A nurse is discussing the theories that explain the biological basis of Major Depressive Disorder (MDD) with a group of nursing students. Which theory suggests that depression is caused by an imbalance of neurotransmitters in the brain that regulate mood, motivation, reward, cognition, and stress response?

Choice A rationale:

Bipolar disorder involves both depressive episodes and manic episodes. The client in question denies any history of manic episodes, making bipolar disorder less likely as a diagnosis. Manic episodes are characterized by elevated mood, increased energy, impulsivity, and risky behavior.

Choice B rationale:

Dysthymia, also known as persistent depressive disorder, involves chronic feelings of sadness and a lack of interest or pleasure in activities. It is a milder form of depression that persists for at least two years in adults. The client's persistent feelings of sadness align more closely with the criteria for dysthymia.

Choice C rationale:

Substance-induced mood disorder occurs when the client's mood disturbances are a direct result of substance use or withdrawal. Since there is no mention of substance use or withdrawal in the client's history, this choice is less relevant to the scenario.

Choice D rationale:

Adjustment disorder is characterized by the development of emotional or behavioral symptoms in response to an identifiable stressor, and these symptoms typically resolve within six months of the stressor's resolution. In the scenario, there is no indication of a recent stressor, and the client's symptoms seem to be chronic rather than time-limited, making adjustment disorder less likely.

Choice A rationale:

"MDD is less severe than dysthymia but lasts for at least 2 years." This statement is incorrect. Major Depressive Disorder (MDD) is characterized by the presence of a major depressive episode, which can be severe and persistent, lasting for at least two weeks. Dysthymia, on the other hand, is a chronic but milder form of depression that lasts for at least two years, not MDD.

Choice B rationale:

"Dysthymia is characterized by alternating episodes of mania and depression." This statement is incorrect. Dysthymia is a chronic mood disorder characterized by a persistent low mood and other depressive symptoms. It does not involve alternating episodes of mania and depression. Alternating episodes of mania and depression are characteristic of bipolar disorder, not dysthymia.

Choice C rationale:

"Unlike MDD, dysthymia does not impair social or occupational functioning." This statement is incorrect. Both Major Depressive Disorder (MDD) and dysthymia can significantly impair social, occupational, and other areas of functioning. In fact, dysthymia's chronic nature often leads to long-term impairment in various aspects of an individual's life, similar to MDD.

Choice D rationale:

"Dysthymia is chronic and lasts for at least 2 years, but is less severe than MDD." This statement is accurate. Dysthymia is a chronic form of depression that persists for at least two years. While it may not exhibit the same level of severity as a major depressive episode, its long-term nature can still have a substantial impact on an individual's quality of life. This distinguishes it from MDD, which can have episodic occurrences.