More than PMS ...

Premenstrual mood shifts are associated with depressive symptoms and  bipolar disorder, according to a new study.

The study from Massachusetts General Hospital, which followed almost 300 women, finds premenstrual mood disturbances may serve as a clinical marker predicting more severe bipolar disorder among reproductive-aged women.

Compared to bipolar women without premenstrual mood changes, those with premenstrual mood shifts had more episodes of depression and worse symptoms the following year.

Estrogen and reproductive hormones influence mood through their action on the central nervous system. The way fluctuating hormones influence mood may produce greater mood instability in bipolar women, according to researchers.

Study author Dr. Rodrigo Dias said the study underscores the importance of identifying mood disorders across the menstrual cycle in bipolar patients, who could benefit from more intensive monitoring.

Bipolar disorder is characterized by extreme shifts in mood, ranging from manic highs to crushing lows, and affects about 5.7 million American adults.