EEG alpha power and attentional performance during a spatial attention task in pregnant women

Pregnant women commonly report impairments in cognitive functions. Studies investigating pregnancy- associated changes in attention by using objective tests are rare. The existing literature indicates no differences in divided and focused attention between pregnant and non-pregnant women while differences in spatial attention have not been investigated so far. Larger alpha desynchronization prior to target onset is associated with better attentional performance. Our aim was to investigate whether pregnancy induce specific changes in brain activities which are related to attentional performance. 15 healthy women during their third trimester of pregnancy (M=26.6, SD=3.0 years) were compared to 15 women with a natural menstrual cycle (M=23.1 SD=4.3 years). EEG was measured while women performed a cued spatial attention paradigm. Each participant provided a saliva sample before an EEG-session for estradiol and progesterone level quantification. While response time did not differ between the two groups pregnant women showed by trend a higher accuracy than naturally cycling women. Interestingly, pregnant women showed different EEG patterns across the task with a significantly larger alpha desynchronisation during the prestimulus-period (i.e., where subjects had to shift their attention either to the left or right hemifield) and a reduced alpha desynchronization during the poststimulus interval (i.e. where subjects had to respond to the stimulus) compared to naturally cycling women. Since previous literature showed correlations between sex hormone levels and attention as well as alpha activity it can be concluded that the neuroendocrine alterations during pregnancy may in part mediate changes in brain activity which results in improved spatial attention.