Antagonism of N-methyl-D-aspartate glutamatergic receptors (NMDAR) may represent an effective antidepressant mechanism. D-cycloserine (DCS) is a partial agonist at the NMDAR-associated glycine modulatory site that at high doses acts as a functional NMDAR antagonist. Twenty-six treatment-resistant major depressive disorder patients participated in a double blind, placebo-controlled, 6-wk parallel group trial with a gradually titrated high dose (1000 mg/d) of DCS added to their antidepressant medication. DCS treatment was well tolerated, had no psychotomimetic effects and led to improvement in depression symptoms as measured by Hamilton Depression Rating Scale (HAMD; p = 0.005) and Beck Depression Inventory (p = 0.046). Of the 13 subjects treated with DCS, 54% had a ≥ 50% HAMD score reduction vs. 15% of the 13 patients randomized to placebo (p = 0.039). A significant (p = 0.043) treatment× pre-treatment glycine serum levels interaction was registered. These findings indicate that NMDAR glycine site antagonism may be a cost-effective target for development of mechanistically novel antidepressants. Larger-sized DCS trials are warranted.
Hypnosis involves the manipulation of conscious attentional discrimination. The prepulse inhibition (PPI) paradigm assesses primary unconscious information processing. We investigated the correlation between hypnotizability and PPI of the startle reflex. Forty-eight healthy subjects were evaluated with the Stanford Hypnotic Susceptibility Scale, Form C (SHSS:C) and acoustic PPI. Subjects were divided into low, medium, and high hypnotizable groups. The low-hypnotizable group showed a significantly higher inhibition of the startle response, at lead intervals 60 ms and 120 ms, than did the medium-and highhypnotizable groups. We conclude that hypnotizability and PPI may be negatively correlated. These findings lend further support for the role of dopaminergic neurotransmission mechanisms in the determination of hypnotizability levels.
BackgroundImpairments in social behavior and cognition, such as the ability to identify others’ emotional state, are important features in schizophrenia. Arginine vasopressin (AVP) and oxytocin (OXT) and are nonapeptides that influence social cognition and behavior. Previous studies have shown that the administration of intranasal AVP or OXT may affect the ability to recognize facial emotions. The primary objective of this study was to investigate the effects of a single dose of AVP or OXT on social cognition in patients with schizophrenia. The secondary objective of the study was to test for sex-specific effects of intranasal AVP and OXT administration on social cognition.MethodsIn this double-blind, placebo-control, cross-over study, 34 patients diagnosed with schizophrenia or schizo-affective disorder, received a dose of AVP, OXT or placebo in three separate meetings. Forty-five minutes after administration, subjects performed facial emotion recognition tasks.ResultsThere were no significant main effects of hormone administration on the ability to recognize facial emotions between treatment conditions. However, AVP administration resulted in sex-specific differences in emotion recognition. Specifically, in men, AVP administration reduced the ability to recognize angry faces. In women, AVP administration reduced the ability to recognize sad faces and improved the ability to recognize fearful faces.ConclusionsThese findings indicate that intranasal AVP may affect the recognition of facial emotions differently in men and women. Thus, AVP may increase the differences between men and women on social cognition.Disclosure of interestThe authors have not supplied their declaration of competing interest.
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