BackHome
Refresh: OffView Personal Schedule
Individual Submission Summary
Share...

Direct link:

Poster #16 - Sensitive periods of stress predict nucleus accumbens volume in adolescents

Thu, March 21, 4:00 to 5:15pm, Baltimore Convention Center, Floor: Level 1, Exhibit Hall B

Integrative Statement

Background:
Exposure to childhood adversity or early life stress (ELS) is relatively common in the general population and a significant risk factor for maladaptive mental and physical health outcomes in adolescents (McLaughlin et al., 2012). While ELS has been associated with structural alterations in the development of numerous brain structures--including the hippocampus, amygdala, and prefrontal cortex—relatively few studies have examined the effects of ELS on structural changes in the nucleus accumbens (NAcc; Teicher et al., 2016). Importantly, the NAcc undergoes significant morphological changes (specifically decreases in gray matter volume) during adolescence (Mills et al., 2014), highlighting the importance of understanding whether individuals who have been exposed to ELS exhibit altered NAcc structure development. An important unanswered question with significant implications for prevention (i.e., identifying children who are at the greatest risk for disorders characterized by alterations in NAcc, such as depression) is whether the NAcc is vulnerable to life stress throughout childhood or, alternatively, whether there is a period of increased vulnerability to stress (i.e., a sensitive period during which life stress exerts greater relative influence). To address this question, we examined whether there are sensitive periods of ELS that are associated with NAcc volumes in adolescence.

Methods:
In a community sample of 122 adolescents ages 11–14 years (69 male; mean ± SD age: 12.05 ± 0.80), we comprehensively assessed exposure to over 30 stressors through structured interviews of the child. An independent panel of coders rated severity of child-reported events from a scale of 1–5 (1=no impact); in addition, we obtained information about ages during which these stressful events occurred (King et al., 2017; 2018). All participants completed a T1-weighted MRI scan with which we estimated left and right NAcc gray matter volume (GMV) using FreeSurfer. As in previous work, we used random forest regressions with conditional trees using ‘cforest’ in R to determine if left or right NAcc volume (separately) were associated with sensitive periods of stress (Teicher et al., 2018).

Results:
Among all predictors, we found evidence that severity of stress occurring at age 4 years was the most important predictor of NAcc GMV in adolescents (left: Z=3.091, p=0.018; right: Z=2.028, p=0.038; see Figure 1). Post-hoc linear regression analyses isolating that predictor indicated that maximum severity of stressors occurring at age 4 predicted larger NAcc GMV.

Conclusions:
This research provides preliminary evidence that age 4 years may be a sensitive period for NAcc GMV. Previous studies have shown adolescent-typical decreases in NAcc GMV across development (Mills et al., 2014), combined with increases in NAcc activation to rewarding stimuli (Spear, 2011). Thus, in interpreting our associations of greater severity of stressors occurring at age 4 with greater NAcc GMV during early adolescence, we posit that ELS alters development of NAcc GMV such that larger volume may reflect a compensatory mechanism following blunted NAcc responses to positive environmental stimuli (Hanson et al., 2015; 2016; 2018). Future studies examining sensitive periods of NAcc function should test this formulation more explicitly.

Authors