A systematic review and meta-analysis of proton magnetic resonance spectroscopy and mismatch negativity in bipolar disorder

Alterations of cerebral glutamate in the euthymic state of patients with bipolar disorder

“…Our finding of increased glutamate levels supports previous assumptions that a disturbed glutamatergic neurotransmission in the ACC plays an important role in the pathophysiology of bipolar disorder (Gigante et al, 2012;Chitty et al, 2013). Our finding is consistent with the recent observation of increased glutamate/ creatine ratios and glutamine þ glutamate/creatine ratios in the ACC of euthymic bipolar patients (Soeiro-de-Souza et al, 2013).…”

“…However, others could not confirm that finding (Davanzo et al, 2001;Singh et al, 2010), a failure which might be due to the high rate of comorbidity in some studies (e.g., attention deficit hyperactivity disorder, anxiety disorder, disruptive behavior disorder, and posttraumatic stress disorder) with effects on the reported results. The hypothesis that reduced glial density or impaired astrocyte function (Ongur et al, 1998) in the ACC of bipolar patients is linked to a substantial accumulation of synaptic glutamate (Chitty et al, 2013) was corroborated by the present study. Accordingly, in line with Ongur et al (2008), it appears plausible to suggest that an increased glutamate level is associated with glutamatergic overactivity.…”

Alcohol use in bipolar disorder: A neurobiological model to help predict susceptibility, select treatments and attenuate cortical insult

“…However, recent evidence suggests that MMN impairments also exist in BD (Andersson et al, 2008;Jahshan et al, 2012;Kaur et al, 2012;Shimano et al, 2014), which was corroborated by our meta-analysis of the seven available studies suggesting that overall, frontal MMN amplitude is moderately impaired in BD (Chitty et al, 2013b). It is noteworthy however, that the calculated effect size was considerably smaller than that reported in a schizophrenia MMN metaanalysis (Umbricht et al, 2005), which may suggest that the impairments in BD are not as pronounced, or may reflect the substantially lower number of available studies in BD.…”

The Neurobiology of Bipolar Disorder: Neuroimaging and Genetics Update

“…The evidence to date suggests that there are alterations in several key neuroregulators in BD, although further evidence is required to resolve or clarify inconsistencies in results (27)(28)(29). A recent meta-analysis suggests that glutamate and glutamine concentrations are increased in the frontal cortex in patients with BD compared with controls (28), which may point to alterations in N-methyl-d-aspartate (NMDA) receptor function.…”

“…The evidence to date suggests that there are alterations in several key neuroregulators in BD, although further evidence is required to resolve or clarify inconsistencies in results (27)(28)(29). A recent meta-analysis suggests that glutamate and glutamine concentrations are increased in the frontal cortex in patients with BD compared with controls (28), which may point to alterations in N-methyl-d-aspartate (NMDA) receptor function. N-acetyl aspartate (NAA) is a metabolite thought to index neuronal integrity and, in particular, axon functioning; evidence suggests that NAA levels may be decreased in the basal ganglia (30) as well as in the frontal lobe (29) in BD.…”