Glutamate-Glutamine Cycling (VCYC) During Cocaine Abstinence Using 13C-MRS


Cocaine Dependence

Trial Phase

Phase Pilot

Trial Purpose and Description

Trial Purpose

Given prior evidence of reduced resting-state glucose uptake in prefrontal cortex (PFC) as measured by [18F]-FDG PET (Volkow 1992, 1993) and direct neurometabolic coupling of cortical glucose oxidation and glutamate transmission, we hypothesize that [13C]-MRS measures of VTCA and VCYC will be reduced in individuals abstinent from cocaine as compared to HCs. We will also explicitly explore potential relationships between VCYC and neurocognitive tests of PFC function and clinical outcomes (i.e., measures of relapse at 90-days outpatient follow-up). In addition to assessing resting-state glucose uptake in the PFC, we will explore whether open-label administration of either of three different pharmacological treatments (N-acetyl cysteine, riluzole, or pentoxifylline) increases VCYC, in cocaine users (CU) in comparison to their abstinence baseline.

Participation Guidelines

18 Years - 50 Years

Eligibility Criteria

Inclusion Criteria:

1. Age 21-50 years

2. Voluntary, written, informed consent

3. Physically healthy

4. DSM-IV criteria for Cocaine Abuse (305.60) or Cocaine Dependence (304.20)

5. Documented evidence (by urine toxicology) of abstinence from cocaine (2 weeks for
scan 1 and 4 weeks for scan 2)

6. For females, a negative serum or urine pregnancy (ß-HCG) test.

Exclusion Criteria:

1. A history of other substance dependence (e.g., alcohol, opiates, sedative hypnotics),
except for nicotine

2. A primary DSM-IV Axis I major psychiatric disorder (e.g., schizophrenia, bipolar
disorder, major depression, etc.) as determined by the Structured Clinical Interview

3. A history of significant medical (e.g., cardiovascular, diabetic/metabolic) or
neurological (e.g., cerebrovascular, seizure, traumatic brain injury) illness

4. Current use of psychotropic and/or potentially psychoactive prescription medications

5. Medical contraindications to participation in a magnetic resonance imaging procedure
(e.g., ferromagnetic implants/foreign bodies, claustrophobia, cardiac pacemaker,
prosthetic valve, otologic implant, etc.)

6. For females, physical or laboratory (ß-HCG) evidence of pregnancy

7. For subjects interested in pharmacotherapy component, history of allergies to NAC,
RIL, or PTX and current elevation on liver function tests above twice the normal

National Institute on Drug Abuse
Last Updated:
Study HIC#: