes. Although frequent residential mobility could be a marker for familial psychosocial difficulties, the elevated risks were observed across the socioeconomic spectrum, and mobility may be intrinsically harmful. Health and social services, schools, and other public agencies should be vigilant of the psychological needs of relocated adolescents, including those from affluent as well as deprived families.”