In vivo magnetic resonance spectroscopy (MRS) is the only noninvasive
imaging technique that can directly assess the living biochemistry
in localized brain regions. In the past decade, spectroscopy studies
have shown biochemical alterations in various neuropsychiatric disorders.
These first-generation studies have, in most cases, been exploratory
but have provided insightful biochemical information that has furthered
our understanding of different brain disorders. This review provides
a brief description of spectroscopy, followed by a literature review
of key spectroscopy findings in schizophrenia, affective disorders,
and autism.
In schizophrenia, phosphorus spectroscopy studies have shown altered
metabolism of membrane phospholipids (MPL) during the early course
of the illness, which is consistent with a neurodevelopmental abnormality
around the critical period of adolescence when the illness typically
begins. Children and adolescents who are at increased genetic risk
for schizophrenia show similar MPL alterations, suggesting that
schizophrenia subjects with a genetic predisposition may have a
premorbid neurodevelopmental abnormality.
Independent of medication status, bipolar subjects in the depressive
state tended to have higher MPL precursor levels and a deficit of
high-energy phosphate metabolites, which also is consistent with
major depression, though these results varied. Further bipolar studies
are needed to investigate alterations at the early stage.
Lastly, associations between prefrontal metabolism of high-energy
phosphate and MPL and neuropsychological performance and reduced
N-acetylaspartate in the temporal and cerebellum regions have been
reported in individuals with autism. These findings are consistent
with developmental alterations in the temporal lobe and in the cerebellum
of persons with autism. This paper discusses recent findings of
new functions of N-acetylaspartate.
(Can J Psychiatry 2002;47:315–326)
Key Words: in vivo, proton, phosphorus, spectroscopy,
schizophrenia, bipolar, depression, autism
Résumé : La spectroscopie
par résonance magnétique in vivo et son application aux troubles
neuropsychiatriques
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