Major depressive episode

A major depressive episode is a period when a person feels very sad or empty for at least two weeks, affecting their thoughts, feelings, and daily activities. It involves the brain's mood regulation system, which controls emotions and motivation. People may experience persistent sadness, loss of interest in activities they once enjoyed, changes in appetite or sleep, and difficulty concentrating. This condition can also cause physical symptoms like fatigue and aches. It significantly impacts a person's ability to function at work, school, or in relationships, making everyday tasks challenging.

A major depressive episode is characterized by a distinct period of at least two weeks during which there is a depressed mood or anhedonia nearly every day, accompanied by at least five additional symptoms such as changes in appetite, sleep disturbances, psychomotor agitation or retardation, fatigue, feelings of worthlessness or guilt, impaired concentration, and recurrent thoughts of death. The underlying pathology involves dysregulation of monoamine neurotransmitters (serotonin, norepinephrine, dopamine) and altered neuroplasticity in brain regions like the prefrontal cortex and limbic system. It is often triggered by a combination of genetic vulnerability, psychosocial stressors, and neurobiological changes. This episode is a core feature of major depressive disorder and is associated with significant morbidity, increased risk of suicide, and impaired psychosocial functioning.