The finding that people with a first episode of psychosis had smoked higher-potency cannabis, for longer and with greater frequency, than a healthy control group is consistent with the hypothesis that Delta 9-THC is the active ingredient increasing risk of psychosis. This has important public health implications, given the increased availability and use of high-potency cannabis.

Both cannabis use and the dopamine receptor (DRD2) gene have been associated with schizophrenia, psychosis-like experiences, and cognition. However, there are no published data investigating whether genetically determined variation in DRD2 dopaminergic signaling might play a role in individual susceptibility to cannabis-associated psychosis. We genotyped (1) a case-control study of 272 patients with their first episode of psychosis and 234 controls, and also from (2) a sample of 252 healthy subjects, for functional variation in DRD2, rs1076560. Data on history of cannabis use were collected on all the studied subjects by administering the Cannabis Experience Questionnaire. In the healthy subjects' sample, we also collected data on schizotypy and cognitive performance using the Schizotypal Personality Questionnaire and the N-back working memory task. In the case-control study, we found a significant interaction between the rs1076560 DRD2 genotype and cannabis use in influencing the likelihood of a psychotic disorder. Among cannabis users, carriers of the DRD2, rs1076560, T allele showed a 3-fold increased probability to suffer a psychotic disorder compared with GG carriers (OR = 3.07; 95% confidence interval [CI]: 1.22-7.63). Among daily users, T carrying subjects showed a 5-fold increase in the odds of psychosis compared to GG carriers (OR = 4.82; 95% CI: 1.39-16.71). Among the healthy subjects, T carrying cannabis users had increased schizotypy compared with T carrying cannabis-naïve subjects, GG cannabis users, and GG cannabis-naïve subjects (all P ≤ .025). T carrying cannabis users had reduced working memory accuracy compared with the other groups (all P ≤ .008). Thus, variation of the DRD2, rs1076560, genotype may modulate the psychosis-inducing effect of cannabis use.

The catechol-O-methyltransferase (COMT) val(158)met single nucleotide polymorphism (rs4680) has been shown to be associated with brain activation during a number of neurocognitive and emotional tasks. The present study evaluated genotypic associations with brain function during measurement of cognitive stability (prosaccades) and plasticity (antisaccades). A total of 36 healthy volunteers were genotyped for rs4680 and underwent functional magnetic resonance imaging (fMRI) at 1.5 T. Individuals with at least one val(158) allele (val(158) carriers, N=24) showed lower blood oxygen level-dependent (BOLD) response in ventromedial and dorsomedial prefrontal cortex during antisaccades compared to val(158) noncarriers, whereas met(158) homozygotes (N=12) showed lower BOLD response in a cluster in the posterior cingulate and precuneus during prosaccades compared to val(158) carriers. These findings suggest that associations of COMT val(158)met genotype with brain function may be mediated by task characteristics. The findings may be compatible with a hypothesis on the role of COMT val(158)met genotype in tonic and phasic dopamine levels in brain and differential effects on cognitive measures of stability (eg prosaccades) and plasticity (eg antisaccades).

Background. Many studies have reported that cannabis use increases the risk of a first episode of psychosis (FEP). However, only a few studies have investigated the nature of cannabis-related experiences in FEP patients, and none has examined whether these experiences are similar in FEP and general populations. The aim of this study was to explore differences in self-reported cannabis experiences between FEP and non-psychotic populations.Method. A total of 252 subjects, who met International Classification of Diseases (ICD)-10 criteria for FEP, and 217 controls who reported cannabis use were selected from the Genetics and Psychosis (GAP) study. The Medical Research Council Social Schedule and the Cannabis Experience Questionnaire were used to collect sociodemographic data and cannabis use information, respectively.Results. Both 'bad' and 'enjoyable' experiences were more commonly reported by FEP subjects than controls. Principal components factor analysis identified four components which explained 62.3% of the variance. Linear regression analysis on the whole sample showed that the type of cannabis used and beliefs about the effect of cannabis on health all contributed to determining the intensity and frequency of experiences. Linear regression analysis on FEP subjects showed that the duration of cannabis use and amount of money spent on cannabis were strongly related to the intensity and frequency of enjoyable experiences in this population.Conclusions. These results suggest a higher sensitivity to cannabis effects among people who have suffered their first psychotic episode; this hypersensitivity results in them reporting both more 'bad' and 'enjoyable' experiences. The greater enjoyment experienced may provide an explanation of why FEP patients are more likely to use cannabis and to continue to use it despite experiencing an exacerbation of their psychotic symptoms.

