Effects of glucocorticoids on declarative memory function in major depression

Specificity of autobiographical memories and basal cortisol levels in patients with major depression

This study investigated whether over-general retrieval of autobiographical memories in depression is related to increased basal cortisol levels. Forty-seven individuals with a current diagnosis of major depression were given the autobiographical memory test, in which they were asked to produce specific autobiographical memories following positive, negative and neutral cue words. Salivary cortisol samples were taken at fixed time intervals during testing in the afternoon. Basal cortisol levels did not appear to be markedly elevated and were not significantly correlated with autobiographical memory performance. There were, however, strong negative correlations between memory specificity and decreases of cortisol levels over time of testing. Findings suggest that while specificity of autobiographical memory may be sensitive to cortisol changes, the occurrence of over-general memory in depression is not necessarily due to increased cortisol levels.

Effects of phenytoin on memory, cognition and brain structure in post-traumatic stress disorder: a pilot study

Phenytoin (Dilantin) is an anticonvulsant used in the treatment of epilepsy. It is believed to act by modulation of glutamatergic transmission. Because the neurobiology of post-traumatic stress disorder (PTSD) has been hypothesized to involve alterations in glutamatergic transmission with subsequention neurotoxicity, we assessed the effects of phenytoin on cognition and brain structure in PTSD patients. Phenytoin was administered in an open label fashion for 3 months to nine adult patients with PTSD related to a variety of traumas, including early abuse, combat and car accidents. Subjects underwent magnetic resonance imaging for measurement of whole brain and hippocampal volume, and neuropsychological testing of memory and cognition, before and after treatment. Phenytoin treatment resulted in a significant 6% increase in right brain volume (p < 0.05). Increased hippocampal volume was correlated with reductions in symptom severity as measured by the Clinician Administered PTSD Scale and improvements in executive function as measured by the Trails test. However, treatment associated improvements in memory and cognition did not achieve statistical significance. These findings suggest that phenytoin treatment may be associated with changes in brain structure in patients with PTSD.

Effect of phenytoin on mood and declarative memory during prescription corticosteroid therapy

BACKGROUND

In humans and animals, corticosteroid excess is associated with impairment in declarative memory and changes in hippocampal structure. In animals, phenytoin pretreatment blocks the effects of stress on memory and hippocampal histology, although no studies have examined the use of phenytoin to prevent corticosteroid-associated memory changes in humans. Mood changes are also common with corticosteroids, but few treatment data are available. This report examines whether phenytoin can prevent mood or declarative memory changes secondary to bursts of prescription corticosteroids.

METHODS

Thirty-nine patients with allergies or pulmonary or rheumatologic illnesses and given systemic corticosteroid therapy were randomized to receive either phenytoin (300 mg/day) or placebo concurrently with the corticosteroids. Mood was assessed with the Hamilton Rating Scale for Depression, Young Mania Rating Scale, and Activation (ACT) subscale of the Internal State Scale; declarative memory was assessed with the Rey Auditory Verbal Learning Test (RAVLT) at baseline and after approximately 7 days of corticosteroid plus phenytoin or placebo therapy.

RESULTS

The two groups were similar in age, gender, education, and corticosteroid dose. The phenytoin-treated group showed significantly smaller increases on the ACT, a mania self-report scale, than the placebo-treated group. Groups did not differ significantly on RAVLT change scores.

CONCLUSIONS

This is the first placebo-controlled study to examine whether a medication can prevent mood and memory changes secondary to corticosteroids. Phenytoin blocked the hypomanic effects of prescription corticosteroids; however, phenytoin did not block the declarative memory effects of corticosteroids.

Glucocorticoid receptor function in vitro in patients with major depression

Clinical studies have demonstrated an impairment of glucocorticoid receptor (GR)-mediated negative feedback on the hypothalamic--pituitary--adrenal (HPA) axis in patients with major depression (GR resistance), and its resolution by antidepressant treatment. Interestingly, a number of studies have also demonstrated that GR function is reduced in vitro, in peripheral tissues of depressed patients, as shown by a decreased sensitivity to the effects of glucocorticoids on immune and metabolic functions. This paper reviews the in vitro studies that have examined GR function in patients with major depression, and the possible molecular mechanisms involved in GR resistance. Since several studies have demonstrated similar regulation of GR in the brain and in peripheral tissues in humans, and given limited access to brain GR in clinical populations, this review claims that in vitro studies are of particular relevance to understand the molecular mechanisms underlying GR abnormalities in patients with major depression and its regulation by antidepressant treatment.

Effects of dexamethasone on declarative memory function in posttraumatic stress disorder

Alterations in the hypothalamic-pituitary-adrenal (HPA) axis and hippocampal-based memory have been associated with posttraumatic stress disorder (PTSD), and the administration of exogenous glucocorticoids has been shown to result in a transient verbal declarative memory impairment in healthy human subjects. The purpose of this study was to assess the effects of the glucocorticoid dexamethasone on verbal declarative memory function in patients with PTSD. Forty-two men and women with (n=14) and without (n=28) PTSD received placebo or dexamethasone (1 and 2 mg on two successive days) in a double-blind, randomized fashion. Declarative memory was assessed with paragraph recall at baseline (day 1) and day 3. There was a significant interaction between diagnosis and drug (dexamethasone vs. placebo) on paragraph recall related to a relative detrimental effect of dexamethasone on memory function in healthy subjects, but not those with PTSD. These findings are consistent with an altered sensitivity of declarative memory function in PTSD to regulation by glucocorticoids, possibly explainable by alterations in glucocorticoid receptors in the hippocampus or other brain regions mediating declarative memory.