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An increased prevalence of mixed-handedness has been reported in several neurodevelopmental and psychiatric disorders. Unfortunately, there is high between-study variability in the definition of mixed-handedness, leading to a major methodological problem in clinical laterality research and endangering replicability and comparability of research findings. Adding to this challenge is the fact that sometimes researchers use the concepts of mixed-handedness and ambidexterity interchangeably. Therefore, having a consensus on how to determine mixed-handedness and how to distinguish it from ambidexterity is crucial for clinical laterality research. To this end, hand preference and hand performance data from more than 600 participants from the Dortmund Vital Study (Trial registration: ClinicalTrials.gov NCT05155397), a population-based study in Germany, was analyzed to ascertain an optimal classification to determine mixed-handedness and ambidexterity. Using a combination of latent class analyses, effect size determination, and comparisons with the existing literature, we establish that an LQ cut-off criterion of +/−60 for mixed-handedness is optimal for future clinical laterality studies. Moreover, we show that mixed-handedness and ambidexterity are not identical and that the terms should not be used interchangeably. We further highlight the need for a consensus on how to mathematically determine ambidexterity as results of existing categorization schemes largely differ. Trial registration: ClinicalTrials.gov NCT05155397; . [ABSTRACT FROM AUTHOR]

While several studies have shown associations between hearing disorders and congenital toxoplasmosis, the present study investigated the impact of chronic, latent Toxoplasma gondii (T. gondii) infection on hearing loss. We used a regression analysis to explore whether latent T. gondii infection modulates changes in hearing thresholds over an age range from 20 to 70 years. We analyzed audiometric data of 162 T. gondii IgG-positive and 430 T. gondii-negative participants, collected in the Dortmund Vital Study (DVS, ClinicalTrials.gov Identifier: NCT05155397), a prospective study on healthy cognitive aging. The regression analysis indicated that latent toxoplasmosis was associated with an accelerated development in hearing loss over the observed age range. Hearing loss was less frequent in IgG-positive than in IgG-negative participants up to the age of about 40 for a low (0.125–1 kHz)-frequency range. For high (2–8 kHz) frequencies, this pattern reversed for ages above 65 years. We discuss these findings on hearing function in the context of a recently proposed model, suggesting that latent toxoplasmosis can differentially affect brain functions across a lifespan. [ABSTRACT FROM AUTHOR]

Even though the number of studies aiming to improve comprehension of ADHD pathology has increased in recent years, there still is an urgent need for more effective studies, particularly in understanding adult ADHD, both at preclinical and clinical levels, due to the increasing evidence that adult ADHD is highly distinct and a different entity from childhood ADHD. This review paper outlines the symptoms, diagnostics, and neurobiological mechanisms of ADHD, with emphasis on how adult ADHD could be different from childhood-onset. Data show a difference in the environmental, genetic, epigenetic, and brain structural changes, when combined, could greatly impact the behavioral presentations and the severity of ADHD in adults. Furthermore, a crucial aspect in the quest to fully understand this disorder could be through longitudinal analysis. In this way, we will determine if and how the pathology and pharmacology of ADHD change with age. This goal could revolutionize our understanding of the disorder and address the weaknesses in the current clinical classification systems, improving the characterization and validity of ADHD diagnosis, specifically those in adults. [ABSTRACT FROM AUTHOR]