Brain perfusion during manic episode and at 6-month follow-up period in bipolar disorder patients: Correlation with cognitive functions

Background Patterns of altered cerebral perfusion and cognitive dysfunction have been described in Bipolar Disorder (BD) acute episodes and euthymia. Knowledge of the relationship between cognitive function and perfusion in a manic state and status when followed up is still limited. Objective To describe brain perfusion alterations and its relationship with cognitive impairment in patients with BD during manic episodes and after 6 months. Methods Observational-prospective study in 10 type I BD adults during moderate-severe manic episodes. We assessed sociodemographic data and clinical variables as well as cognitive function through Screening for Cognitive Impairment in Psychiatry (SCIP-S). Finally, we performed a Brain Perfusion SPECT using a Tc99m-ethyl cysteine dimer. Results During manic episodes, patients showed cognitive impairment with a mean SCIP-S score of 63.8 +/- 17.16. This was positively correlated with perfusion measured as relative reuptake index (RRI) at the right temporal pole (rho = 0.65 p = .0435) and negatively correlated with right the orbitofrontal cortex (rho = -0.70 p = .0077) and the right subgenual cingulate cortex (rho = -0.70 p = .0256). Episode severity measured by the Young Mania Rating Scale (YMRS) positively correlated with RRI at the right temporal pole (rho = 0.75, p = .01). At follow-up, six patients were taking treatment and were euthymic, we found a negative correlation with the YMRS and RRI at the bilateral orbitofrontal cortex (rho = -0.8827, p = .019). They did not show significant improvement in cognitive performance at SCIP-S, and there was negative correlation with the following of the SCIP-S subscales; processing speed with the bilateral dorsolateral prefrontal, the bilateral medial prefrontal, the left temporal pole cortex RRI, and verbal fluency with the bilateral anterior cingulate cortex RRI. Conclusion Cognitive impairment was correlated with brain perfusion patterns at baseline and follow-up. Large sample size studies with longer follow-up are needed to describe the changes in perfusion and cognitive functions in BD.