No Differences Between Bipolar Patients and Normal Controls in Inositol Levels and Inositol Monophosphatase Activity in Postmortem Brain

The discovery of inositol monophosphatase (IMPase) activity inhibition by lithium (Li) ions led to Berridge’s inositol depletion hypothesis, and brain inositol levels have been studied in relation to psychiatric disorders. We have previously reported low myo-inositol levels in the frontal cortex of bipolar and schizophrenic patients and low IMPase activity in lymphocyte-derived cell lines from this group of patients. In the present study, myo- and scyllo-inositol levels and IMPase activity were measured in the Stanley Brain Consortium postmortem brain specimens from bipolar patients and normal controls. No differences were found between the diagnostic groups in any parameter in any brain area studied. There was a positive correlation between myo- and scyllo-inositol in frontal and occipital cortex. We could not replicate our previous report of low myo-inositol levels in the frontal cortex of bipolar patients. In subjects treated with neuroleptic drugs, there was no correlation between myo-inositol levels and estimated chlorpromazine equivalents administered peri mortem.