Psychological Medicine
December 29, 2016
Rebecca Crane, Judson A. Brewer, Christina Feldman et al.
861 citations
A framework defines essential characteristics of mindfulness-based programs (MBPs) like MBSR and MBCT, distinguishing them from other interventions. MBPs draw from contemplative traditions, science, medicine, psychology, and education; are grounded in a model addressing causes of human distress and pathways to relief; foster present-moment focus, decentering, and an approach orientation; cultivate qualities such as joy, compassion, wisdom, equanimity, and self-regulation; and involve sustained intensive meditation training, experiential inquiry, and exercises. The framework aims to support clarity for systematic research and maintain integrity as MBPs expand into healthcare, education, criminal justice, and workplaces.
Psychological Medicine
June 15, 2018
Fernanda Palhano-Fontes, Dayanna Barreto, Heloisa Onias et al.
827 citations
A single dose of ayahuasca reduced depression severity more than placebo in patients with treatment-resistant depression. Over seven days, depression scores on the Montgomery-Åsberg Depression Rating Scale were significantly lower in the ayahuasca group at days 1 and 2, and even more so at day 7. Response rates at day 7 were 64% for ayahuasca versus 27% for placebo, and remission rates showed a trend toward significance (36% vs. 7%). Effect sizes grew from day 1 to day 7, indicating sustained improvement. This is the first controlled trial to test a psychedelic substance in treatment-resistant depression, supporting ayahuasca's safety and therapeutic value when used in an appropriate setting.
Psychological Medicine
November 27, 2009
A. Chiesa, A. Serretti
752 citations
Mindfulness meditation (MM) practices are linked to specific neurobiological changes and clinical benefits across psychiatric disorders, physical illnesses, and healthy individuals. Electroencephalographic studies show increased alpha and theta activity during meditation. Neuroimaging reveals activation of the prefrontal cortex and anterior cingulate cortex, with long-term practice enhancing attention-related brain areas. Clinically, Mindfulness-Based Stress Reduction benefits many conditions and healthy subjects; Mindfulness-Based Cognitive Therapy reduces depression relapse in patients with three or more episodes; Zen meditation lowers blood pressure; and Vipassana meditation reduces substance abuse in prisoners. However, low-quality study designs make it unclear whether benefits stem from specific or non-specific effects.
Psychological Medicine
February 12, 2016
Taishiro Kishimoto, J. M. Chawla, K. Hagi et al.
363 citations
A single intravenous infusion of ketamine reduces depression significantly more than placebo in people with major depressive disorder or bipolar depression, with effects beginning within 40 minutes, peaking at one day, and lasting up to one week. Non-ketamine NMDAR antagonists were superior to placebo only on days 5–8. Ketamine also led to greater response and remission rates at multiple time points. Adverse effects were transient and clinically insignificant, and discontinuation rates did not differ from placebo. The review analyzed 14 randomized controlled trials involving 588 participants.
Psychological Medicine
February 5, 2016
Robin Carhart‐Harris, Mendel Kaelen, Mark Bolstridge et al.
301 citations
A single intravenous dose of LSD (75 µg) in 20 healthy volunteers produced robust acute psychological effects, including heightened mood and elevated scores on a measure of psychosis-like symptoms. Two weeks later, participants showed increased optimism and trait openness compared to after placebo, with no changes in delusional thinking. The findings suggest that psychedelics can acutely induce psychosis-like symptoms yet improve psychological wellbeing in the mid to long term. The authors propose that acute mood changes stem from a more fundamental modulation of cognition, and that increased cognitive flexibility from serotonin 2A receptor stimulation promotes emotional lability during intoxication and leaves a lasting loosened cognition conducive to improved wellbeing.
Psychological Medicine
July 23, 2009
R. Martín-Santos, Ana B. Fagundo, José Alexandre S. Crippa et al.
207 citations
A systematic review of neuroimaging studies published up to January 2009 assessed evidence for cannabis effects on brain structure and function. Among 41 included studies, functional imaging indicated that resting global and prefrontal blood flow are lower in cannabis users than in controls. Activation studies during cognitive tasks produced inconsistent results. Acute administration of THC or marijuana increased resting activity and activation of the frontal and anterior cingulate cortex during cognitive tasks. Only three of eight structural imaging studies found differences between users and controls, providing minimal evidence of major effects of cannabis on brain structure.
