Improved cognitive functions after treatment with an oral appliance in obstructive sleep apnea

Åke Tegelberg,1,4,5 Bo Wilhelmsson,2 Nina Erixon-Lindroth,6 Leif H Lindström3,41Department of Stomatognathic Physiology, 2Department of Otorhinolaryngology, 3Department of Psychiatry, Central Hospital, Västerås, Sweden; 4Centre for Clinical Research, Uppsala University, Central Hospital, Västerås, Sweden; 5Faculty of Odontology, Malmö University, Malmö, Sweden; 6Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, SwedenObjective: The objective of this study was to evaluate the effect of oral appliance (OA) treatment on cognitive functions in patients with obstructive sleep apnea (OSA).Materials and methods: In a prospective study, 50 male patients with verified moderate-to-severe OSA received an OA with mandibular advancement. The cognitive functions assessed included working memory, vigilance, executive functioning, and mental pace, measured before as well as after 6 months of treatment. Somnography was used to measure physiological treatment effects. Forty-three patients completed the 6-month follow-up study.Results: All domains of cognitive functioning measured improved after 6 months of treatment with an OA (P < 0.001). The apnea/hypopnea- and oxygen desaturation-indices decreased significantly after treatment (P < 0.01). An obvious treatment response was reached in 60% of the patients, and 54% of the patients had recovered ie, had normalized breathing during sleep.Conclusion: OA with mandibular advancement is a treatment modality for the physiological symptoms of OSA, and may have a positive impact on cognitive functions, after only 6 months of treatment.Keywords: clinical trial, cognition, oral appliance, sleep apnea, treatmen

Task demands, tDCS intensity, and the COMT val158met polymorphism impact tDCS-linked working memory training gains

Abstract Working memory (WM) training paired with transcranial direct current stimulation (tDCS) can improve executive function in older adults. The unclear mechanism of tDCS likely depends on tDCS intensity, and task relevant genetic factors (e.g., for WM: COMT val158met, DAT, BDNF val66met). Higher tDCS intensity does not always lead to greater cognitive gains, and genetic polymorphisms may modulate tDCS-linked WM improvements. To evaluate these factors, 137 healthy older adults provided DNA samples and received Visual and Spatial WM training paired with tDCS (sham, 1, 1.5, 2 mA). After one session of tDCS, significant group differences in WM performance were predicted by COMT val158met status. One month after training, there was a significant interaction of tDCS intensity, COMT genotype, and WM task. Specifically, val/val homozygotes benefited most from 1.5 mA tDCS on Visual WM and from 1 mA tDCS on Spatial WM. For met/met homozygotes, 2 mA resulted in significantly poorer performance compared to 1.5 mA on Spatial WM. While this pattern was observed with relatively small sample sizes, these data indicate that variations in COMT val158met may predict the nature of WM improvement after initial and longitudinal tDCS. This contributes to our understanding of the underlying mechanism by which tDCS affects behaviour