Effects of S-adenosylmethionine augmentation of serotonin-reuptake inhibitor antidepressants on cognitive symptoms of major depressive disorder.

UNLABELLED: Major depressive disorder (MDD) is often accompanied by significant cognitive impairment, and there are limited interventions specific to this particular symptom. S-adenosylmethionine (SAMe), a naturally occurring molecule which serves as a major methyl-donor in human cellular metabolism, is required for the synthesis and maintenance of several neurotransmitters that have been implicated in the pathophysiology and treatment of cognitive dysfunction in MDD. OBJECTIVES: This study is a secondary analysis of a clinical trial involving the use of adjunctive SAMe for MDD. METHODS: Forty-six serotonin-reuptake inhibitor (SRI) non-responders with MDD enrolled in a 6-week, double-blind, randomized trial of adjunctive oral SAMe were administered the self-rated cognitive and physical symptoms questionnaire (CPFQ), a validated measure of cognitive as well as physical symptoms of MDD, before and after treatment. RESULTS: There was a greater improvement in the ability to recall information (P=0.04) and a trend towards statistical significance for greater improvement in word-finding (P=0.09) for patients who received adjunctive SAMe than placebo. None of the remaining five items reached statistical significance. CONCLUSIONS: These preliminary data suggest that SAMe can improve memory-related cognitive symptoms in depressed patients, and warrant replication.

Neurocognitive functions of heavy cannabis using schizophrenia patients.

This current study assessed neurocognitive functioning in a carefully selected sample of schizophrenia patients with and without heavy cannabis use and healthy controls. All subjects were negative for any other substance use. Schizophrenia subjects had impaired neurocognitive functions across a wide range of tasks compared to healthy controls. Cannabis using schizophrenia patients had focused impairments on tasks of attention, and the findings suggest an impulsive pattern of response among these patients.

Blockade of NGF-induced neurite outgrowth by a dominant-negative inhibitor of the egr family of transcription regulatory factors.

Although it is well established that members of the Egr family of transcription regulatory factors are induced in many neuronal plasticity paradigms, it is still unclear what role, if any, they play in this process. Because NGF stimulation of pheochromocytoma 12 cells elicits a robust induction of Egr family members, we have investigated their role in mediating long-term effects elicited by NGF in these cells by using the Egr zinc finger DNA-binding domain as a selective antagonist of Egr family-mediated transcription. We report that expression of this Egr inhibitor construct suppresses neurite outgrowth elicited by NGF but not by dibutyryl cAMP. To check that this Egr inhibitor construct does not act by blocking the MEK/ERK pathway, which is known to mediate NGF-induced neurite outgrowth, we confirmed that the Egr inhibitor construct does not block NGF activation of Elk1-mediated transcription, a response that is dependent on this pathway. Conversely, inhibition of MEK does not impair Egr family-mediated transcription. Thus, we conclude (1) that induction of Egr family members and activation of the MEK/ERK pathway by NGF are mediated by separate signaling pathways and (2) that both are required to trigger neurite outgrowth induced by NGF.