The attenuated response or unresponsiveness was seen in more than a quarter of patients with bipolar disorder following the discontinuation. The attenuated response was found as many as unresponsiveness in reinstitution of lithium. The acquired unresponsiveness was more often in partially responders than in excellent responders. Those who had episode recurrences during the discontinuation were more likely to show reduced responsiveness. Duration of discontinuation seems to be longer in patients who would have unresponsiveness.