Which of the following statements is true of the chemical abnormalities in the bodies of people who suffer from bipolar disorder? a deficiency in the neurotransmitters dopamine and neuropeptide y (npy) leads to bipolar disorder in people who have experienced stressful situa­tions. high serotonin may be coupled with low levels of norepinephrine in the manic phase and with high levels in the depressed phase. in both the manic and depressed phases, serotonin levels are very high. thy­roid hormones are sometimes present in either abnor­mally high or low levels in people with bipolar disorder.