Back muscles activity and scoliosis in ataxic and dystrophic patients

To investigate the role of muscles in the development of adolescent idiopathic scoliosis (AIS), our group was initially interested in Duchenne muscular dystrophy (DMD) diseases where a muscular degeneration often leads to scoliosis. Few years ago the studies with those patients provided interesting results but were obtained only from few patients. To increase that number, the present project was initiated but recruitment of new DMD patients from Marie-Enfant hospital was found impossible. As an alternative, patients with Friedreich’s ataxia (FA) were recruited since they also suffer from a muscular deficiency which often induces a scoliosis. So, 4 FA patients and 4 healthy controls have been chosen to closely match the age, weight and body mass indexes (BMI) of the patients were enrolled in our experiments. As in the previous study, electromyography (EMG) activity of paraspinal muscles were recorded on each side of the spine during three types of contraction at 2 different maximum voluntary contractions (MVC). Moreover, the volume and skinfold thickness of these muscles were determined from ultrasound images (US) in order to facilitate the interpretation of EMG signals recorded on the skin surface. For the 3 FA right scoliotic patients, EMG activity was most of the time larger on the concave side of the deviation. The opposite was found for the 4th one (P4, left scoliosis, 32°) for whom EMG activity was larger on the convex side; it should however be noted that all his signals were of small amplitude. This was associated to a muscle weakness and a large skinfold thickness (12 mm) vs 7 mm for the 3 others. As for the paraspinal muscle volume, it was present on the convex side of P1, P3 and P4 and on the concave side for P2. As for skinfold thickness over this muscle, it was larger on the concave side for P1 and P2 and the opposite for P3 and P4. At the apex of each curve, the volume and skinfold thickness differences were the largest. Although the study covers only a small number of FA patients, the presence of larger EMG signals on the concave side of a spinal deformation is similar to pre-scoliotic DMD patients for whom the deformation is in its initial stage. It thus seems that our FA patients with more EMG activity on their concave side could see progression of their spinal deformation in the coming months in spite of their already important Cobb angle.

Lower Cortisol Activity is Associated with First-Time Driving while Impaired

Driving while impaired (DWI) is a grave and persistent high-risk behavior. Previous work demonstrated that DWI recidivists had attenuated cortisol reactivity compared to non-DWI drivers. This suggests that cortisol is a neurobiological marker of high-risk driving. The present study tested the hypothesis that this initial finding would extend to first-time DWI (fDWI) offenders compared to non-DWI drivers. Male fDWI offenders (n = 139) and non-DWI drivers (n = 31) were exposed to a stress task, and their salivary cortisol activity (total output and reactivity) was measured. Participants also completed questionnaires on sensation seeking, impulsivity, substance use, and engagement in risky and criminal behaviors. As hypothesized, fDWI offenders, compared to non-DWI drivers, had lower cortisol reactivity; fDWI offenders also showed lower total output. In addition, cortisol activity was the most important predictor of group membership, after accounting for alcohol misuse patterns and consequences and other personality and problem behavior characteristics. The findings indicate that attenuated cortisol activity is an independent factor associated with DWI offending risk at an earlier stage in the DWI trajectory than previously detected.