Cognitive and functional recovery at 6 and 12 months post-TBI.

Outcome studies examining recovery from traumatic brain injury (TBI) often fail to provide a clear understanding of the time course of cognitive, emotional, and behavioural recovery. The present study represents an effort to prospectively study individuals with TBI at fixed intervals, specifically 6 and 12 months post-injury with a window of +/- 1 month. Seventy-two individuals with new-onset TBI underwent neuropsychological evaluation and clinical interview at 6 and 12 months post-injury. Results revealed significant improvements in cognitive abilities, including memory, processing speed, language abilities, and constructional skills. There were significant gains in community integration and involvement in productive activities, but limitations in driving activities remained. Although individuals with mild-moderate TBI performed better than individuals with severe TBI, both groups demonstrated equivalent rates of recovery across domains. The results of this study provide important information regarding the time course of TBI recovery.

Decreased memory performance in healthy humans induced by stress-level cortisol treatment.

BACKGROUND: Glucocorticoids (GCs) can regulate hippocampal metabolism, physiologic functions, and memory. Despite evidence of memory decreases during pharmacological GC treatment, and correlations between memory and cortisol levels in certain disease conditions, it remains unclear whether exposure to the endogenous GC cortisol at levels seen during physical and psychological stress in humans can inhibit memory performance in otherwise healthy individuals. METHODS: Randomized, double-blind, placebo-controlled comparison of 2 fixed oral doses of cortisol (40 mg/d and 160 mg/d using split doses to approximate circadian rhythm) given for 4 days to matched groups of healthy subjects (n = 51). Lower-dose treatment approximated cortisol exposure during mild stress, whereas the higher dose approximated cortisol exposure during major stress. Cognitive testing and plasma sampling were done at baseline, after 1 and 4 days of treatment, and after a 6-day washout period, hypothesizing dose-dependent decreases in verbal declarative memory. RESULTS: Cortisol treatment at the higher dose produced reversible decreases in verbal declarative memory without effects on nonverbal memory, sustained or selective attention, or executive function. A significant interaction between time and treatment condition for paragraph recall was explained by treatment-induced differences in performance after 4 treatment days, with lower immediate and delayed recall performance during higher-dose cortisol treatment compared with lower-dose treatment and placebo. CONCLUSIONS: Several days of exposure to cortisol at doses and plasma concentrations associated with physical and psychological stress in humans can-similar to pharmacological GC treatment-reversibly decrease specific elements of memory performance in otherwise healthy individuals.