From swing to cane: Sex differences of EEG resting-state temporal patterns during maturation and aging.

While many insights on brain development and aging have been gained by studying resting-state networks with fMRI, relating these changes to cognitive functions is limited by the temporal resolution of fMRI. In order to better grasp short-lasting and dynamically changing mental activities, an increasing number of studies utilize EEG to define resting-state networks, thereby often using the concept of EEG microstates. These are brief (around 100 ms) periods of stable scalp potential fields that are influenced by cognitive states and are sensitive to neuropsychiatric diseases. Despite the rising popularity of the EEG microstate approach, information about age changes is sparse and nothing is known about sex differences. Here we investigated age and sex related changes of the temporal dynamics of EEG microstates in 179 healthy individuals (6-87 years old, 90 females, 204-channel EEG). We show strong sex-specific changes in microstate dynamics during adolescence as well as at older age. In addition, males and females differ in the duration and occurrence of specific microstates. These results are of relevance for the comparison of studies in populations of different age and sex and for the understanding of the changes in neuropsychiatric diseases.

Efavirenz and chronic neuropsychiatric symptoms: a cross-sectional case control study.

OBJECTIVE: The aim of the study was to investigate symptoms of long-term central nervous system (CNS) toxicity in HIV-positive patients treated with efavirenz (EFV). METHODS: We carried out a single-centre, cross-sectional case-control study comparing patients treated with EFV for at least 6 months with a matched control group. Self-administered, standardized questionnaires including the Depression, Anxiety and Stress Scales (DASS), the Cognitive Failures Questionnaire (CFQ) and a questionnaire on unusual dreams, insomnia, fatigue, dizziness, depersonalization and derealization were administered. RESULTS: Data for 32 matched pairs were analysed. Significantly higher total stress scores (P=0.008) were found in the EFV group. Of the patients in this group, 19% also reported severe to extremely severe levels of stress (P=0.014), indicating increased difficulty in relaxing, and being more irritable, impatient, agitated and easily upset. Nineteen per cent of patients treated with EFV also reported severe levels of anxiety (P=0.059) as assessed with the DASS scale. This patient group also reported a higher rate of unusual dreams (P=0.049). No significant differences between groups were found for measures of cognitive impairments, fatigue, dizziness, derealization or depersonalization. CONCLUSION: EFV-treated patients reported higher levels of severe stress and anxiety as well as a higher rate of unusual dreams than patients not treated with EFV. These differences may be an expression of persisting CNS side effects in patients who remain on EFV for a prolonged period.

Mood effects of repetitive transcranial magnetic stimulation of left prefrontal cortex in healthy volunteers.

This study investigated the effect of high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) of the left prefrontal cortex (LPFC) on mood in a sham-controlled crossover design. Twenty-five healthy male subjects received HF-rTMS of the LPFC in real and sham conditions. Forty trains (frequency 20 Hz, stimulation intensity 100% of individual motor threshold, train duration 2 s, intertrain interval 28 s) were applied in each session. Mood change from baseline was measured with five visual analog scales (VAS) for sadness, anxiety, happiness, tiredness and pain/discomfort. We were unable to demonstrate significant mood changes from baseline on visual analog scales after either sham or real stimulation of LPFC. There is insufficient evidence to support the general conclusion that HF-rTMS of LPFC has mood effects in healthy volunteers. Future studies should be sham-controlled, have larger sample sizes, and strictly stimulate one single region per session in order to exclude interaction effects with the previous stimulation.