Great variability is evident in the frequency of episode recurrence and duration.
RC has a female preponderance, and occurs with greater frequency premenstrually, at the puerperium and at menopause. There is nearly an equal distribution of L and H alleles in Caucasians. Individuals with COMT LL would be expected to have higher levels of transynaptic catecholamines due to a reduced COMT degradation of norepinephrine and dopamine. These findings indicate that COMT L could represent a modifying gene that predisposes to ultra-ultra or ultradian cycling in patients with bipolar disorder.