8 papers in the library · 1,890 citations · publishing 2000-2012
PLoS ONE August 31, 2010 Erich Studerus, Alex Gamma, Franz X. Vollenweider 693 citations
The original OAV scales measured multidimensional constructs. Eleven new lower-order scales were developed and showed good psychometric properties. These new scales are probably better for assessing altered states of consciousness caused by drugs.
PLoS ONE February 17, 2012 Erich Studerus, Alex Gamma, Michael Kometer et al. 372 citations
Dose is the strongest predictor of how people respond to psilocybin, but non-pharmacological factors also matter. Among 409 administrations to 261 healthy volunteers, pleasant and mystical-type experiences were most strongly associated with high Absorption personality trait, emotional excitement and activity just before the drug, and few recent psychological problems. Unpleasant or anxious reactions were most strongly predicted by high Emotional Excitability, younger age, and undergoing a PET scan during the session. The findings confirm that personality, mood, and setting significantly shape psilocybin's effects, though dose remains the dominant factor.
Psychopharmacology March 5, 2001 Matthias E. Liechti, Alex Gamma, Franz X. Vollenweider 357 citations
Equal doses of MDMA per kilogram of body weight produce stronger subjective effects in women than in men. Women reported more intense perceptual changes, thought disturbances, and fear of losing body control, and they experienced more acute adverse effects and aftereffects. The dose of MDMA correlated with the intensity of perceptual changes in women. Men showed greater increases in blood pressure. These findings suggest women may be more susceptible to the serotonin-releasing effects of MDMA.
Human Brain Mapping August 27, 2001 Edi Frei, Alex Gamma, Roberto D. Pascual‐marqui et al. 175 citations
A single dose of MDMA (1.7 mg/kg) in 16 healthy, MDMA-naïve volunteers produced widespread decreases in slow and medium frequency brain activity and increases in fast frequency activity in the anterior temporal and posterior orbital cortex, as measured by scalp EEG and low resolution brain electromagnetic tomography (LORETA). These changes were accompanied by heightened mood, emotional arousal, and increased extraversion. The EEG pattern suggests that serotonin, noradrenaline, and, to a lesser degree, dopamine contribute to MDMA's effects on brain activity and possibly mood and behavior, indicating modulation of limbic orbitofrontal and anterotemporal structures involved in emotional processes.
Journal of Psychoactive Drugs June 1, 2002 Franz X. Vollenweider, Matthias E. Liechti, Alex Gamma et al. 92 citations
Since the mid 1990s, MDMA has been increasingly used recreationally as 'Ecstasy' by young people in Europe and the United States, yet systematic data on its psychological and neurobiological effects have been scarce. The authors conducted several studies in healthy human volunteers using placebo-controlled within-subject designs, standardized psychometric ratings, and neuropsychological tests to characterize the acute, short-term, and prolonged effects of MDMA. They also used specific receptor antagonists and Positron Emission Tomography to explore the neurotransmitter systems and functional neuroanatomy involved. This summary covers MDMA's acute effects on psychological and cognitive measures, information processing, and regional brain activity in healthy volunteers.
Journal of Clinical Psychopharmacology February 1, 2001 Alex Gamma, Alfred Buck, Thomas Berthold et al. 84 citations
Regular polytoxic Ecstasy users show higher levels of depressiveness than non-users, but their brain activity during a sustained-attention task does not differ from controls. Mood was assessed with the Hamilton Rating Scale for Depression and the EWL Mood Rating Scale, while regional cerebral blood flow was measured using positron emission tomography. Both groups performed equally on the cognitive task. The heightened depressiveness in Ecstasy users is consistent with previous studies and may relate to serotonergic hypofunction from repeated MDMA consumption, but the study cannot rule out that these mood differences existed before Ecstasy use.
Neuroreport January 1, 2000 Alex Gamma, Edi Frei, Dietrich Lehmann et al. 81 citations
People who regularly use Ecstasy show altered brain activity patterns, including increased theta, alpha, and beta power across the scalp, particularly with eyes open, as measured by EEG and brain tomography. They also report higher levels of state depressiveness, emotional excitability, and a trend toward increased state anxiety compared to non-users. These differences could stem from regular Ecstasy or other illicit drug use, or may have existed before drug use began.
Journal of Psychopharmacology September 1, 2005 Alex Gamma, Daniel Brandeis, Ruven Brandeis et al. 36 citations
People who use ecstasy (MDMA) along with other drugs show reduced P3 brain-wave amplitudes during a task that requires inhibiting a prepared response, compared with non-users. This lower amplitude is consistent with greater neural disinhibition. However, the normal pattern of brain activity shifting forward when inhibiting a response, and the less frontal location of the inhibition-related brain signal, do not point to a fundamental disruption of inhibitory brain mechanisms. The differences became weaker after accounting for age, education, and lifetime cannabis use.