Seasonal affective disorder (SAD) famously follows annual cycles, with incidence elevation in the fall and spring. Should some version of cyclic annual pattern be expected from other psychiatric disorders? Would annual cycles be similar for distinct psychiatric conditions? This study probes these questions using 2 very large datasets describing the health histories of 150 million unique U.S. citizens and the entire Swedish population. We performed 2 types of analysis, using "uncorrected" and "corrected" observations. The former analysis focused on counts of daily patient visits associated with each disease. The latter analysis instead looked at the proportion of disease-specific visits within the total volume of visits for a time interval. In the uncorrected analysis, we found that psychiatric disorders' annual patterns were remarkably similar across the studied diseases in both countries, with the magnitude of annual variation significantly higher in Sweden than in the United States for psychiatric, but not infectious diseases. In the corrected analysis, only 1 group of patients-11 to 20 years old-reproduced all regularities we observed for psychiatric disorders in the uncorrected analysis; the annual healthcare-seeking visit patterns associated with other age-groups changed drastically. Analogous analyses over infectious diseases were less divergent over these 2 types of computation. Comparing these 2 sets of results in the context of published psychiatric disorder seasonality studies, we tend to believe that our uncorrected results are more likely to capture the real trends, while the corrected results perhaps reflect mostly artifacts determined by dominantly fluctuating, health-seeking visits across a given year. However, the divergent results are ultimately inconclusive; thus, we present both sets of results unredacted, and, in the spirit of full disclosure, leave the verdict to the reader.

中文翻译：

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精神疾病是否遵循年度周期性季节性？

众所周知，季节性情感障碍 (SAD) 遵循年度周期，秋季和春季发病率升高。是否应该从其他精神疾病中预期某种版本的周期性年度模式？不同精神疾病的年周期是否相似？本研究使用 2 个非常大的数据集来探讨这些问题，这些数据集描述了 1.5 亿独特的美国公民和整个瑞典人口的健康史。我们使用“未校正”和“校正”观察进行了两种类型的分析。之前的分析侧重于与每种疾病相关的每日患者就诊次数。相反，后一种分析着眼于特定时间段内特定疾病就诊量在总就诊量中的比例。在未经修正的分析中，我们发现精神障碍 两国所研究疾病的年度模式非常相似，瑞典的年度变化幅度明显高于美国的精神疾病，但不是传染病。在校正分析中，只有 11 至 20 岁的一组患者重现了我们在未校正分析中观察到的精神障碍的所有规律；与其他年龄组相关的年度寻求医疗保健的访问模式发生了巨大变化。对传染病的类似分析在这两种计算类型上的分歧较小。在已发表的精神疾病季节性研究的背景下比较这两组结果，我们倾向于相信我们未经校正的结果更有可能捕捉到真实的趋势，而更正后的结果可能主要反映了由特定年份的显着波动、寻求健康的访问所决定的伪影。然而，不同的结果最终没有定论。因此，我们提供未经编辑的两组结果，并本着全面公开的精神，将结论留给读者。