Schizophrenia Research
August 25, 2022
Olga Santesteban-Echarri, Lu Liu, Madeline Miller et al.
Youth at clinical high-risk for psychosis report more lifetime, past-six-month, and baseline cannabis use than healthy controls, along with greater frequency, severity, and rates of cannabis use disorder. Among high-risk youth, those who use cannabis show higher baseline grandiosity and lower social anhedonia at 12 months. Cannabis use severity was unrelated to clinical status at two years and did not distinguish those who later developed psychosis from those who did not. The small number of cannabis users in the high-risk group limited statistical power.
Schizophrenia Research
May 1, 2022
Andreas Rosén Rasmussen, Josef Parnas
Obsessive-compulsive symptoms are common in schizophrenia-spectrum disorders and can complicate diagnosis, especially in first-contact patients. Classic psychopathology defines true obsessions in obsessive-compulsive disorder (OCD) as intrusions with intact resistance and insight, while in schizophrenia, pseudo-obsessive-compulsive phenomena lack resistance and align with thought disorder or catatonia. Current diagnostic systems use broader, vaguer definitions, causing overlap with delusions and other anomalies. The authors examine links between obsessive-compulsive phenomena and disturbances of basic experience in schizophrenia-spectrum disorders, suggesting these experiential alterations aid differential diagnosis and early detection.
Schizophrenia Research
September 9, 2021
T. J. Tao, C. Hui, Bertha S. T. Lam et al.
Mindfulness meditation improves a range of outcomes for Chinese patients with psychosis, most consistently and sustainably for insight, rehospitalization duration, recovery rate, and social functioning. Evidence from 23 articles (20 studies) involving 1749 patients showed that age and duration of illness, but not total intervention hours, moderated overall efficacy. Post-meditation improvements in mindfulness were related to improvements in clinical and well-being outcomes. The effects may be driven by promoting positive personal growth and enhancing coping with illness and symptoms. Results should be considered in light of varying study quality and heterogeneity; further research is needed on sustainability, active ingredients, mechanisms, and additional moderators.
Schizophrenia Research
July 1, 2020
Timo Hennig, Björn Schlier, Tania M Lincoln
Shorter sleep time and negative dream valence predict paranoid symptoms, while feeling less rested and recalling dreams predict hallucinatory experiences. In people with elevated psychosis proneness, these sleep-related effects on hallucinations are stronger. The relationship between poor sleep and paranoia is bidirectional, but poor sleep only predicts hallucinations, not the reverse. The findings highlight sleep disturbance as a contributor to psychotic experiences and suggest that improving sleep could help prevent such symptoms.
Schizophrenia Research
August 1, 2018
L Stan Leung, Jingyi Ma
In an animal model of schizophrenia induced by NMDA receptor antagonists like phencyclidine, MK-801, and ketamine, the septohippocampal system plays a key role. These drugs cause behavioral and electrophysiological disruptions, including reduced prepulse inhibition of the acoustic startle response, hyperlocomotion, impaired auditory gating, and increased hippocampal gamma oscillations. A single hippocampal seizure produces similar effects. Inactivating or lesioning GABAergic neurons in the medial septum, deep brain stimulation of the medial septum or nucleus accumbens, or positive modulation of GABAB receptors can reduce these disruptions. The findings indicate a close link between high-amplitude hippocampal gamma oscillations and psychosis-relevant behaviors, suggesting the hippocampus acts as a hub in a brain network underlying these symptoms.
Schizophrenia Research
April 1, 2018
Susan Whitfield-Gabrieli, Adina S Fischer, Angela Henricks et al.
In a pilot study, patients with schizophrenia and cannabis use disorder showed over-connectivity in the default mode network (DMN) at rest, which correlated with more severe positive symptoms, and reduced anticorrelation between the DMN and the executive control network (ECN). After smoking a 3.6% THC cannabis cigarette or ingesting a 15 mg THC pill, DMN hyperconnectivity decreased and DMN-ECN anticorrelation increased. The degree of anticorrelation in healthy controls and in patients after cannabinoid administration positively correlated with working memory performance. The results suggest that DMN connectivity can change, which may inform future treatments targeting circuit-level dysfunction.
Schizophrenia Research
November 1, 2016
David A Cox, Michael G Gottschalk, Hendrik Wesseling et al.
