(32) Maternal Attachment Moderates Effects of Substance Use on White-Matter Microstructure

Background &

Introduction:
Substance use decreases brain white-matter volume, impairs self-regulation in the short-term and the long-term, and alters white-matter anisotropy (1,2,5). Additionally, elevated stress and low self-regulation have been linked to substance use initiation and maintenance. While strong attachment to mothers buffers stress, poor attachment decreases self-regulation and contributes to risky behaviors, including substance use (1,4). Although considerable research has examined the relationship between substance use and white-matter microstructure, the effects of parental attachment on white-matter in youth who have engaged in various levels of substance use are not well-understood. The current study examined the associations between substance use, maternal attachment, and white-matter microstructure outcomes in prospective longitudinal data. We hypothesized that early adolescent attachment to mothers moderates the interactions between substance use involvement and white-matter anisotropy in regions of interest (ROIs) linked to self-regulation and drug exposure (2,5).

Methods:
Data were drawn from a longitudinal study on neurodevelopmental and environmental factors of substance use disorder etiology at University of Pittsburgh’s Center for Education and Drug Abuse Research. Participants were enrolled at age 10-12 and assessed biannually until age 18-22. The 31-item Youth Attachment to Parents Scale assessed youth’s trust, communication, alienation, and total attachment to parents at age 10-12. The Drug Use Chart assessed participant engagement with 42 psychoactive substances (classified into 10 major categories) across adolescence and informed development of a unidimensional substance use involvement index (3). After participants turned 18, diffusion-weighted magnetic resonance imaging (dMRI) was completed. Scans were used to compute traditional tensor-derived fractional anisotropy (FA) and assess crossing-fiber anisotropy of differently-oriented primary, secondary, and tertiary fibers within the same voxel. Selected a priori ROIs associated with self-regulation and substance use across multiple studies included the genu, body, and splenium of the corpus callosum; cingulum; uncinate fasciculus; and superior longitudinal fasciculus (SLF) (4,5). Of the participants who underwent dMRI, n = 72 had substance use and attachment data sufficient for inclusion in analyses. SPSS-PROCESS (Moderation Model 1) was employed to test the moderating effects of maternal attachment scales on associations between substance use involvement and white-matter anisotropy.

Results:
Significant interactions between substance use involvement and maternal trust were observed for fractional (p = .03) and primary fiber (p = .02) anisotropy in the right SLF; tertiary fiber anisotropy (p = .04) in the left SLF; and fractional anisotropy (p = .03) in the genu of the corpus callosum. Among individuals with high maternal trust, substance use was positively associated with fractional anisotropy in the genu of the corpus callosum and with fractional and primary fiber anisotropy in the right SLF. In those with moderate and high maternal trust, substance use was negatively associated with tertiary fiber anisotropy in the left SLF. Additionally, significant interactions between substance use involvement and maternal communication were observed for secondary fiber (p = .01) and tertiary fiber (p = .02) anisotropy in the right cingulum. Within the right cingulum, substance use was positively associated with secondary fiber anisotropy in those with high maternal communication and negatively associated with tertiary fiber anisotropy in those with low maternal communication.

Conclusion &

Discussion:
Early adolescent trust and communication with mothers moderated the relationships between substance use involvement and anisotropy in white-matter regions linked to self-regulation and drug exposure, including the genu of the corpus callosum, the SLF, and the cingulum. Crossing fiber analyses revealed complex white-matter effects: For those with high maternal trust, fractional and primary fiber anisotropy increased with increasing substance use in individuals, while tertiary fiber anisotropy decreased. Additionally, at differing levels of maternal communication, substance use had opposing effects on secondary and tertiary fiber anisotropy. Thus, trust and communication may be critical elements of familial relationships that can ameliorate substance-induced white-matter differences. Particularly, these measures of strong maternal attachment may bolster self-regulatory and reward-processing capabilities supported by the corpus callosum, SLF, and cingulum among youth exposed to substances. Moreover, the longitudinal findings may inform family-based treatment strategies that reinforce trust, implement healthy communication styles, and amplify resilience against drug-induced variations in white-matter development during adolescence.

References:
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