Depressive symptoms

Depressive symptoms are clinical manifestations of depression that can occur with or without a formal diagnosis of major depressive disorder or bipolar disorder. They include depressed mood and anhedonia, which have been described as core symptoms, as well as changes involving sleep, psychomotor function, self-esteem, anxiety, and daily functioning. Symptoms may be measured continuously using instruments such as the Center for Epidemiologic Studies Depression Scale, the Beck Depression Inventory, and the Beck Depression Inventory-II, allowing investigators to characterize the severity and breadth of depressive experiences beyond categorical diagnoses.

Depressive symptoms are studied across diverse medical conditions, including cancer, HIV, fibromyalgia, neurocognitive disorders, Parkinson’s disease, and age-related brain changes. They are evaluated in relation to quality of life, physical activity, activities of daily living, cognitive and functional performance, readmission, mortality, and neuroimaging or serum markers. Current research examines interventions including internet-based emotion regulation, psychomotor therapy, melatonin, digital cognitive behavioural therapy for insomnia, and exercise; however, the available contexts do not establish a single biological mechanism or treatment pathway.