Importance Being born or raised in more densely populated or deprived areas is associated with increased risk of nonaffective psychosis in adulthood, but few studies to date have examined the role of general cognitive ability in these associations.

Objective To investigate whether lower IQ contributed to the association between population density or deprivation and nonaffective psychosis (mediation) and whether these associations were stronger in people with lower IQ (effect modification).

Design, Setting, and Participants This prospective cohort study evaluated a population-based sample of men born in Sweden from January 1, 1982, to December 31, 1988, and conscripted into military service at 18 years of age. Data were collected from January 1, 1982, to December 31, 2016, and analyzed from May 1 to December 31, 2018.

Exposures Continuous measures of small area-level population density (persons per square kilometer) and socioeconomic deprivation at birth. Deprivation was based on area-level social, criminal, and unemployment data. IQ was assessed during conscription at 18 years of age (mean [SD] IQ, 100 [15]).

Main Outcomes and Measures First diagnosis of International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, nonaffective psychosis from 18 years of age until December 31, 2016, recorded in the National Patient Register.

Results The study sample included a total of 227 429 men who were classified as at risk of psychosis from 18 years of age until the end of follow-up. Of these, 1596 men (0.7%) were diagnosed with nonaffective psychosis. After adjustments for confounders, odds of nonaffective psychosis increased per 1-SD increase in population density (odds ratio [OR], 1.07; 95% CI, 1.04-1.14) and deprivation (OR, 1.09; 95% CI, 1.02-1.13) at birth. IQ was negatively associated with deprivation after adjustments (effect estimate per 1-SD increase in deprivation: −0.70 points; 95% CI, −0.78 to −0.62 points) but not with population density. In mediation analyses, based on the potential outcome framework, 23% (95% CI, 17%-49%) of the total effect of deprivation on nonaffective psychosis was mediated by IQ. IQ did not modify associations between deprivation or population density and nonaffective psychosis.

Conclusions and Relevance These findings suggest that being born in more deprived neighborhoods may partly increase risk of nonaffective psychosis through subsequent effects on cognitive development, consistent with the wider literature on neurodevelopmental delays associated with psychotic disorder. Identifying factors in deprived environments that give rise to this process could inform public health strategies to prevent nonaffective psychosis.

重要性 在人口稠密或贫困的地区出生或成长与成年后非情感性精神病的风险增加有关，但迄今为止，很少有研究检查一般认知能力在这些关联中的作用。

目的 探讨低智商是否有助于人口密度或剥夺与非情感性精神病（调解）之间的关联，以及这些关联在智商较低的人（效果改变）中是否更强。

设计，环境和参与者 这项前瞻性队列研究评估了从1982年1月1日至1988年12月31日在瑞典出生并入伍18岁时服役的男性人群。收集了1982年1月1日至2016年12月31日的数据，并分析了2018年5月1日至12月31日的数据。

暴露 持续测量小面积的人口密度（每平方公里的人数）和出生时的社会经济剥夺。剥夺是基于地区级别的社会，犯罪和失业数据。在征募期间对18岁的智商进行了评估（平均[SD] IQ，100 [15]）。

主要结果和措施 从18岁到2016年12月31日，对《疾病和相关健康问题国际统计学分类》的首次诊断，第十次修订，非情感性精神病，记录在国家患者登记簿中。

结果 该研究样本包括总共227429名从18岁到随访结束被归类为有精神病风险的男性。其中，有1596名男性（占0.7％）被诊断为非情感性精神病。调整混杂因素后，人口密度每增加1个标准差（赔率[OR]，1.07； 95％CI，1.04-1.14）和剥夺（OR，1.09； 95％CI，1.02-1.13），非情感性精神病的几率增加出生时。调整后的智商与剥夺呈负相关（每1-SD剥夺的影响估计值：-0.70点； 95％CI，-0.78至-0.62点），而不与人口密度有关。在调解分析中，基于潜在的结果框架，智商调节了剥夺对非情感性精神病总影响的23％（95％CI，17％-49％）。

结论与相关性 这些发现表明，出生在较贫困的社区可能会通过对认知发育的后续影响而部分增加非情感性精神病的风险，这与有关精神病的神经发育迟缓的广泛文献一致。确定贫困环境中引起这一过程的因素，可以为预防非情感性精神病的公共卫生策略提供依据。