A systems biology approach compared protein changes in anterior prefrontal cortex tissue from four glutamatergic rodent models of schizophrenia and from human post-mortem schizophrenia patients. Liquid chromatography-tandem mass spectrometry proteomic profiling identified five functional domains of the disease, including "development and differentiation," represented across all rodent models. Kernel-based machine learning quantified that the chronic phencyclidine (PCP) model most closely resembled schizophrenia brain changes for four of these domains. The authors argue this methodology helps evaluate which rodent model best recapitulates neuropathological features of schizophrenia, supporting efforts to link functional behavioral dimensions with distinct biological processes.
Schizophrenia Research
May 1, 2015
T. Winton-Brown, V. Kumari, F. Windler et al.
Sensorimotor gating—measured by how a quieter sound modifies the eye-blink startle reflex to a loud noise—is altered in people with psychosis, their relatives, and those at high clinical risk. Cannabis use also alters gating, though less strongly, and is a known risk factor for psychosis in susceptible individuals. This study tested prepulse inhibition (PPI) and prepulse facilitation (PPF) in participants with an At Risk Mental State (ARMS) for psychosis and matched controls, some of whom had recently used cannabis (confirmed by urine drug screening). ARMS participants showed reduced PPF and PPI compared to controls; the PPI reduction was driven by an interaction with cannabis use, where recent use reduced PPI only in ARMS participants.
Schizophrenia Research
July 1, 2011
David P Johnson, David L Penn, Barbara L. Fredrickson et al.
Loving-kindness meditation was feasible for people with schizophrenia-spectrum disorders who had significant negative symptoms. Participation was associated with decreased negative symptoms and increased positive emotions and psychological recovery.
Schizophrenia Research
July 1, 2009
Félix-Antoine Lusignan, Antonio Zadra, Marie-Josée Dubuc et al.
People with schizophrenia report more nightmares than healthy controls, but their overall dream recall, recurrent dreams, and emotional frequency are similar. When dreams are collected in a sleep laboratory, patients' narratives are shorter; after adjusting for length, most content differences disappear except for a higher proportion of unknown characters. Patients rate their own dreams as less bizarre than controls do, even though external judges see similar bizarreness. Eye movement density during REM sleep is comparable between groups, but a link between eye movements and dream content appears only in controls. These patterns suggest that dream content in schizophrenia may reflect disorder-specific neurocognitive processes, particularly emotional processing.
Schizophrenia Research
December 1, 2006
Dagmar Koethe, Christoph W Gerth, Miriam A Neatby et al.
In people with schizophrenia, in the prodromal phase, and in healthy volunteers given synthetic delta-9-tetrahydrocannabinol (THC), performance on a test of visual information processing (the Binocular Depth Inversion Illusion Test) was similarly impaired, and all three groups differed significantly from healthy controls who received no drug. On the Brief Psychiatric Rating Scale, the THC-treated group and the prodromal group did not differ significantly, while both differed from the schizophrenia group and from controls. The findings suggest that THC-induced altered states can model psychotic disorders, especially their prodromal states, and help explain the pro-psychotic effects of high-THC cannabis.
Schizophrenia Research
November 15, 2005
Robert F Ferdinand, Jan Van der Ende, Ilja Bongers et al.
Cannabis use is specifically linked to later psychotic symptoms, independent of earlier psychopathology. A 14-year follow-up of 1,580 Dutch children initially aged 4 to 16 found that the association between cannabis use and psychotic symptoms remained after accounting for prior behavioral and emotional problems. The study used survival analyses and suggests cannabis use is a specific risk factor for future psychotic symptoms, not merely a consequence of prior mental health issues. This supports prevention efforts targeting cannabis use to potentially reduce psychotic symptoms in vulnerable individuals.
Schizophrenia Research
March 1, 2005
Lindsay M Reynolds, Susan M Cochran, Brian J Morris et al.
Repeated intermittent doses of phencyclidine (PCP) in rats caused deficits of N-acetylaspartate (NAA) and its precursor N-acetylaspartylglutamate (NAAG) specifically in the temporal cortex, while NAAG was elevated in the hippocampus. These changes mirror postmortem findings in schizophrenia, supporting the use of PCP-treated rats as a model for the neuronal dysfunction seen in that disease.
Schizophrenia Research
September 1, 1994
P K McGuire, P Jones, I Harvey et al.
Psychotic patients who tested positive for cannabis and those who did not were indistinguishable in their psychopathology, diagnoses, illness onset, and demographic backgrounds. The only difference was in substance use history. This suggests that psychosis occurring alongside cannabis use does not have a distinctive presentation or onset pattern and is not limited to any specific ethnic or socioeconomic group, offering little support for 'cannabis psychosis' as a separate diagnostic category.