Database of 25 validated coil models for electric field simulations for TMS.

BACKGROUND: The effects of transcranial magnetic stimulation (TMS) on brain activity depend on the design of the stimulation coil. A wide range of coils from different vendors are currently used with different stimulation properties. This decreases the comparability of study results. OBJECTIVE: To systematically compare widely used commercial TMS coils concerning their focality, stimulation depth and efficacy. To provide validated models and data of these coils for accurate simulations of the induced electric fields. METHODS: We reconstructed the magnetic vector potential of 25 commercially available TMS coils of different vendors from measurements of their magnetic fields. Most coils had a figure-of-eight configuration. We employed the reconstructed magnetic vector potential in simulations of the electric field in a spherical head model. We estimated the motor thresholds of the coil-stimulator combinations using the calculated fields, the pulse waveforms and a leaky integrator model of the neural membrane. RESULTS: Our results confirm a previously reported systematic trade-off between focality and relative depth of stimulation. However, neither the peak field strength in the "cortex" of the sphere model nor the estimated motor thresholds were strongly related to the two former measures and need to be additionally determined. CONCLUSION: Our comprehensive coil characterization facilitates objective comparisons of coils of different sizes and from different vendors. The models and auxiliary data will be made available for electric field simulations in SimNIBS. Our work will support TMS users making an informed selection of a suited coil for a specific application and will help to reduce uncertainty regarding the TMS-induced electric field in the brain target region.

NEET status among young Greeks: Association with mental health and substance use.

BACKGROUND: Prior studies have shown that young people "not in education, employment or training" ("NEET") are at higher risk for psychopathology and substance abuse. Similar studies are lacking in Southern European populations. We aimed to examine the associations of anxiety and depressive symptoms, and substance use with NEET status in a large, randomized population-based sample in Greece. METHODS: A telephone structured questionnaire was conducted in a representative sample of 2771 young Greeks aged 15-24 years. Anxiety and depressive symptoms were assessed with GAD-7 and PHQ-9 scales, respectively. Substances use and several sociodemographic parameters were also examined. RESULTS: In our sample 16.4% were NEETs. In multivariate analyses, NEETs compared to non-NEETs were older, with lower family income, without insurance and more likely to be married and smoke. Furthermore, NEET status was associated with a higher GAD-7 score among older NEETs and long-term NEETs (NEETs unemployed for more than a year). Moreover, being NEET among older participants was associated with severe symptoms of anxiety and moderate/severe symptoms of depression. LIMITATIONS: This was a telephone survey and a clinical evaluation of the patients was not performed. Furthermore, the structured interview was not designed to detect the level of substance use or the reasons for being NEET. CONCLUSIONS: NEET status is frequent among young Greeks. Older, and long-term NEETs appear to be at higher risk for presenting anxiety/depression symptoms. Whether NEET status is associated with adverse outcomes later in life requires longitudinal studies.