Does Population Density and Neighborhood Deprivation Predict Schizophrenia? A Nationwide Swedish Family-Based Study of 2.4 Million Individuals

Abstract

People living in densely populated and socially disorganized areas have higher rates of psychiatric morbidity, but the potential causal status of such factors is uncertain. We used nationwide Swedish longitudinal registry data to identify all children born 1967–1989 (n = 2 361 585), including separate datasets for all cousins (n = 1 715 059) and siblings (n = 1 667 894). The nature of the associations between population density and neighborhood deprivation and individual risk for a schizophrenia diagnosis was investigated while adjusting for unobserved familial risk factors (through cousin and sibling comparisons) and then compared with similar associations for depression. We generated familial pedigree structures using the Multi-Generation Registry and identified study participants with schizophrenia and depression using the National Patient Registry. Fixed-effects logistic regression models were used to study within-family estimates. Population density, measured as ln(population size/km2), at age 15 predicted subsequent schizophrenia in the population (OR = 1.10; 95% CI: 1.09; 1.11). Unobserved familial risk factors shared by cousins within extended families attenuated the association (1.06; 1.03; 1.10), and the link disappeared entirely within nuclear families (1.02; 0.97; 1.08). Similar results were found for neighborhood deprivation as predictor and for depression as outcome. Sensitivity tests demonstrated that timing and accumulation effects of the exposures (mean scores across birth, ages 1–5, 6–10, and 11–15 years) did not alter the findings. Excess risks of psychiatric morbidity, particularly schizophrenia, in densely populated and socioeconomically deprived Swedish neighborhoods appear, therefore, to result primarily from unobserved familial selection factors. Previous studies may have overemphasized the etiological importance of these environmental factors.

Validity and reliability of chronic tic disorder and obsessive-compulsive disorder diagnoses in the Swedish National Patient Register

“…A large variety of epidemiological and genetic studies of psychiatric disorders, including OCD, have been based on the NPR. [6][7][8][9][10][11][12] Strengths of such register-based studies include the very large, unselected sample sizes, resulting in high statistical power and minimising the risk of ascertainment biases, the possibility of examining risk factors prospectively and the possibility of reconstructing large family pedigrees.…”

The association between childhood relocations and subsequent risk of suicide attempt, psychiatric problems, and low academic achievement

“…Second, we were unable to explore moderating factors, such as the motive behind relocating (e.g., if relocation is due to a “crisis,” the effect may be more detrimental) (Tucker et al , 1998), or the population density and neighborhood deprivation of the post-relocation area (Pedersen and Mortensen, 2001). Despite this, previous research has demonstrated that the association between relocations to more dense or deprived neighborhoods and schizophrenia, for example, is negligible when controlling for unmeasured familial risk factors shared by cousins and siblings (Sariaslan et al , 2014). Third, the results are based solely on Swedish data, which may not generalize to other countries or cultures.…”

Environmental chemicals mediated the effect of old housing on adult health problems: US NHANES, 2009–2010

“…On the other hand, there has also been growing evidence showing that social and psychological environments could have stronger effects on human health rather than urbanisation levels (Sariaslan et al 2014;Shiue 2012). Therefore, the role of urbanisation level could be minimal.…”