Inferring about individual drug and schizotypy effects on cognitive functioning in polydrug using mephedrone users before and after clubbing

Objective: Mephedrone has been recently made illegal in Europe, but little empirical evidence is available on its impact on human cognitive functions. We investigated acute and chronic effects of mephedrone consumption on drug-sensitive cognitive measures, while also accounting for the influence of associated additional drug use and personality features. Method: Twenty-six volunteers from the general population performed tasks measuring verbal learning, verbal fluency and cognitive flexibility before and after a potential drug-taking situation (pre- and post-clubbing at dance clubs, respectively). Participants also provided information on chronic and recent drug use, schizotypal (O-LIFE) and depressive symptoms (Beck depression inventory), sleep pattern and premorbid IQ. Results: We found that i) mephedrone users performed worse than non-users pre-clubbing, and deteriorated from the pre-clubbing to the post-clubbing assessment, ii) pre-clubbing cannabis and amphetamine (not mephedrone) use predicted relative cognitive attenuations, iii) post-clubbing, depression scores predicted relative cognitive attenuations, and iv) schizotypy was largely unrelated to cognitive functioning, apart from a negative relationship between cognitive disorganisation and verbal fluency. Conclusion: Results suggest that polydrug use and depressive symptoms in the general population negatively affect cognition. For schizotypy, only elevated cognitive disorganisation showed potential links to a pathological cognitive profile previously reported along the psychosis dimension.

An alternative method for dating unknown tephras based on a segmented regression model

In CoDaWork’05, we presented an application of discriminant function analysis (DFA) to 4 differentcompositional datasets and modelled the first canonical variable using a segmented regression modelsolely based on an observation about the scatter plots. In this paper, multiple linear regressions areapplied to different datasets to confirm the validity of our proposed model. In addition to dating theunknown tephras by calibration as discussed previously, another method of mapping the unknown tephrasinto samples of the reference set or missing samples in between consecutive reference samples isproposed. The application of these methodologies is demonstrated with both simulated and real datasets.This new proposed methodology provides an alternative, more acceptable approach for geologists as theirfocus is on mapping the unknown tephra with relevant eruptive events rather than estimating the age ofunknown tephra.Kew words: Tephrochronology; Segmented regression

Inter-informant agreement and prevalence estimates for mood syndromes: Direct interview vs. family history method.

BACKGROUND: The use of the family history method is recommended in family studies as a type of proxy interview of non-participating relatives. However, using different sources of information can result in bias as direct interviews may provide a higher likelihood of assigning diagnoses than family history reports. The aims of the present study were to: 1) compare diagnoses for threshold and subthreshold mood syndromes from interviews to those relying on information from relatives; 2) test the appropriateness of lowering the diagnostic threshold and combining multiple reports from the family history method to obtain comparable prevalence estimates to the interviews; 3) identify factors that influence the likelihood of agreement and reporting of disorders by informants. METHODS: Within a family study, 1621 informant-index subject pairs were identified. DSM-5 diagnoses from direct interviews of index subjects were compared to those derived from family history information provided by their first-degree relatives. RESULTS: 1) Inter-informant agreement was acceptable for Mania, but low for all other mood syndromes. 2) Except for Mania and subthreshold depression, the family history method provided significantly lower prevalence estimates. The gap improved for all other syndromes after lowering the threshold of the family history method. 3) Individuals who had a history of depression themselves were more likely to report depression in their relatives. LIMITATIONS: Low proportion of affected individuals for manic syndromes and lack of independence of data. CONCLUSIONS: The higher likelihood of reporting disorders by affected informants entails the risk of overestimation of the size of familial aggregation of depression.