Psychological Medicine
May 1, 2001
Sarajane Bhattachary, Jane H. Powell
138 citations
Recreational users of MDMA (ecstasy) show impaired verbal memory and verbal fluency compared to non-users, while visual memory and working memory remain unaffected. In a study comparing 80 participants divided into non-users, novice users, regular users, and currently abstinent users, all three MDMA-using groups performed significantly worse on tests of immediate and delayed prose recall and verbal fluency. The deficits were not explained by differences in general intelligence or cannabis use. Days since last use and total lifetime consumption of MDMA each independently contributed to the variance in recall scores, together accounting for nearly half the variance in delayed recall. The findings suggest that verbal memory impairments in MDMA users combine reversible acute effects that resolve over two to three weeks with longer-term changes linked to lifetime exposure.
Psychological Medicine
July 22, 2019
Fabrizio Schifano, Flavia Napoletano, Stefania Chiappini et al.
118 citations
A novel web-crawling tool called NPS.Finder® identified several thousand new psychoactive substances (NPS)—roughly four times more than European and international drug agencies report. Synthetic cannabinoids, new synthetic opioids, ketamine-like dissociatives, novel stimulants, novel psychedelics, and certain prescription and over-the-counter medicines were most commonly linked to psychopathological consequences. The rapid proliferation of recreational psychotropics poses a challenge for psychiatry because the pharmacodynamics and pharmacokinetics of many NPS remain poorly understood. Health and mental health professionals need up-to-date information on the range of NPS, their intake methods, sought-after effects, drug combinations, and associated medical and psychopathological risks.
Psychological Medicine
September 10, 2019
Thomas Pokorny, Patricia Duerler, Erich Seifritz et al.
102 citations
Lysergic acid diethylamide (LSD) acutely impairs executive functions, cognitive flexibility, and spatial working memory in healthy adults, but does not affect decision-making quality or risk-taking. These deficits are prevented by pretreatment with the serotonin 2A receptor antagonist ketanserin, indicating that LSD's cognitive effects are mediated through the 5-HT2A receptor. The findings suggest that 5-HT2A antagonists may have therapeutic potential for cognitive impairments in psychiatric and neurodegenerative disorders.
Psychological Medicine
March 18, 2020
Diego Quattrone, Laura Ferraro, Giada Tripoli et al.
89 citations
Daily use of high-potency cannabis is associated with more positive symptoms and fewer negative symptoms in first-episode psychosis patients. Among 901 patients and 1,235 controls across six European countries, those who used high-potency cannabis daily had the highest scores on positive symptoms, while negative symptoms were more common in patients who never used cannabis. Psychotic experiences in controls were linked to current cannabis use but not to lifetime use. Depressive symptoms showed no differences related to cannabis use in either group.
Psychological Medicine
January 28, 2004
Karen L. Hanson, Mónica Luciana
71 citations
People who used MDMA (ecstasy) and met criteria for substance abuse or dependence showed greater cognitive deficits than those who used the drug recreationally. MDMA users overall performed worse on memory and executive function tasks compared to non-users. The findings suggest that clinically dysfunctional MDMA use, rather than occasional recreational use, is linked to cognitive impairment.
Psychological Medicine
May 24, 2013
James Stone, Helen L. Fisher, Barnaby Major et al.
69 citations
Cannabis use is linked to an earlier onset of psychosis and more severe manic symptoms and conceptual disorganization, but not to delusions, hallucinations, negative symptoms, or daily functioning. In a naturalistic cohort of 502 patients with first-episode psychosis assessed at entry to services and after one year, those who reduced or stopped cannabis use showed the greatest improvement in symptoms, while continued users remained more symptomatic than non-users. Effective interventions to reduce cannabis use could yield significant health benefits for this population.
