1H magnetic resonance spectroscopy investigation of the dorsolateral prefrontal cortex in bipolar disorder patients Academic Article uri icon

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abstract

  • BACKGROUND: Magnetic resonance spectroscopy studies (MRS) reported abnormally low levels of N-acetylaspartate (NAA, a marker of neuronal integrity) in dorsolateral prefrontal cortex (DLPFC) of adult bipolar patients, suggesting possible neuronal dysfunction. Furthermore, recent MRS reports suggested possible lithium-induced increase in NAA levels in bipolar patients. We examined with in vivo (1)H MRS NAA levels in the DLPFC of adult bipolar patients. METHODS: Ten DSM-IV bipolar disorder patients (6 lithium-treated, 4 drug-free) and 32 healthy controls underwent a short echo-time 1H MRS session, which localized an 8 cm3 single-voxel in the left DLPFC using a STEAM sequence. RESULTS: No significant differences between the two groups were found for NAA, choline-containing molecules (GPC+PC), or phosphocreatine plus creatine (PCr+Cr) (Student t-test, p > 0.05). Nonetheless, NAA/PCr+Cr ratios were significantly increased in lithium-treated bipolar subjects compared to unmedicated patients and healthy controls (Mann-Whitney U-test, p < 0.05). LIMITATIONS: Relatively small sample size may have reduced the statistical power of our analyses and the utilization of a single-voxel approach did not allow for the examination of other cortical brain areas. CONCLUSIONS: This study did not find abnormally reduced levels of NAA in left DLPFC of adult bipolar patients, in a sample of patients who were mostly on medications. However, elevated NAA/PCr+Cr ratios were shown in lithium-treated bipolar patients. Longitudinal 1H MRS studies should further examine NAA levels in prefrontal cortex regions in untreated bipolar patients before and after mood stabilizing treatment.

authors

  • Brambilla, Paolo
  • Stanley, Jeffrey A
  • Nicoletti, Mark A
  • Sassi, Roberto
  • Mallinger, Alan G
  • Frank, Ellen
  • Kupfer, David
  • Keshavan, Matcheri S
  • Soares, Jair C

publication date

  • May 2005