Cannabis use has increased greatly over the last three decades. The various types of cannabis differ in their concentration of the main psychoactive component, Delta-9-tetrahydrocannabinol (THC), and the other major ingredient, cannabidiol (CBD). Plant engineering has maximized levels of THC, thus increasing the potency of street cannabis. It is well known that cannabis intoxication can cause brief psychotic symptoms like paranoia, whilst recent evidence demonstrates that heavy use of cannabis increases the risk of chronic psychoses like schizophrenia; genetic vulnerability seems to predispose some people to a higher risk. This paper starts to consider the neurochemical mechanisms whereby cannabis use increases the risk of psychosis.

Introdução: O bebê prematuro é considerado de alto risco para atrasos no desenvolvimento, uma vez que está exposto a fatores biológicos e/ou ambientais, muitas vezes, pouco congruentes com sua maturidade neurobiológica. Objetivo: Descrever o perfil sensorial, identificar as respostas aos estímulos sensoriais e  os padrões sensoriais de  crianças pequenas com histórico de prematuridade. Método: Estudo exploratório-descritivo, realizado com  43 pais de crianças com idade entre 7 e 35 meses, que apresentaram histórico de prematuridade com ou sem comorbidades, utilizando um  roteiro semiestruturado, elaborado pelas pesquisadoras, com perguntas relacionadas à história pregressa e atual dos bebês e de seus pais; e o Toddler Sensory Profile 2, que auxilia na determinação das repostas sensoriais  e delineia o padrão do perfil sensorial de crianças com idade entre 7 e 35 meses. Resultados:  A maioria das crianças era do sexo masculino (53,5%) e menores de 18 meses de idade corrigida (69,7%). As maiores frequências de respostas foram classificadas como a maioria das crianças nas áreas sensoriais dos processamentos: geral (55,8%), auditivo (41,9%), visual (60,5%), tátil (51,2%), do movimento (39,5%), oral (58,1%) e nas respostas comportamentais associadas (41,9%). O mesmo ocorreu referente aos quadrantes em procura (69,7%); evita (51,2%); sensibilidade (46,5%); e registro (60,5%) Conclusão: Os resultados demonstram que a maioria das crianças pequenas avaliadas apresenta respostas dentro do esperado em todas as áreas sensoriais e nos quadrantes, entretanto, algumas apresentaram alterações de repostas (hiper ou hipo), o que justifica a importância do rastreio sensorial em crianças pequenas com histórico de prematuridade para acompanhamento precoce.Palavras-chave: Desenvolvimento infantil; Processamento sensorial; Bebê prematuro Abstract Introduction: The baby prematurely is considered at risk for developmental delays since it is exposed to biological and/or environmental factors that are often not congruent with its neurobiological maturity. Objective: To identify and to describe the responses to sensory stimuli and the sensory patterns of young children with a history of prematurity. Method: Exploratory-descriptive study, carried out with 43 parents of children aged between 7 and 35 months who had a history of prematurity with or without comorbidities. It was used a semi-structured questionnaire, prepared by the researchers, with questions related to the past and current history of the children and their parents; and the Toddler Sensory Profile 2, which helps to determine sensory responses and outlines the pattern of the sensory profile of children aged 7 to 35 months. Results: Most children were male (53.5%) and younger than 18 months corrected age (69.7%). The highest frequencies of responses were classified just like the majority of children in the sensory areas: general processing (55.8%), auditory (41.9%), visual (60.5%), tactile (51.2%), movement (39.5%), oral (58.1%) and associated behavioral responses (41.9%). The same occurred regarding the quadrants in seeking (69.7%); avoiding (51.2%); sensitivity (46.5%) and registration (60.5. Conclusion: The results demonstrate that most of the young children evaluated presented responses within the expected in all sensory areas and in the quadrants, however, some of them presented alterations in responses (hyper or hypo). This fact justify the needs of sensory screening and early intervention for young children with a history of prematurity.Keywords: Occupational Therapy. Cognition. Memory. Personal Narrative. Life Experience ResumenIntroducción: El bebé prematuro es considerado de alto riesgo para retrasos en el desarrollo, ya que están expuestos a factores biológicos y/o ambientales que muchas veces son incongruentes con su madurez neurobiológica. Objetivo Describir el perfil sensorial, identificar respuestas a estímulos sensoriales y patrones sensoriales de niños pequeños con antecedentes de prematuridad. Método: Estudio exploratorio-descriptivo, realizado con 43 padres de niños de 7 a 35 meses de edad con antecedentes de prematuridad con o sin comorbilidades, utilizando un guión semiestructurado elaborado por las investigadoras con preguntas relacionadas con la historia pasada y actual de los bebés y sus padres; y el Toddler Sensory Profile 2, que ayuda a determinar las respuestas sensoriales y describe el patrón del perfil sensorial de los niños de entre 7 y 35 meses. Resultados: La mayoría de los niños eran del sexo masculino (53.5%) y menores de 18 meses de edad corregida (69.7%). Las mayores frecuencias de respuestas se clasificaron como la mayoría de los niños en las áreas sensoriales de procesamiento: general (55.8 %), auditiva (41.9 %), visual (60.5 %), táctil (51.2 %), de movimiento (39.5 %), oral (58.1 %) y en las respuestas comportamentales asociadas (41.9%). Lo mismo ocurrió respecto a los cuadrantes de búsqueda (69.7%); evitar (51.2%); sensibilidad (46.5%) y registro (60.5%). Conclusión: Los resultados demuestran que la mayoría de los niños pequeños evaluados presentaron respuestas dentro de lo esperado en todas las áreas sensoriales y en los cuadrantes, sin embargo, algunos mostraron alteraciones en las respuestas (hiper o hipo), lo que justifica la importancia del tamizaje sensorial en niños pequeños con antecedentes de prematuridad, para un acompañamiento temprano.Palabras clave: Desarrollo infantil; Procesamiento sensorial; Bebé prematuro

