Cannabis consumption continues to be identified as a causal agent in the onset and development of psychosis. However, recent findings have shown that the effect of cannabis on psychosis may be moderated by childhood traumatic experiences. Using hierarchical multivariate logistic analyses the current study examined both the independent effect of cannabis consumption on psychosis diagnosis and...
BackgroundCannabis use is considered a component cause of psychotic illness, interacting with genetic and other environmental risk factors. Little is known, however, about these putative interactions. The present study investigated whether an urban environment plays a role in moderating the effects of adolescent cannabis use on psychosis risk.MethodProspective data (n=1923, aged 14–24 years at...
Background: An intrinsic cerebral network comprising the anterior cingulate and anterior insula (the salience network) is considered to play an important role in salience detection in healthy volunteers. Aberrant salience has been proposed as an important mechanism in the production of psychotic symptoms such as delusions and hallucinations (reality distortion). We investigated whether...
Psychotic symptoms have been linked to religious experience, but empirical evidence is scarce. We have investigated the impact of the Welsh religious revival (RR) of 1904-1905 on the number of admissions to the regional psychiatric hospital, their diagnostic features and lifelong course. All case-notes of patients admitted to the North Wales Hospital between 1902 and 1907 were included. There...
BACKGROUND: Theta cordance is a novel quantitative electroencephalography (QEEG) measure that correlates with cerebral perfusion. A series of clinical studies has demonstrated that the prefrontal theta cordance value decreases after 1 week of treatment in responders to antidepressants and that this effect precedes clinical improvement. Ketamine, a non-competitive antagonist of...
BACKGROUND: Mindfulness meditation (MM) practices constitute an important group of meditative practices that have received growing attention. The aim of the present paper was to systematically review current evidence on the neurobiological changes and clinical benefits related to MM practice in psychiatric disorders, in physical illnesses and in healthy subjects. METHOD: A literature search was...
Recent work suggests that heavy use of cannabis is associated with an increased risk of schizophrenia-like psychosis. However, there is a dearth of experimental studies of the effects of the constituents of cannabis, such as Delta9-tetrahydrocannabinol (THC). In a study of intravenous (i.v.) synthetic THC in healthy humans, we aimed to study the relationship of the psychotic symptoms induced by...
BACKGROUND: We conducted a systematic review to assess the evidence for specific effects of cannabis on brain structure and function. The review focuses on the cognitive changes associated with acute and chronic use of the drug. METHOD: We reviewed literature reporting neuroimaging studies of chronic or acute cannabis use published up until January 2009. The search was conducted using Medline,...
BackgroundEpidemiological evidence suggests a link between cannabis use and psychosis. A variety of factors have been proposed to mediate an individual's vulnerability to the harmful effects of the drug, one of which is their psychosis proneness. We hypothesized that highly psychosis-prone individuals would report more marked psychotic experiences under the acute influence of cannabis.MethodA...
The role of metacognitive beliefs in determining the impact of anomalous experiences: a comparison of help-seeking and non-help-seeking groups of people experiencing psychotic-like anomalies.
BackgroundAlthough there have been several reports linking ecstasy use with lowered cognitive function, much previous research suffers from substantial methodological limitations. The present study aimed to examine associations between ecstasy use and higher-level cognitive functions, using a larger sample size than most previous research and better controlling for a range of potential...
BackgroundThe relationship between cannabis use and psychosis is still a matter for debate. Accounting for the individual differences in subjective experiences to recreational cannabis use in the general population may hold some clues to the aetiological relationship between cannabis and psychotic symptoms. We hypothesized that schizotypy would account for the individual differences in...
Background: Functional imaging studies using working memory tasks have documented both prefrontal cortex (PFC) hypo- and hyperactivation in schizophrenia. However, these studies have often failed to consider the potential role of task-related deactivation. Method: Thirty-two patients with chronic schizophrenia and 32 age- and sex-matched normal controls underwent functional magnetic resonance...
Should we advise patients with serious mental illness to stop using cannabis?Advising patients with serious mental illness to stop their cannabis intake tends to be unpopular with patients, and also with some psychiatrists.Patients enjoy using cannabis, and can perceive it as being therapeutically beneficial.Thus, their reluctance to stop their cannabis intake is understandable.The argument of...
The aim was to examine the temporal relationships over 10 months between cannabis use and symptoms of psychosis and depression in people with schizophrenia and related disorders. The design was a prospective study of 101 patients with schizophrenia and related disorders who were assessed monthly over 10 months on medication compliance, cannabis and other drug use, symptoms of depression and...
A high proportion of people who have a serious mental illness also use non-prescribed psychoactive drugs. This association is perhaps most apparent, and possibly also has the greatest implications for health, in relation to tobacco use. In fact recognition of the special relationship between mental illness and smoking was recently reflected in exemption of psychiatric units from legislation to...
Background. Research suggests that low-grade psychotic experiences in the general population are a common but transitory developmental phenomenon. Using two independent general population samples, the hypothesis was examined that common, non-clinical developmental expression of psychosis may become abnormally persistent when synergistically combined with developmental exposures that may impact...
Background. Depersonalization has long been considered a syndrome but there is poor agreement on its constituent symptoms.Method. In order to establish whether different symptoms of depersonalization represent the expression of a single or several underlying dimensions, an exploratory factor analysis on the Cambridge Depersonalization Scale (CDS) was carried out on 138 consecutive patients...
Background. Use of MDMA (ecstasy), a serotonin neurotoxin, has been associated with memory impairment and psychological dysfunction. This study examined cognitive functioning in abstinent MDMA users and MDMA-naïve controls. Method. Participants completed measures of intelligence, motor function, attention, memory span, verbal fluency, immediate and delayed verbal memory, and working memory....
Background. Epidemiological findings suggest that cannabis use is a risk factor for the emergence of psychosis, and that the induction of psychotic symptoms in the context of cannabis use may be associated with a pre-existing vulnerability for psychosis. This study investigated in a non-clinical population the interaction between cannabis use and psychosis vulnerability in their effects on...