Mindfulness and anxiety are two inversely linked traits that have been independently attributed to a range of cognitive functions. The primary aim of the thesis was to look into the combined effects of mindfulness and anxiety on a series of executive functions. A cross-sectional study with two experimental groups, high mindfulness-low anxiety (HMLA) and low mindfulness-high anxiety (LMHA), was conducted based on findings from a behavioral study investigating the effects of a brief mindfulness induction on motor inhibitory control, measured using a stop signal task (SST). This cross-sectional study investigated a series of executive functions using the attentional network test (ANT) to measure the efficiency of attentional networks, a color Stroop task (CST) to measure the conflict control ability and a change detection task (CDT) to measure the visuospatial working memory capacity. Additionally, neural indices that may reveal the fundamental differences in cognitive functions and spontaneous resting state between the two experimental groups were explored. Advanced EEG analytical approaches, Hilbert-Huang Transform analysis (HHT) and Holo-Hilbert Spectral Analysis (HHSA) were employed to analyze data relating to both cognitive functions and resting state activity.
Initial behavioral results showed no significant change in motor control, indexed by altered stop signal reaction time (SSRTs), following interventions including a mindfulness condition, although there was a marginal trend of reduction of SSRT, indicative of better inhibitory control, in the mindfulness condition. In the cross-sectional study, the HMLA group was more accurate than the LMHA group on the Stroop and change detection tasks. Additionally, the HMLA group was more sensitive in detecting changes and had a higher WMC than the LMHA group. However, on the ANT, there were no differences on any of the three attentional networks; with alerting, orienting and conflict scores not significantly differing between the two groups. The higher accuracy rate on the CST in the HMLA group was associated with lower delta EEG activity in posterior temporal and occipital areas, indicating a more attentive state in this group. The higher accuracy rate and WMC in the HMLA group was seen in conjunction with enhanced alpha activity in PFC, fronto-central and centro-parietal regions during the retrieval phase, indicating active allocation of brain resources in this group. In the resting state, the presence of higher oscillation power across the frequency bands in the LMHA group than the HMLA group was a novel finding. This might have been due to higher physiological arousal either as a consequence of uncertainty relating to the resting state or more preparedness for upcoming situations. To investigate individual contributions of mindfulness and anxiety to such differences, future studies could usefully look into how a mindfulness intervention, such as meditation, may alter the dynamics of resting state and cognitive functions as well as their association with levels of anxiety.