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Background:Epidemiological studies have reported that the increased risk of developing psychosis in cannabis users is dose related. In addition, experimental research has shown that the active constituent of cannabis responsible for its psychotogenic effect is Delta-9-Tetrahydrocannabinol (THC) (Murray et al, 2007). Recent evidence has suggested an increased in potency (% TCH) in the cannabis seized in the UK (Potter et al, 2007).Hypothesis:We predicted that first episode psychosis patients are more likely to use higher potency cannabis and more frequently than controls.Methods:We collected information concerning socio-demographic, clinical characteristics and cannabis use (age at first use, frequency, length of use, type of cannabis used) from a sample of 191 first-episode psychosis patients and 120 matched healthy volunteers. All were recruited as part of the Genetic and Psychosis (GAP) study which studied all patients who presented to the South London and Maudsley Trust.Results:There was no significant difference in the life-time prevalence of cannabis use or age at first use between cases and controls. However, cases were more likely to be regular users (p=0.05), to be current users (p=0.04) and to have smoked cannabis for longer (p=0.01). Among cannabis users, 86.8% of 1st Episode Psychosis Patients preferentially used Skunk/Sinsemilla compared to 27.7% of Controls. Only 13.2 % of 1st Episode psychosis Patients chose to use Resin/Hash compared to 76.3% of controls. The concentration of TCH in these in South East London, ranges between 8.5 and 14 % (Potter et al, 2007). Controls (47%) were more likely to use Hash (Resin) whose average TCH concentration is 3.4% (Potter et al, 2007).Conclusions:Patients with first episode psychosis have smoked higher potency cannabis, for longer and with greater frequency, than healthy controls.