Phosphorus Spectroscopy (³¹P MRS) of the Brain in Psychiatric Disorders

Abstract

Some of the most important biological molecules responsible for the maintenance of cellular homeostasis, high-energy phosphates and phospholipids, are amenable to quantification using spectroscopy targeted at the phosphorus 31 isotope ( 31 P MRS). For example, the brain, while typically comprising 2% of the body's mass, uses 20% of its energy, and quantification of bioenergetic molecules can provide important information about cellular energy usage and storage. In addition, phospholipids, which form the basis of cellular membrane bilayers not only segregate organelles from the cellular environment and cells from the interstitial environment but are also critical in providing important second messenger signaling. The activity of these phosphorus compounds has been demonstrated to be altered in psychiatric disorders. Cellular energy utilization is demonstrably altered in mood disorders, and phospholipid metabolism is different in patients with schizophrenia when compared to normal control populations. There are challenges and complexities associated with implementing 31 P MRS, and difficulties with detection efficiency, spatial localization, and spectral quantification present challenges to the study of psychiatric disorders. Much work remains to be done in interpreting the observed bioenergetic and cell membrane changes in disease states, but continued progress in methodology and experimental design should allow for a deeper understanding of the relationship between alterations in phosphorus compounds and psychiatric disorders.