A nurse is reviewing the medical record of a newly admitted client who has major depressive disorder. Which of the following findings should the nurse identify as a risk factor for this condition?

Choice A reason: Serotonin deficiency is a well-known risk factor for major depressive disorder. Serotonin is a neurotransmitter that plays a crucial role in mood regulation, and its deficiency can lead to symptoms of depression. This is why many antidepressant medications, such as selective serotonin reuptake inhibitors (SSRIs), aim to increase serotonin levels in the brain. Choice B reason: Acute bronchitis is a respiratory condition that involves inflammation of the bronchial tubes. While it can cause significant discomfort and health issues, it is not directly linked to major depressive disorder. However, chronic illnesses can sometimes contribute to depressive symptoms due to the ongoing stress and physical limitations they impose. Choice C reason: Elevated calcium levels, or hypercalcemia, can cause a variety of symptoms, including fatigue, confusion, and depression-like symptoms. However, it is not a primary risk factor for major depressive disorder. Hypercalcemia is usually related to other underlying conditions such as hyperparathyroidism or certain cancers. Choice D reason: Being an only child is not considered a risk factor for major depressive disorder. While family dynamics and social relationships can influence mental health, there is no direct evidence linking being an only child to an increased risk of developing major depressive disorder.