Adolescent anorexia nervosa: cross-sectional and follow-up frontal gray matter disturbances detected with proton magnetic resonance spectroscopy.

There are very few magnetic resonance spectroscopy studies in anorexia nervosa and none of them with young adolescent patients. We studied 12 anorexia nervosa (DSM-IV) patients aged 11-17 consecutively admitted to an Eating Disorders Unit. An evaluation with laboratory data, psychopathological scales, magnetic resonance spectroscopy ((1)H MRS) and a neuropsychological battery was carried out at admission and after 7 months' follow-up and weight recovery. Psychopathological and neuropsychological and MRS examinations were also performed in 12 control subjects. In the MRS study at the frontal gray matter, the anorexic group had a significantly lower N-acetyl-aspartate (NAA) (p = .002), glutamate/glutamine (Glx) (p = .010) and myo-Inositol (mI) (p = .022) than the control group. The NAA correlated positive and significantly with triiodothyronin (Rho = .64) and the estimate level of intelligence measured with the vocabulary subtest of the WISC-R (Rho=.64). There were also positive correlations with body mass index (Rho = .47) and with attention measured with the coding subtest of the WISC-R (Rho=.51) and negative with loss of weight (Rho = -.51) but they were not statistically significant. At follow-up, there was an increase in body mass index (p=.002), triiodothyronin (p = .005), and insulin-like growth factor 1 (p = .017) and a decrease in cortisol (p = .005). In the MRS a significant increase (p = .013) in NAA was observed. The conclusion would be that NAA, Glx and mI are low in the frontal gray matter of adolescents with anorexia nervosa and specially NAA correlates with some nutritional and cognitive parameters. These alterations seem to be reversible in young patients.