Pharmacogenetic Treatment With Anti-Glutaminergic Agents for Comorbid PTSD & AUD

The primary study objective is to determine the efficacy of pregabalin administered orally for a period of 12 weeks in reducing risky drinking and symptoms of posttraumatic stress disorder who have selected genotypes at the gamma-amino butyric acid transporter and receptor genes. The secondary objective is to assess the safety and tolerability of pregabalin in participants with alcohol use disorder and co-occurring posttraumatic stress disorder who have selected genotypes at the gamma-amino butyric acid transporter and receptor genes. The investigators will utilize a sample of African-Americans that includes both genders and individuals with different types of trauma.

Nearly 60% of individuals with posttraumatic stress disorder (PTSD) have a comorbid alcohol use disorder (AUD). This comorbidity is associated with more severe PTSD symptoms, higher rates of psychosocial and medical problems, higher relapse rates, and poorer treatment outcome. Pre-clinical studies have indicated that PTSD and AUD share common molecular underpinnings. Particularly, the adaptations in the brain neurotransmitter systems to chronic excessive drinking that are evident during alcohol withdrawal share similarities with PTSD cluster B and E symptoms (characterized by symptoms of re-experiencing and hyper-arousal), which initiate a cycle of relapse into excessive drinking and worsening of PTSD symptoms. Excessive glutamate and reduced gamma-amino butyric acid (GABA) neurotransmitter concentrations were found in various brain regions in individuals with co-morbid PTSD/AUD. The anticonvulsant pregabalin (with high affinity for the alpha-2-delta auxiliary site of voltage gated calcium channels) that modulates the effects of the GABA transporter (GAT-1) and increases its density of GABA, has shown preliminary efficacy in reducing drinking in AUD with comorbid generalized anxiety disorder, and improves outcomes from PTSD. Large scale studies with ample statistical power in VA settings and community populations, with diverse combat and non-combat related trauma, are now warranted to evaluate the promising preliminary evidence that pregabalin can improve outcomes for those with AUD and PTSD. An important personalized medicine approach to optimize pregabalin efficacy would be to select individuals with AUD and PTSD with genetic variation at the GAT-1 transporter so as to match its potential therapeutic effects with specific types of individual. In African-Americans, variants at the SLC6A1 gene promoter region insertion (i.e., non-insertion/insertion or insertion/insertion (NI/I or I/I) compared with those of Non-insertion/Non-insertion (NI/NI) type have significantly higher levels of GAT-1promoter activity. The investigators will, therefore, segregate our target sample by genetic variation at the GAT-1 transporter. Because of the low allelic frequency of individuals with the double copy insertion, the investigators will combine these into one group with those with the single copy (i.e., NI/I/II). This study will test the efficacy of pregabalin in reducing both alcohol consumption and PTSD symptoms in 2 treatment groups of medication (pregabalin 450 mg/day and placebo) x 2 genetic variants (NI/I/II vs. NI/NI) in a double- blind, placebo-controlled 14-week clinical trial (screening, 12 weeks of study medication, follow-up call). After a one-week screening period, pregabalin dose (and placebo) will be titrated to the target dose from baseline to week 3 using a double-dummy procedure to ensure equivalence of capsules received. The investigators will utilize a sample of African-American participants with co-occurring AUD and PTSD that includes both genders and individuals with different types of trauma. Participants will receive standardized discussions to enhance compliance with study medication at all visits. The specific aims are: Specific Aim 1: Independent of race, to test the hypothesis that AUD/PTSD participants treated with pregabalin will demonstrate a greater reduction in heavy drinking than placebo treated participants. Specific Aim 2: Independent of race, to test the hypothesis that AUD/PTSD participants treated with pregabalin will demonstrate a greater reduction in PTSD cluster B or E symptoms (or both) than placebo-treated participants. Specific Aim 3: To test the hypothesis that race will moderate the effects of pregabalin examined in Aims 1 and 2. Specific Aim 4: To test the hypothesis that the treatment responses to pregabalin specified in Aims 1 and 2 are modulated by genetic variations within SLC6A1 gene in AUD/PTSD in both African American and European American populations.