Network Meta-Analysis for Single-Case Design Studies: An Illustration.

Single-case designs (SCDs) are used to evaluate the effects of interventions on individual participants. By repeatedly measuring participants under different conditions, SCD studies focus on individual effects rather than on group summaries. The main limitation of SCDs remains its generalisability to wider populations, reducing the relevance of their findings for practice and policy making. With this limitation in mind, methodological developments for synthesising SCD data from different studies that investigate the same research question have intensified in the past decades (e.g. multilevel modelling). However, these techniques are restricted to comparing two interventions at a time and can only incorporate evidence from studies that directly compare the two treatments of interest. These limitations could be addressed by using network meta-analysis that incorporates both direct and indirect evidence to simultaneously compare multiple interventions. Despite its potential, network meta-analytical techniques have yet to be applied to SCD data. Thus, in this paper, we argue that network meta-analysis can be a valuable tool to synthesise SCD data. We demonstrate the use of network meta-analysis in SCD data using a real dataset, and we conclude by reflecting on the challenges that SCD researchers might face when applying network meta-analysis methods to their data.

A decade of theory as reflected in Psychological Science (2009-2019).

The dominant belief is that science progresses by testing theories and moving towards theoretical consensus. While it's implicitly assumed that psychology operates in this manner, critical discussions claim that the field suffers from a lack of cumulative theory. To examine this paradox, we analysed research published in Psychological Science from 2009-2019 (N = 2,225). We found mention of 359 theories in-text, most were referred to only once. Only 53.66% of all manuscripts included the word theory, and only 15.33% explicitly claimed to test predictions derived from theories. We interpret this to suggest that the majority of research published in this flagship journal is not driven by theory, nor can it be contributing to cumulative theory building. These data provide insight into the kinds of research psychologists are conducting and raises questions about the role of theory in the psychological sciences.

Sexual behaviour in a murine model of mucopolysaccharidosis type I (MPS I).

Mucopolysaccharidosis Type I (MPS I) is a rare genetic lysosomal storage disease caused by a mutation of IDUA gene. IDUA codes for α-L-iduronidase (IDUA), a lysosomal hydrolase that degrades glycosaminoglycans (GAGs): heparan sulphate and dermatan sulphate. GAGs are structural and signalling molecules that have a crucial role in controlling a variety of cell functions and their interaction with the extracellular matrix. Because of GAG's widespread action in cellular metabolism, MPS I is a progressive and disabling multisystemic disorder. Nowadays, the therapies available allowed patients to reach the adult life and the consequences of the disease in their reproductive system are mostly unknown. We aimed to investigate whether IDUA disruption influences sexual behaviour and sexual steroid production in male and female MPS I mice. We used 3 and 6-month-old male and 3-month-old female Idua+/_ and Idua-/- mice to evaluate typical rodent copulatory behaviours. In males we observed the frequency and latency of mounts, intromissions and ejaculations. In females, we evaluated the lordosis quotient. We also analysed the locomotor capacity of mice in the open field test, since mobility is essential for copulatory behaviour. We also quantified steroidal hormonal levels in plasmatic samples. We detected an increase in the latencies of intromissions in Idua-/- males when compared to Idua+/_. However, the number of intromissions was not statistically different between groups. No parameter of female sexual behaviour was statistically different between control and knockout females. In both sexes, we detected diminished mobility in Idua-/- mice. Plasma hormone levels did not differ between Idua+/_ and Idua-/- mice, both in males and females. Although the motor disability predicted to MPS I animals, we concluded that in the considered time point of MPS I progression studied, mice are able to perform sexual behaviour.