5-HT1A receptor binding in euthymic bipolar patients using positron emission tomography with [carbonyl-11C]WAY-100635

BackgroundThis study was undertaken to examine whether brain 5-HT1A receptor binding is reduced in euthymic bipolar patients.MethodsEight medicated euthymic bipolar patients and 8 healthy volunteers underwent positron emission tomography scanning using the selective 5-HT1A receptor radioligand [carbonyl-11C]WAY-100635.ResultsNo significant difference in global postsynaptic parametric binding potential (BPND) was found between euthymic bipolar patients (mean ± SD, 4.24 ± 0.76) and healthy volunteers (mean ± SD, 4.34 ± 0.86). Ninety five percent Confidence Intervals for the difference in group mean global postsynaptic BPND were - 0.77 to 0.97. Analysis of regional BPND did not reveal regional differences between patients and healthy controls.LimitationsThe number of subjects studied was limited and all subjects were on medication.ConclusionsIn contrast to previous findings of reduced 5-HT1A receptor binding in untreated unipolar and bipolar depressed patients [Sargent, P.A., Kjaer, K.H., Bench, C.J., Rabiner, E.A., Messa, C., Meyer, J., Gunn, R.N., Grasby, P.M., Cowen, P.J., 2000. Brain serotonin1A receptor binding measured by positron emission tomography with [11C]WAY-100635: effects of depression and antidepressant treatment. Arch. Gen. Psychiatry 57, 174-180]; [Drevets, W.C., Frank, E., Price, J.C., Kupfer, D.J., Holt, D., Greer, P.J., Huang, Y., Gautier, C., Mathis, C., 1999. PET imaging of serotonin1A receptor binding in depression. Biol. Psychiatry 46, 1375-1387] and in recovered unipolar depressed patients [Bhagwagar, Z., Rabiner, E.A., Sargent, P.A., Grasby, P.M., Cowen, P.J., 2004. Persistent reduction in brain serotonin1A receptor binding in recovered depressed men measured by positron emission tomography with [11C]WAY-100635. Mol. Psychiatry 9, 386-92], this study found no difference in 5-HT1A receptor BPND between medicated euthymic bipolar patients and healthy controls. Normal 5-HT1A receptor BPND in these patients may be a result of drug treatment or could indicate that reduced 5-HT1A receptor binding is specific to the depressed state in bipolar patients.