Monozygotic twins depression

Young, E.A., Aggen, S.H., Prescott, C.A., and Kendler, K.S. (2000a) Similarity in saliva cortisol measures in monozygotic twins and the influence of past major depression. Biol Psychiatry 48 70-74. 

DA, dopamine DD, depressive disorders (major depression and/or dysthymia) DZ, dizygotic twins 5-HT, serotonin p-CIT, iodine-123-labeled 2p-carbomethoxy-3p(iodophenyl) tropane MDD,major depressive disorder MRI, magnetic resonance imaging MZ, monozygotic twins NC, normal controls PC, psychiatric controls PTSD post-traumatic stress disorder rCBF, regional cerebral blood flow SPECT, single photon emission computerized tomography Tc HMPAO, technetium-99m hexamethylpropylene amine oxime. 

Bipolar disorder is characterized by episodes of mania or hypomania, which include hyperactivity, decreased need for sleep, and a euphoric or irritable mood. Additionally, persons with bipolar disorder may have episodes of depression similar to those seen in major depressive disorder. The lifetime prevalence of severe bipolar disorder is about 1% and 3-5% if milder cases are included, afflicting men and women equally. Both bipolar disorder and major depressive disorder tend to be episodic, and in the periods of time between episodes, persons may experience few or no symptoms. The etiology of bipolar disorder is predominately genetic, with a 70% concordance in monozygotic twins. The neurobiology of bipolar disorder is less well understood, and few animal models have been developed. Treatment of bipolar disorder usually involves mood stabilizer medications, including lithium, and the anticonvulsants valproate and carbamazepine. At times, antidepressant and antipsychotic medications are also used. 

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