A case of seasonal bipolar disorder exacerbated by Cushing's disease

While depression is common in Cushing's syndrome from whatever cause (pituitary, adrenal, or ectopic adrenocorticotropic hormone-secreting tumor or hyperplasia, or exogenous administration of glucocorticoids) and hypercortisolemia is prevalent in major depression, any association between seasonal affective disorder and Cushing's syndrome is unknown. We present a case of seasonal bipolar disorder, gradually worsening for more than 9 years (1985-1994), accompanied by increasing osteoporosis, mild weight gain, and slight truncal obesity in a middle-aged woman. In January 1991, her seasonal affective disorder was successfully treated with light therapy, but in the following year, bipolar mood swings with a seasonal pattern emerged, which were refractory to light therapy and antidepressants but responsive to lithium. In August 1992, she became depressed despite a 1500-mg lithium daily dosage along with light therapy, and, in 1993, a diagnosis of Cushing's disease (Cushing's syndrome as a result of a pituitary adrenocorticotropic hormone-secreting tumor) was made. The pituitary tumor was removed in February 1994, and pituitary function was fully restored by 1996. While the symptoms of Cushing's syndrome subsided, her bipolar illness continued to require maintenance treatment with low doses of lithium but did not require light therapy.