持续性抑郁症的病理生理学机制尚不清楚。DSM-IV-TR 手册中分类讨论了心境恶劣是“轴 II”(“人格”)障碍中的一种疾病,而非“轴 I”(重性精神病)障碍中的疾病(尽管 DSM-5 取消了轴 II 概念,避免了这一差别),对此存在讨论。[20]Klein DN, Riso LP, Donaldson SK, et al. Family study of early-onset dysthymia. Mood and personality disorders in relatives of outpatients with dysthymia and episodic major depression and normal controls. Arch Gen Psychiatry. 1995;52:487-496.http://www.ncbi.nlm.nih.gov/pubmed/7771919?tool=bestpractice.com然而,治疗学研究显示,心境恶劣更类似于轴I心境障碍的其他类型,例如,慢性重性抑郁。[20]Klein DN, Riso LP, Donaldson SK, et al. Family study of early-onset dysthymia. Mood and personality disorders in relatives of outpatients with dysthymia and episodic major depression and normal controls. Arch Gen Psychiatry. 1995;52:487-496.http://www.ncbi.nlm.nih.gov/pubmed/7771919?tool=bestpractice.com[22]Akiskal HS. Dysthymic disorder: psychopathology of proposed chronic depressive subtypes. Am J Psychiatry. 1983;140:11-20.http://www.ncbi.nlm.nih.gov/pubmed/6336637?tool=bestpractice.com[23]Akiskal HS, Rosenthal TL, Haykal RF, et al. Characterological depressions. Clinical and sleep EEG findings separating 'subaffective dysthymias' from 'character spectrum disorders. Arch Gen Psychiatry. 1980;37:777-783.http://www.ncbi.nlm.nih.gov/pubmed/7396655?tool=bestpractice.com
不同类型的慢性抑郁患者出现了五羟色胺和去甲肾上腺素以及多巴胺 (DA) 的变化。