What is a common physiological change associated with major depression?

The correct answer highlights that decreased serotonin production is commonly associated with major depression. Serotonin is a neurotransmitter that plays a crucial role in mood regulation. In individuals suffering from major depression, research shows that there is often a decrease in serotonin levels or serotonin function, which can contribute to the persistence of depressive symptoms. This understanding is foundational in both diagnosing and treating depression, often leading to the use of selective serotonin reuptake inhibitors (SSRIs) that aim to increase serotonin levels in the brain.

The other choices reference concepts that are less commonly or inaccurately associated with major depression. Increased activity in the right prefrontal cortex is often linked to negative emotions and could be a response to depression but is not a direct physiological change typically emphasized. Stable cortisol levels do not apply, as individuals with major depression frequently exhibit altered cortisol levels due to the stress response, often leading to increased levels. Increased dopamine activity is generally not associated with major depression; in fact, lower dopamine activity is often observed, particularly in relation to motivation and reward processing. These distinctions are important to understand the neurobiological underpinnings of major depression.