Molecular Psychiatry
September 14, 2020
A. Mkrtchian, Jennifer W. Evans, Christoph Kraus et al.
110 citations
Ketamine improves motivation-related symptoms in depression but simultaneously elicits similar symptoms in healthy individuals, suggesting that it might have different effects in health and disease. This study examined whether ketamine affects the brain’s fronto-striatal system, which is known to drive motivational behavior. The study also assessed whether inflammatory mechanisms—which are...
Neuropsychopharmacology
August 2018
Jennifer W. Evans, Níall Lally, Li An et al.
The glutamatergic modulator ketamine has striking and rapid antidepressant effects in major depressive disorder (MDD), but its mechanism of action remains unknown. Proton magnetic resonance spectroscopy (1H-MRS) is the only non-invasive method able to directly measure glutamate levels in vivo; in particular, glutamate and glutamine metabolite concentrations are separable by 1H-MRS at 7T. This...
Psychological Medicine
December 2016
Michael Bloomfield, E Mouchlianitis, C J A Morgan et al.
Cannabis is a widely used drug associated with increased risk for psychosis. The dopamine hypothesis of psychosis postulates that altered salience processing leads to psychosis. We therefore tested the hypothesis that cannabis users exhibit aberrant salience and explored the relationship between aberrant salience and dopamine synthesis capacity. We tested 17 cannabis users and 17 age- and...
Journal of Psychopharmacology
February 17, 2015
Níall Lally, Allison C. Nugent, David A. Luckenbaugh et al.
224 citations
Anhedonia is a cardinal symptom of major depression and is often refractory to standard treatment, yet no approved medication for this specific symptom exists. In this exploratory re-analysis, we assessed whether administration of rapid-acting antidepressant ketamine was associated specifically with reduced anhedonia in medication-free treatment-refractory patients with major depressive...
Translational Psychiatry
October 14, 2014
Níall Lally, Allison C. Nugent, David A. Luckenbaugh et al.
269 citations
Anhedonia--which is defined as diminished pleasure from, or interest in, previously rewarding activities-is one of two cardinal symptoms of a major depressive episode. However, evidence suggests that standard treatments for depression do little to alleviate the symptoms of anhedonia and may cause reward blunting. Indeed, no therapeutics are currently approved for the treatment of anhedonia....
Current Biology
April 10, 2012
Jonathan P. Roiser, Geraint Rees
Two recent studies report changes in human brain responses after exposure to psilocybin, the active ingredient of hallucinogenic mushrooms. Psilocybin increased sensory cortex responses during emotional recollection, but decreased resting-state blood flow in prefrontal cortex, with potential implications for treating depression.
Journal of Psychopharmacology
May 30, 2008
L Clark, Jonathan P. Roiser, Trevor W Robbins et al.
Evidence for serotonin involvement in impulsivity has generated interest in the measurement of impulsivity in regular ecstasy users, who are thought to display serotonergic dysfunction. However, current findings are inconsistent. Here, we used a recently developed Information Sampling Test to measure 'reflection' impulsivity in 46 current ecstasy users, 14 subjects who used ecstasy in the past,...
Psychopharmacology
January 2007
Jonathan P. Roiser, Robert D Rogers, Barbara J. Sahakian
A number of studies have compared ecstasy users to control groups on various measures of neuropsychological function in order to determine whether ecstasy use results in lasting cognitive deficits. However, few of those studies controlled adequately for non-ecstasy illicit drug use. The aim of this study was to investigate neuropsychological function in chronic ecstasy users while controlling...
Psychopharmacology
October 2006
Jonathan P. Roiser, Robert D Rogers, Lynnette J Cook et al.
3, 4-Methylenedioxymethamphetamine (MDMA or "ecstasy") is a popular drug of abuse known to result in depletions of the serotonin (5-HT) system. A number of studies have reported that ecstasy users differ from controls on a variety of measures of cognitive function. However, the literature is not consistent and many negative findings were also reported. One reason for such inconsistency might be...
Psychopharmacology
May 2004
Jonathan P. Roiser, Barbara J. Sahakian
3,4-Methylenedioxymethamphetamine (MDMA or "ecstasy") causes serotonin neuron damage in laboratory animals. The serotonin system is known to be important in the regulation of mood. Previous research has shown that MDMA users score higher on self-report ratings of depression than controls. However, MDMA users commonly take other illicit substances and many studies do not fully control for...