A history of childhood maltreatment may lead to a preference for interpersonal distance and discomfort with fast social touch, according to a study published in the American Journal of Psychiatry.1 This phenomenon may be the result of somatosensory and insular hyperreactivity to fast touch and right hippocampal hypoactivation for slow touch.
Ayline Maier, MSc, and colleagues at the University of Bonn, Germany designed this neuroimaging study of adults (N=92; mean age, 27.8±8.50 years; 64 women) with varying levels of childhood maltreatment (low, n=33; medium, n=30; high, n=29) based on Childhood Trauma Questionnaire (CTQ) scores. At the study visit, participants were tested with an interpersonal distance paradigm in which they were asked to approach an unfamiliar experimenter and stop at self-perceived comfortable and uncomfortable distances.
In a social touch functional magnetic resonance imaging (fMRI) task, the participants rated the perceived comfort of slow, affective touch (C-tactile [CT] optimal speed: 5 cm/s) and fast, discriminative touch (non-CT-optimal speed: 20 cm/s) tactile stimulation of the shin. The main fMRI analyses, relying on voxel-based morphometry, focused on the amygdala, hippocampus, insula, and somatosensory cortex as regions of interest.
Compared to those with low CTQ scores, participants with high CTQ scores preferred a larger interpersonal distance during social interaction (P =.008). Participants with high levels of childhood maltreatment rated fast touch as less comforting compared to participants with medium (P =.003) and low (P =.002) levels of childhood maltreatment. No significant between-group differences were observed for slow touch, though lower comfort ratings with fast touch were associated with larger ideal interpersonal differences (P =.02), pointing to a common sensory sensitivity factor.
Participants with high vs low CTQ scores exhibited increased cortical reactivity to fast touch in the right primary somatosensory cortex (P =.004) and right posterior insula (P =.007). Those with high childhood maltreatment exposure also displayed decreased limbic responsiveness to slow touch in the right hippocampus (P =.006). High levels of childhood maltreatment were further linked to reduced gray matter volume in the hippocampus (left, P =.013; right, P =.048), somatosensory cortex (left, P =.001; right, P =.009), posterior insula (both P <.001), and left amygdala (P =.003).
As a limitation, Maier and colleagues were unable to identify touch response patterns based on different forms of childhood maltreatment. Nonetheless, their results provide some context for the increased susceptibility to interpersonal dysfunction and psychiatric disorders observed in adults with exposure to childhood maltreatment. The study authors concluded that “childhood maltreatment–associated structural deﬁcits in the primary somatosensory cortex and insula may reﬂect neuroplastic adaptations as a function of early physical abuse and/or touch deprivation to promote avoidance and diminish approach responses toward traumatic reminders.”
In a companion editorial,2 Martin H Teicher, MD, PhD, of the department of psychiatry, Harvard Medical School, Boston, Massachusetts, emphasized that the article “may help explain why childhood maltreatment is often associated later in life with social avoidance, social withdrawal, and isolation.”
1. Maier A, Gieling C, Heinen-Ludwig L, et al. Association of childhood maltreatment with interpersonal distance and social touch preferences in adulthood. Am J Psychiatry. 2020;177(1):37-46.
2. Teicher MH. Childhood maltreatment hampers interpersonal distance and social touch in adulthood. Am J Psychiatry. 2020 Jan 1;177(1):4-6.