There is evidence that neuroinflammation plays a role in the pathology of bipolar disorder, but further investigation is necessary to determine whether or not microglia are involved in this. However, microglia do appear to be overactive in the context of BD during both the manic and depressive phases, and they under-produce BDNF, which is involved in synaptic plasticity. There is some gene expression that differentiates the microglial function in BD patients and those with schizophrenia, as well as differences in postmortem microglia expression in BD patients who died by suicide versus those who did not, with the non-suicide group expressing lower levels of microglia density. Typical mood stabilizer treatments (lithium and valproic acid) seem to act on microglia, but the mechanism is unknown.