BDNF is well-understood to be critical in cognitive function via neural plasticity and affected by inflammatory states,19 so it is unsurprising that this neurotrophic factor has been found as attenuated in the presence of cognitive impairment in bipolar disorder.55 Known to be particularly implicated in memory synthesis via neuronal action in the hippocampus, cortex and basal forebrain,56 it is possible that the BDNF–cognition association in our study did not reach significance because cognition was measured as a global construct, rather than domain-specific comparisons. The gene discussed is BDNF; the disease is bipolar disorder.