Midwakh/dokha tobacco use in the Middle East: much to learn.

Many alternative tobacco products (ATPs), such as hookahs, have grown in popularity and use beyond their locale of origin and are therefore becoming a significant global public health concern. This article provides an overview of an under-reported and understudied ATP, dokha, which is smoked in a midwakh pipe. It describes the state of tobacco control in the Arabian Gulf region where midwakh smoking appears to be most common, the history of midwakh and dokha use, and what is known about midwakh smoking from the published literature. On the basis of the stark lack of data on midwakh use, we suggest priority areas to focus future research. Preliminary data and observations from health providers and the public health sector suggest that midwakh smoking may pose challenges to the tobacco control efforts in the Arabian Gulf region. If it is emerging as a new ATP outside this region, there could be a significant impact on tobacco control strategies globally.

Abnormal prediction error is associated with negative and depressive symptoms in schizophrenia.

Prediction error in learning is where learning occurs to the degree to which an outcome consequent to a stimulus is surprising. It has been suggested that abnormal use of prediction error in schizophrenia may underlie the formation of inappropriate associations giving rise to psychotic symptoms. Kamin blocking is a phenomenon that demonstrates prediction error. Kamin blocking is shown where prior learning about a stimulus A paired with an outcome retards learning about a stimulus B when presented subsequently as part of a stimulus compound AB paired with the same outcome. Prior studies have indicated reduced Kamin blocking in schizophrenia specifically in non-paranoid patients. It is however unclear how reduced Kamin blocking is associated with specific symptoms in schizophrenia. The present study examined Kamin blocking performance in a high functioning community-based sample of 34 people with schizophrenia and 48 controls closely matched for pre-morbid IQ. In these patients we measured Kamin blocking and symptoms using positive and negative symptom scales (PANSS) and Scale for the Assessment of Negative Symptoms (SANS) and Scale for the Assessment of Positive Symptoms (SAPS). Results confirmed that people with schizophrenia had significantly reduced Kamin blocking. Kamin blocking performance was associated with negative and depressive symptoms. These associations with symptoms were crucially not found with baseline associative learning or unblocking measures, confirming specificity to the Kamin blocking effect. These data demonstrate first that abnormal prediction error as assessed in the Kamin blocking task is associated with negative and depressive symptoms rather than positive symptoms in high functioning schizophrenia patients. Second this strongly suggests that reduced Kamin blocking may be useful as an animal model of specific relevance to negative and depressive symptoms in schizophrenia.

An investigation into age and gender differences in human Kamin blocking, using a computerized task.

Kamin blocking (KB) is a function within selective attention found to be deficient in schizophrenia. Disparate results in the KB literature, specifically regarding age and gender effects, suggest that we do not yet have a comprehensive understanding of KB in normal human development. The aim of this study is to provide a thorough investigation into the development and occurrence of KB in a normal population. The design replicated and extended a study by Oades, Roepcke, and Schepker (1996). KB is measured using a computer game called the "mouse in the house." Participants must use a joystick to move an icon around a set floor plan, to find a hidden location. These locations are cued by sets of colors, which denote the KB paradigm. Data was collected on 222 participants across 5 age groups (6-8 years; 9-12 years; 13-17 years; 18-21 years; 22+ years). Comparisons were carried out for age and gender effects. KB was observed in all age groups, but there was no significant effect of age on mean KB score. A measure of frequency of participants who showed KB did show a significant increase with age. A significant difference was found between males and females, with females having higher KB score than males. The gender difference was present from the earliest age tested. Our findings suggest significant age and gender differences in the manifestation of selective attention and information processing abilities. This has implications for understanding the development of attention and the understanding of the age and gender dependence of the development of schizophrenia.