DIETARY TREATMENT OF PTSD IN VETERANS WITH GULF WAR ILLNESS

Veterans who served in the Gulf War commonly experience a multi-symptom neurological illness called Gulf War Illness (GWI) that stems from chemical exposures during the 1990-1991 conflict. This commonly co-occurs with post-traumatic stress disorder (PTSD), which is a trauma and stress related disorder that is marked by intrusive re-experiencing (e.g., flashbacks, nightmares), avoidance of trauma-associated stimuli (e.g., triggers), hyperarousal (e.g., augmented startle response), and negative changes in mood and cognition (e.g., depression, amnesia). Both GWI and PTSD involve excessive excitation by glutamate in the brain, a process called excitotoxicity, in which cells are overstimulated to the point of apoptosis. The low glutamate diet, which eliminates dietary free glutamate (i.e., glutamate which is not bound to a protein), aims to reduce excitotoxicity, and thus ameliorate symptoms for PTSD and GWI. In past research, the diet has been effective in treating both PTSD and GWI. The current study aims to confirm the treatment efficacy of the low glutamate diet for PTSD, and whether biomarkers of PTSD, including serum cortisol and cortical excitation in the brain, change in response to the diet and in relation to PTSD improvement. Data were analyzed for 41 veterans with GWI comparing changes after one-month on the low glutamate diet. Blood was collected at baseline and post-diet lab visits to obtain plasma glutamate and serum cortisol concentrations, and electroencephalography (EEG) recordings were collected at both timepoints to observe changes in brain cortical excitation. PTSD severity reduced by a significantly larger magnitude in the experimental group after the dietary month, which they started immediately, compared to waitlisted controls who followed their normal eating habits for the first month. PTSD significantly reduced after one month on the low glutamate diet in the whole sample. Better dietary adherence was associated with reductions in gamma power in frontal, central, and posterior regions of the brain (relative power, eyes closed), and these models were adjusted for selective serotonin reuptake inhibitor (SSRI) use. The relationship between dietary adherence and reductions frontal gamma power was mediated by increases in posterior alpha power. PTSD improvement was consistently related with increases in beta power in frontal, central, and posterior brain regions (relative power, eyes open) over the dietary month. Changes in cortisol were not related to changes in PTSD in this sample, contrary to our past findings, and changes in cortisol were not related to changes in EEG power bands. Results suggest that the low glutamate diet effectively treats PTSD, reduces gamma power across the brain, and that improvements in PTSD are associated with increases in beta power throughout the brain.