Posted: 07.11.2014 | by AMRA

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Previous studies have shown that expectant mothers’ anxiety and stress can adversely affect their children’s brain development. If this is so, is it possible that expectant mothers’ levels of mindfulness can have a positive, protective effect on their children’s brain development?

van den Heuvel et al. [Social Cognitive and Affective Neuroscience] tested this possibility by assessing mindfulness (using a short form of the Freiburg Mindfulness Inventory) and anxiety (using a symptom checklist) in 78 expectant mothers during the second trimester of pregnancy. Nine months after their infants were born, the research team assessed the infants’ auditory processing by measuring their brain’s electrical responsiveness to sounds, or “auditory evoked event related potentials” (ERPs) using an electroencephalogram (EEG) to measure this responsiveness.

The infants were presented with series of sounds: a frequently presented tone with a base frequency of 500 vibrations per second interspersed with less frequently presented sounds such as the sound of a door slamming or a dog barking. The researchers analyzed two waveform components of the infants’ brain responses to sounds: a “P150” component (an electrically positive component of an EEG wave occurring at approximately 150 milliseconds after the presentation of a sound) reflecting selective attention to a particular stimulus together with suppression of attention to other stimuli, and an “N250” component (an electrically negative component of an EEG wave occurring at approximately 250 milliseconds after the presentation of a sound) tied to turning one’s attention to a novel stimulus.

Mothers’ mindfulness during pregnancy was associated with significantly larger infant P150 wave amplitudes and significantly smaller infant N250 wave amplitudes. Maternal anxiety during pregnancy was associated with significantly larger infant N250 wave amplitudes. These differences occurred only when the infants heard the frequently presented tone; there were no such differences in response to the more rarely presented sounds.

The authors theorize that the infants of more mindful, less anxious mothers were better able to habituate to the frequently presented tones — that is, their brains had more efficiently processed the frequently presented tones and didn’t need to keep on responding to them as if they were new. A retesting of a subset of mothers 10 months after delivery showed that post-pregnancy anxiety — unlike anxiety during pregnancy— was unrelated to their infants’ brain waveforms. Unfortunately, the researchers did not also test post-pregnancy mindfulness.

While maternal mindfulness and anxiety during pregnancy may have directly affected their infants’ fetal development, perhaps through the effects of stress hormones such as cortisol on the developing brain, the authors couldn’t rule out other causes for the observed differences in auditory processing. It could be, for example, that more mindful parents raised their children differently, or that the mindful mothers and infants shared a common genetic factor that favored the infants’ auditory processing. Only future research can tease these possibilities out.

This study raises the distinct possibility, however, that higher levels of maternal mindfulness may not only help expectant mothers reduce their anxiety, but may also benefit their children’s auditory processing, thereby facilitating their speech and language development.

Reference:

van den Heuvel, M. I., Donkers, F. C., Winkler, I., Otte, R. A., & Van den Bergh, B. R. (2014). Maternal mindfulness and anxiety during pregnancy affect infants’ neural responses to sounds. Social Cognitive and Affective Neuroscience. [PMID: 24925904]

[Link to abstract]