A Cross-sectional Cohort Study to Assess Long-term Neurocognitive and Psychiatric Symptoms of Mefloquine Use in Veterans.

INTRODUCTION: To evaluate the associations between neurocognitive and psychiatric health outcomes with mefloquine or any antimalarial exposure. MATERIALS AND METHODS: Medical records were systematically reviewed to identify veterans that indicated antimalarial medication use. Linear regression was performed to examine associations between mefloquine/antimalarial exposure and health outcomes. The mefloquine-exposed group was further compared with normative populations for the same health outcomes. RESULTS: In the adjusted models, no significant differences were noted between the two exposure groups and the unexposed group for any of the health measures (P-value > 0.05). When compared to normative population samples, the mefloquine-exposed group had poorer health and greater neurobehavioral symptom severity or cognitive complaints. CONCLUSION: This study suggests that mefloquine use by veterans referred for intensive evaluation of their military deployment exposures and health was not associated with increased, long-term, neurocognitive/psychiatric symptoms compared to unexposed veterans.

Aftereffects of frontoparietal theta tACS on verbal working memory: Behavioral and neurophysiological analysis.

Verbal working memory is supported by a left-lateralized frontoparietal theta oscillatory (4-8 Hz) network. We tested whether stimulating the left frontoparietal network at theta frequency during verbal working memory can produce observable after-stimulation effects in behavior and neurophysiology. Weak theta-band alternating electric currents were delivered via two 4 × 1 HD electrode arrays centered at F3 and P3. Three stimulation configurations, including in-phase, anti-phase, or sham, were tested on three different days in a cross-over (within-subject) design. On each test day, the subject underwent three experimental sessions: pre-, during- and post-stimulation sessions. In all sessions, the subject performed a Sternberg verbal working memory task with three levels of memory load (load 2, 4 and 6), imposing three levels of cognitive demand. Analyzing behavioral and EEG data from the post-stimulation session, we report two main observations. First, in-phase stimulation improved task performance in subjects with higher working memory capacity (WMC) under higher memory load (load 6). Second, in-phase stimulation enhanced frontoparietal theta synchrony during working memory retention in subjects with higher WMC under higher memory loads (load 4 and load 6), and the enhanced frontoparietal theta synchronization is mainly driven by enhanced frontal→parietal theta Granger causality. These observations suggest that (1) in-phase theta transcranial alternating current stimulation (tACS) during verbal working memory can result in observable behavioral and neurophysiological consequences post stimulation, (2) the short-term plasticity effects are state- and individual-dependent, and (3) enhanced executive control underlies improved behavioral performance.