A longitudinal study of individuals with major depressive disorder in China found that subjective cognitive dysfunction is strongly linked to the severity of depressive symptoms. Recovery of social functioning in these individuals was influenced by improvements in both depressive symptoms and subjective cognitive function, with subjective cognitive improvements contributing more substantially to recovery. The research was published in Psychological Medicine.
Depression, or major depressive disorder, is a mental health condition marked by persistent sadness and a loss of interest in previously enjoyed activities. It affects how people feel, think, and behave, and can lead to a range of emotional and physical problems. Individuals with depression often have difficulty carrying out daily tasks and may feel hopeless. Common symptoms include fatigue, appetite changes, sleep disturbances, and low motivation or energy.
In addition to emotional symptoms, research indicates that people with depression frequently experience cognitive impairments, such as difficulty concentrating, forgetfulness, trouble making decisions, and slowed thinking. These cognitive issues can continue even after mood symptoms have improved.
Study author Jingjing Zhou and her colleagues set out to explore the relationship between subjective and objective cognitive function and emotional symptoms in people with depression. They also investigated how these symptoms affected social functioning. The researchers hypothesized that cognitive symptoms and emotional symptoms might be at least partly independent and that subjective and objective cognitive difficulties would have different effects on patients’ daily lives.
The study analyzed data from the Prospective Cohort Study of Depression in China (PROUD), a multicenter project designed to recruit a nationally representative sample of people with major depressive disorder. This analysis included data collected between June 2022 and June 2024 from 1,376 patients across 18 hospitals in China. Of these participants, 900 were female, 252 had a family history of mental illness, and 820 were experiencing their first episode of depression. The median age of participants was approximately 28 years.
Patients received antidepressant monotherapy and were followed over an 8-week period, with additional follow-up assessments conducted 52 weeks after the start of treatment. The researchers used several standardized tools to evaluate depressive symptoms (Hamilton Depression Rating Scale and Quick Inventory of Depressive Symptomatology – Self-Report), anxiety (Hamilton Anxiety Rating Scale and Generalized Anxiety Disorder-7), cognitive functioning (Chinese Brief Cognitive Test for objective performance, and the Perceived Deficits Questionnaire – Depression-5 for subjective experience), and social impairment (Sheehan Disability Scale).
The results showed that both depressive symptoms and cognitive functioning improved significantly during the first 8 weeks of treatment. However, subjective cognitive complaints at the beginning of the study predicted the severity of depressive symptoms at week 8, and to a lesser extent, the reverse was also true. This mutual relationship was observed for both depressive and anxiety symptoms.
When the researchers looked at recovery of social functioning, they found it was influenced by both mood improvement and improvements in subjective cognition. However, changes in subjective cognitive function were more strongly associated with social recovery than changes in depression symptoms.
“Subjective cognitive dysfunction is more strongly associated with depressive symptoms and plays a significant role in social functioning recovery, highlighting the need for targeted interventions addressing subjective cognitive deficits in MDD [major depressive disorder],” the study authors concluded.
The study sheds light on the importance of impaired cognitive functioning in depression. However, it should be noted that the design of the study does not allow any definitive causal inferences to be derived from the results.
The paper, “A longitudinal analysis of the relationship between emotional symptoms and cognitive function in patients with major depressive disorder,” was authored by Jingjing Zhou, Jinjie Xu, Zizhao Feng, Rui Liu, Le Xiao, Ruinan Li, Xiaoya Li, Xueshan Zhang, Jing Liu, Yuan Feng, Jia Zhou, and Gang Wang.
