SINGLE-VOXEL H-1-MRS INVESTIGATION OF BRAIN METABOLIC CHANGES DURING LACTATE-INDUCED PANIC

Intravenous sodium lactate infusion is a robust laboratory technique f or eliciting panic in susceptible individuals. The objective for this study was to replicate previous work which found differential brain la ctate rises among lactate-sensitive panic subjects relative to control subjects using single-voxel H-1-magnetic resonance spectroscopy (MRS) . Single-voxel H-1-MRS was used to measure brain lactate changes in th e insular cortex region among 13 panic disorder subjects and 10 health y control subjects during the infusion. One panic subject prematurely terminated the study due to a panic response during lactate infusion. Data from two additional control subjects and one panic subject were l ost due to technical problems. Four panic subjects were reinfused with lactate while panic-free under treatment with fluoxetine (20 mg/day). At the time of initial infusion, all subjects were medication-free fo r at least 1 month. Ten panic subjects, but no control subjects, panic ked during lactate infusion. In comparison to control subjects, panic subjects demonstrated significantly greater and prolonged brain lactat e rises in the insular cortex region. Three of four medicated panic su bjects experienced blockage of panic symptoms during lactate reinfusio n but all exhibited persistent excesses in brain lactate rise. Consist ent with our prior observations, greater and prolonged lactate rises i n the insular brain region occur during and following lactate infusion among panic subjects compared to control subjects. This differential brain metabolic response did not appear to normalize when a small subs et of panic patients were reinfused following resolution of panic symp toms during treatment over 3-4 months with fluoxetine. (C) 1997 Elsevi er Science Ireland Ltd.