Glucocorticoid interactions with memory function in schizophrenia

Glucocorticoid (GC) exposure can affect brain function, including potential adverse effects on hippocampal physiology and on specific elements of cognitive performance. In a prior study of healthy adult humans, decreased verbal memory performance was detected during four days of double-blind, placebo-controlled dexamethasone (DEX) treatment. Using an identical experimental design and sample size (n = 19), the cognitive effect of DEX treatment was studied in 11 subjects with schizophrenia, compared with 8 receiving placebo. In contrast to the effect in healthy adults, GC treatment with DEX at this dose (cumulative 3.5 mg) and duration did not decrease verbal memory performance or other measures of cognitive function in the patients with schizophrenia. When data from this experiment was compared with data from the previous study of healthy adults, covarying differences in baseline memory performance, a significant 3-way interaction was detected between subject group, treatment condition, and the repeated measurements of verbal memory performance across baseline, treatment and washout (F[3,87] = 4.84, p = .0066), suggesting differential cognitive effects of DEX in the patients versus the previously studied healthy subjects. Baseline plasma cortisol concentrations (0800h) prior to DEX treatment were inversely correlated with baseline delayed (r(s) = - 0.536, p = .03) verbal recall performance, supporting a previous report. The current results await replication using a larger sample size but provide preliminary evidence for an altered behavioral response to acute GC exposure in schizophrenic versus healthy subjects, and further evidence for a relationship between chronic changes in circulating cortisol and the memory impairments found in this disorder.