Psychological Medicine
September 1, 2008
G. Bedi, J. Redman
68 citations
Heavy ecstasy use is associated with some lowering of higher-level cognitive functions, but not with substantial cognitive dysfunction. A study comparing 45 abstinent ecstasy polydrug users, 48 cannabis polydrug users, and 40 legal drug users found no clear differences between groups on tests of attention, memory, and executive function. Lifetime dose of ecstasy was inversely linked to verbal memory performance, and a combination of drug-use variables, including ecstasy, predicted attention and working memory, though each factor explained only 1–6% of the variance in scores.
Psychological Medicine
November 4, 2020
Simon B. Goldberg, Benjamin Shechet, Christopher R. Nicholas et al.
66 citations
Classical psychedelics such as psilocybin, ayahuasca, and LSD produce significant psychological effects lasting at least 24 hours after administration, according to a systematic review and meta-analysis of 34 experimental studies involving 549 participants. Large effects were observed for reducing targeted symptoms in psychiatric samples, improving negative and positive affect, social outcomes, and existential or spiritual well-being, with between-group effect sizes ranging from Hedges' g = 0.84 to 1.08. Effects may be larger in clinical samples. Evidence for changes in personality traits or mindfulness was weak. No post-acute adverse effects were found, but high risk of bias, heterogeneity, and possible publication bias underscore the need for larger, placebo-controlled trials.
Psychological Medicine
October 2, 2017
André Schmidt, Felix Müller, Claudia Lenz et al.
62 citations
Activating the serotonin 2A receptor with LSD impairs the brain's ability to stop or inhibit responses, and this breakdown is linked to visual hallucinations. In a double-blind, placebo-controlled experiment with 18 healthy adults, LSD reduced brain activity in regions including the frontal and cingulate cortex, middle temporal gyrus, and cerebellum during a response-inhibition task. Parahippocampal activation related differently to performance under LSD versus placebo. Less activation in the left superior frontal gyrus during LSD exposure was associated with greater cognitive impairment and visual imagery. The findings suggest that 5-HT2A receptor activation disrupts hippocampal-prefrontal circuits, which may promote visual hallucinations.
Psychological Medicine
October 1, 2012
Zerrin Atakan, Sagnik Bhattacharyya, Paul Allen et al.
54 citations
A double-blind, placebo-controlled study of 21 healthy men with minimal cannabis experience found that oral administration of 10 mg THC induced transient psychotic symptoms in 11 participants but not in the other 10. Those who became transiently psychotic made more inhibition errors and showed opposite patterns of brain activation in the left parahippocampal gyrus, left and right middle temporal gyri, and right cerebellum compared to the non-psychotic group. The findings suggest that variability in sensitivity to THC's psychotogenic effects is linked to differential activation in ventral and medial temporal cortex and cerebellum.
Psychological Medicine
July 19, 2023
Tehseen Noorani, Gillinder Bedi, Suresh Muthukumaraswamy
49 citations
When a medical research program overlaps with a social movement, new forms of sociality—termed 'chemosociality'—emerge from shared chemical exposure. In psychedelic-assisted therapy (PAT) clinical trials, this chemosociality creates 'dark loops': unrecorded social interactions that breach assumptions underlying causal inference used to establish treatment efficacy. These loops affect participant experiences but are not incorporated into trial data interpretation. Three researcher responses are proposed: chemosocial minimization (designing trials to reduce dark loops), chemosocial description (openly documenting them), and chemosocial valorization (actively leveraging them for positive outcomes). The hype surrounding psychedelic research continues to shape the phenomena under study, even as trials grow larger and more rigorous.
Psychological Medicine
August 29, 2019
Jelle Lamsma, Wiepke Cahn, Seena Fazel et al.
48 citations
In people with psychotic disorders, daily use of cannabis, stimulants, and depressants significantly increases the odds of violent behavior, as does nondaily use of stimulants and hallucinogens. Daily cannabis use was associated with 1.6 times higher odds of violence, daily stimulant use with 2.8 times higher odds, and daily depressant use with 2.2 times higher odds. Nondaily stimulant use raised odds by 1.6 times, and nondaily hallucinogen use by 1.5 times. Daily hallucinogen use, analyzed only in the UK sample, increased odds 3.3-fold. The findings suggest that any substance use, not just daily use, should be targeted to prevent violence in this population.
