D-Serine is a naturally occurring substance in the brain that activates the N-methyl-d-aspartate-type glutamate receptor (NMDAR). This receptor is thought to be important in both schizophrenia and plasticity (learning). My model proposes that problems with NMDAR within the brain leads to impaired plasticity, which in turn leads to impaired cognition. d-serine is an ideal NMDAR activator to study because it balances efficacy, availability and safety. Most d-serine studies have used a low dose, but the evidence for efficacy is even stronger for high dose d-serine, as will be tested in the current study. There has only been limited summary of higher dose d-serine, which is another important reason for this study.~In addition to testing a potentially viable treatment in schizophrenia, a positive result would provide opportunities for use of D-serine in other populations (e.g. anxiety disorders or dementia) and stimulate the pharmaceutical industry to utilize this methodology to assess the efficacy of novel NMDAR modulators, using d-serine as a gold-standard.~The ultimate goal of this two part grant (R61-R33) study is to improve cognitive remediation by augmenting with D-serine.~We recently completed the R61-phase, meeting our predetermined milestones.  As predicted, D-serine led to significant enhancement of auditory plasticity and electrophysiological measures.~During the three-year R33-phase, we will conduct a study of D-serine of 60 schizophrenia patients, assessing the effects of D-serine over 16 sessions of this program. Most successful, cognitive remediation programs are limited by lengthy (30-50 hours) treatments. Hypothesizing that adding D-serine will increase efficiency of cognitive remediation, successful completion of the R33-phase is defined as significant improvement in global cognition after 16 hours of treatment, and will serve as a pilot study to determine whether future, definitive clinical trials are warranted.
Schizophrenia is a major public health problem associated with cognitive deficits, such as short and long term memory, executive functioning, attention and speed of processing that are amongst the strongest predictors of impaired functional outcome. In addition, schizophrenia patients show reduced plasticity, defined as reduced learning.~D-serine is a naturally occurring activator of the N-methyl-d-aspartate-type glutamate receptors (NMDAR) in the brain, and this project will assess the D-serine treatment over 16 weeks of a program designed to measure auditory plasticity.