15.1 : 抑郁症：概述

Depression is a common mental illness that manifests as major depression, persistent depressive disorder, and bipolar I and II disorders.

It can be characterized by emotional symptoms like persistent sadness, disinterest in activities, low self-esteem, and biological symptoms like decreased cognition decreased appetite, and sleep disturbances.

Neurobiologically, depression is associated with abnormalities in key brain regions, including the prefrontal cortex, amygdala, and hippocampus.

One theory postulates that depression results from a deficiency of monoamine neurotransmitters regulating mood.

Another hypothesis links depression to reduced neurotrophic factors and diminished neurogenesis.

Depression has also been correlated with hormonal imbalances, specifically elevated cortisol levels and thyroid dysregulation.

Further, glutamate neurotransmission abnormalities and disruptions in the hypothalamic-pituitary-adrenal axis are linked to the condition.

Despite these theories, depression remains a complex disorder, necessitating further research to develop more refined intervention strategies.