Psychological Medicine
December 9, 2009
Jiřı́ Horáček, Martin Brunovský, Tomáš Novák et al.
42 citations
A single dose of ketamine (0.54 mg/kg infused over 30 minutes) rapidly alters brain electrical activity in healthy volunteers, producing a decrease in prefrontal theta cordance—a QEEG measure linked to cerebral blood flow—and an increase in central region theta cordance within 10 to 30 minutes. These changes resemble those seen after one week of treatment with standard antidepressants in people who respond to them, but occur much faster. The prefrontal theta cordance reduction correlated with ketamine and norketamine blood levels at 10 minutes. The findings suggest that theta cordance reduction could serve as a marker and predictor of ketamine's rapid antidepressant effect, a hypothesis warranting testing in depressed patients.
Psychological Medicine
August 25, 2017
Philip J. Cowen
38 citations
About 15% of depressed patients who do not respond to two antidepressant trials achieve remission with subsequent therapies. For treatment-resistant depression, augmentation with atypical antipsychotics quetiapine and aripiprazole has the strongest evidence, though lithium and triiodothyronine remain useful. Ketamine shows striking antidepressant effects in resistant depression, but developing similar glutamatergic drugs for continuous use is challenging. Growing understanding of inflammation's role in depression may allow repurposing anti-inflammatory agents and stratifying patients who would benefit. The dopamine agonist pramipexole, used carefully, could improve outcomes for refractory patients.
Psychological Medicine
February 1, 1977
R. Rodnight, R. M. Murray, M. C. H. Oon et al.
33 citations
Dimethyltryptamine (DMT) was detected in the urine of 47% of patients diagnosed with schizophrenia, 38% of those with other non-affective psychoses, 13% of those with affective psychoses, 19% of those with neurotic and personality disorders, and 5% of normal subjects. Operational definitions of psychosis did not identify any group more strongly associated with urinary DMT than a hospital diagnosis of schizophrenia. A discriminant function analysis of symptoms identified a group of 21 patients, of whom 71% excreted detectable DMT. A general relationship between psychotic symptoms and urinary DMT existed, but specifically schizophrenic symptoms were not major determinants of DMT excretion.
Psychological Medicine
April 28, 2020
Claire Mokrysz, Natacha D. C. Shaban, Tom P. Freeman et al.
24 citations
Inhaling cannabis reliably increases psychotic-like symptoms in healthy cannabis users and may raise the incidence of speech illusion—hearing words in meaningless white noise. Cannabidiol (CBD) did not blunt these effects. In one study, adults had stronger psychotic-like symptom responses than adolescents, suggesting adolescents may be less vulnerable to the acute psychotic-like effects of cannabis. The odds of experiencing speech illusion were 3.1 times higher after inhaling cannabis with THC and negligible CBD compared to placebo.
Psychological Medicine
November 1, 2012
E. M. Marks, C. Steel, E. R. Peters
20 citations
People who report unusual perceptual or belief experiences (anomalous experiences) but do not need clinical care are more prone to intrusive memories after watching a traumatic film than people with few such experiences. These intrusive memories are more vivid, emotional, and involuntary—resembling those seen in PTSD. The findings support the idea that a weak tendency to integrate information into its broader context may make some individuals vulnerable to intrusions, a symptom common to both PTSD and schizophrenia. A concurrent visuospatial task did not reduce intrusions in either group.
Psychological Medicine
December 7, 2020
Nicholas T. van Dam, Julieta Galante
19 citations
A critique of a recent study on harm after mindfulness-based stress reduction (MBSR) programs points out serious methodological limitations that undermine confidence in the authors' conclusion that MBSR is no more harmful than no treatment. The original study used a large observational dataset of 2,155 participants alongside active and wait-list arms of randomized controlled trials (156 and 118 participants respectively). The critique argues that despite the seemingly conclusive finding, the methods employed have potentially serious flaws.
Psychological Medicine
October 1, 2022
Wayne Hall, Keith Humphreys
18 citations
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