What is a primary characteristic of Addison's disease?

Addison's disease is primarily characterized by its impact on hormone levels, specifically the insufficient production of hormones from the adrenal glands, such as cortisol and aldosterone. This condition leads to a range of symptoms, including fatigue, weight loss, low blood pressure, and changes in mood due to hormonal imbalances.

Endocrine disorders like Addison's directly affect the body's metabolism, fluid balance, and stress response, which makes hormone regulation a central concern in this disease. The other options do not accurately represent Addison's disease. Although metabolism can be affected due to the lack of glucocorticoids, the disease itself is not primarily centered on metabolic increase. It is not classified as a neurological disorder, nor is it primarily psychiatric, although patients may experience mood disturbances due to hormonal deficiencies. Therefore, the correct answer focuses on the hormonal aspect, which is the fundamental characteristic of Addison's disease.