BD youth show altered frontal lobe bioenergetic metabolism

By Mark Cowen

Results from a US study suggest that depressed unmedicated adolescents with bipolar disorder (BD) have altered frontal lobe mitochondrial function.

Xian-Feng Shi (University of Utah, Salt Lake City) and team found that unmedicated adolescents with BD depression had decreased frontal lobe inorganic phosphate (Pi) levels and increased phosphocreatine (PCr) levels and PCr/Pi ratio compared with medicated patients and mentally healthy individuals (controls).

"If replicated by other investigators, the finding of reduced frontal lobe Pi concentration in medication-free adolescents with bipolar depression could serve as an initial step toward establishing a biomarker for the illness," comment the researchers in Bipolar Disorders.

In total, eight unmedicated and six medicated adolescents with BD depression and 24 controls were assessed for neurometabolite levels in the frontal lobe using phosphorus-31 magnetic resonance spectroscopy (³¹P-MRS).

All of the participants were aged 13‑18 years, and there were no significant between-group differences regarding age, educational level, or handedness.

Post-hoc analysis revealed that Pi levels were reduced by 17% and 24% in unmedicated BD patients compared with controls and medicated BD patients, respectively.

Furthermore, PCr levels were increased by 11% in unmedicated BD patients compared with controls, while there was no significant difference in PCr levels between medicated BD patients and controls.

The PCr/Pi ratio was also increased by 24% and 39% in unmedicated BD patients compared with controls and medicated BD patients, respectively.

There were no significant between-group differences in levels of beta-nucleoside triphosphate, however.

Shi et al conclude: "Additional ³¹P-MRS studies of pediatric BD are indicated, including larger-scale studies aimed at biomarker identification and longitudinal investigations designed to elucidate the natural history of BD and the effects of treatment."

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