Clinical Features of Patients with Dysthymia in a Large Cohort of Han Chinese Women with Recurrent Major Depression

Wenqing Wu,Runde Pan,Danhua Gu,Yan Wei,Xueyi Wang,Ming Tao,Guibing Chen,Jianhua Shen,Baowei Ha,Guanghua Zhang,Fengyu Yu,Guoqing Jiang,Tieqiao Liu,Xiaohong Hong,Wei Zhang,Ying Liu,Hong Sang,Lijun Yang,Qiyi Mei,Donglin Yang,Qiwen Zhang,Hong Deng,Kenneth S Kendler,Yi Li,Jicheng Dong,Jing Sun,Kerang Zhang,Guodong Miao,Zhoubing Wang,Gongying Li,Wei Liang,Lanfen Liu,Shugui Gao,Zhengrong Liu,Jonathan Flint,Yihan Li,Yiping Chen,Zhenming Shen,Kan Li,Bo Du,Xiaojuan Liu,Zhen Zhang,Hui Zhong,Jinbei Zhang,Yunchun Chen,Yan Song,Chengge Gao,Xiaoping Wang,Xiang Fang,Jiyang Pan,Guoping Huang,Jingfang Gao,Huaqing Meng,Youhui Li,Gang Wang,Yutang Zhang,Min Cai,Jiannong Shi ,Wei Wu ,Jianguo Hu ,Sheng Shi ,Tiebang Liu,Chunmei Hu,Xumei Wang

doi:10.1371/journal.pone.0083490

Abstract

BackgroundDysthymia is a form of chronic mild depression that has a complex relationship with major depressive disorder (MDD). Here we investigate the role of environmental risk factors, including stressful life events and parenting style, in patients with both MDD and dysthymia. We ask whether these risk factors act in the same way in MDD with and without dysthymia.ResultsWe examined the clinical features in 5,950 Han Chinese women with MDD between 30–60 years of age across China. We confirmed earlier results by replicating prior analyses in 3,950 new MDD cases. There were no significant differences between the two data sets. We identified sixteen stressful life events that significantly increase the risk of dysthymia, given the presence of MDD. Low parental warmth, from either mother or father, increases the risk of dysthymia. Highly threatening but short-lived threats (such as rape) are more specific for MDD than dysthymia. While for MDD more severe life events show the largest odds ratio versus controls, this was not seen for cases of MDD with or without dysthymia.ConclusionsThere are increased rates of stressful life events in MDD with dysthymia, but the impact of life events on susceptibility to dysthymia with MDD differs from that seen for MDD alone. The pattern does not fit a simple dose-response relationship, suggesting that there are moderating factors involved in the relationship between environmental precipitants and the onset of dysthymia. It is possible that severe life events in childhood events index a general susceptibility to chronic depression, rather than acting specifically as risk factors for dysthymia.

Highlights

Dysthymia is a form of chronic depression characterized by depressed mood and symptoms lasting two years or more [1,2,3,4]
Chronic uncontrollable stressful life events may be as important in the aetiology of dysthymia as they are for major depressive disorder (MDD)
In this paper we address the issue of the relationship between risk factors for MDD and dysthymia as part of the China, Oxford and VCU Experimental Research on Genetic Epidemiology (CONVERGE) study of MDD

Summary

Introduction

Dysthymia is a form of chronic depression characterized by depressed mood and symptoms lasting two years or more [1,2,3,4]. Dysthymic patients tend to have a fluctuating course [5] and often have a superimposed episode of major depressive disorder (MDD). While some studies show that stressful life events are not a consistent predictor of chronicity in depression [17], it is possible that specific types of stressful life event may more frequently precede the onset of dysthymia than MDD [18,19]. Given that almost all patients with dysthymia develop at least one episode of MDD[9], this comparison is likely to yield useful information about the relative importance of life events in the two disorders. We investigate the role of environmental risk factors, including stressful life events and parenting style, in patients with both MDD and dysthymia. We ask whether these risk factors act in the same way in MDD with and without dysthymia

Methods

Results

Discussion

Conclusion