The daily patterns of depression: How symptoms tend to co-occur over time

A daily diary study examining the relationships between different symptoms of depression found that higher levels of sleep disturbance, sad mood, and concentration difficulties predicted higher levels of multiple different symptoms on the following day. Individuals with higher levels of anhedonia, anxiety, and concentration difficulties tended to experience a broader range of depression symptoms. The paper was published in the British Journal of Psychology.

Depression is a mental health condition characterized by persistent low mood or loss of interest and pleasure that interferes with everyday functioning. It is different from ordinary sadness because the symptoms typically persist for most of the day, nearly every day, for at least two weeks. A person with depression may feel sad, empty, hopeless, or unusually irritable. They may lose interest in activities they previously enjoyed and withdraw from other people.

Depression can cause a wide range of different symptoms. For example, common symptoms include fatigue, low energy, reduced motivation, and difficulty completing routine tasks. Cognitive symptoms include poor concentration, indecisiveness, slower thinking, and problems with memory. Physical and behavioral symptoms include disturbed sleep, changes in appetite or body weight, and either restlessness or unusually slowed movement and speech. Some people experience feelings of worthlessness, excessive guilt, or pessimism about the future. In more severe cases, depression may involve thoughts of death, self-harm, or suicide.

Study author Meghan E. Quinn and her colleagues conducted a study to identify patterns of co-occurrence of depressive symptoms. They wanted to better understand how symptoms of depression occur in relation to each other. In particular, they wanted to identify symptoms that predict and potentially cause each other from day to day, and symptoms that tend to co-occur within the same day or across the entire month.

Study participants were 363 undergraduate students. The participants’ average age was 19 years. Sixty-one percent of them were women. They were recruited from an undergraduate research pool at the College of William & Mary, a university in the eastern United States, and received course credit in exchange for their participation.

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At the start of the study, participants provided demographic data and completed an assessment of depressive symptom severity. After this, they started a 28-day daily diary portion of the study, during which they received a brief survey about depressive symptoms every day. Each day at 7 a.m., participants received the survey and were asked to respond based on how they were feeling the previous day.

On average, participants completed 82% of the 28 daily diaries. Based on baseline assessments, 43% of participants were characterized as non-depressed, 31% as having minimal depression, and 26% as suffering from mild to severe depression. The most commonly reported symptoms across the 28 days were anxiety, followed by concentration difficulties or indecision, sleep disturbance, fatigue, and psychomotor symptoms. Suicidal ideation was the rarest.

Analyses of the relationships between symptoms revealed that higher levels of sleep disturbance, sad mood, and concentration difficulties on a given day predicted higher levels of multiple different symptoms on the following day. When looking at symptoms occurring on the exact same day, sad mood, anhedonia (the inability to feel pleasure), and fatigue tended to co-occur with many other symptoms.

When comparing different participants across the entire month-long period, the results showed that individuals with higher average levels of anhedonia, anxiety, sad mood, and concentration difficulties tended to experience a broader range of depressive symptoms overall.

“These findings underscore the complexity of depressive symptom interactions and highlight potential ways in which depression may manifest. Future research should explore the identified relations to clarify causal relations among symptoms as well as trait-level vulnerability to symptoms,” the study authors concluded.

The study contributes to the scientific knowledge about depression. However, it should be noted that the study participants were undergraduate students, most of whom were not depressed or showed minimal depression symptoms. Findings on other demographic or age groups, or on patients diagnosed with major depressive disorder, might differ.

The paper, “Relations among daily symptoms of depression,” was authored by Meghan E. Quinn, Mary E. Kleinman, John P. Standring, and Qimin Liu.