ABSTRACT
Following concussion, adolescents often experience vestibular and ocular motor symptoms as well as working memory deficits that may affect their cognitive, academic and social well-being. Complex visual environments including school activities, playing sports, or socializing with friends may be overwhelming for concussed adolescents suffering from headache, dizziness, nausea and fogginess, thus imposing heightened requirements on working memory to adequately function in such environments. While understanding the relationship between working memory and vestibular/ocular motor symptoms is critically important, no previous study has examined how an increase in working memory task difficulty affects the relationship between severity of vestibular/ocular motor symptoms and brain and behavioural responses in a working memory task. To address this question, we examined 80 adolescents (53 concussed, 27 non-concussed) using functional MRI while performing a 1-back (easy) and 2-back (difficult) working memory tasks with angry, happy, neutral and sad face distractors. Concussed adolescents completed the vestibular/ocular motor screening and were scanned within 10 days of injury. We found that all participants showed lower accuracy and slower reaction time on difficult (2-back) versus easy (1-back) tasks (P-values < 0.05). Concussed adolescents were significantly slower than controls across all conditions (P < 0.05). In concussed adolescents, higher vestibular/ocular motor screening total scores were associated with significantly greater differences in reaction time between 1-back and 2-back across all distractor conditions and significantly greater differences in retrosplenial cortex activation for the 1-back versus 2-back condition with neutral face distractors (P-values < 0.05). Our findings suggest that processing of emotionally ambiguous information (e.g. neutral faces) additionally increases the task difficulty for concussed adolescents. Post-concussion vestibular/ocular motor symptoms may reduce the ability to inhibit emotionally ambiguous information during working memory tasks, potentially affecting cognitive, academic and social functioning in concussed adolescents.
ABSTRACT
Concussion among adolescents continues to be a public health concern. Yet, the differences in brain function between adolescents with a recent concussion and adolescents with no history of concussion are not well understood. Although resting state functional magnetic resonance imaging (fMRI) can be a useful tool in examining these differences, few studies have used this technique to examine concussion in adolescents. Here, we investigate the differences in the resting state functional connectivity of 52 adolescents, 38 with a concussion in the previous 10 days (mean age = 15.6; female = 36.8%), and 14 controls with no concussion history (mean age = 15.1; female = 57.1%). Independent component analysis and dual regression revealed that control adolescents had significantly greater functional connectivity between the dorsal attention network (DAN) and right inferior frontal gyrus (RIFG) compared to concussed adolescents (p-corrected < 0.001). Specifically, there was a positive DAN-RIFG connectivity in control, but not concussed, adolescents. Our findings indicate that concussion is associated with disrupted DAN-RIFG connectivity, which may reflect a general, nonspecific response to injury.
ABSTRACT
Background: Concussion symptoms in adolescents typically resolve within 4 weeks. However, 20 - 30% of adolescents experience a prolonged recovery. Abnormalities in tracts implicated in visuospatial attention and emotional regulation (i.e., inferior longitudinal fasciculus, ILF; inferior fronto-occipital fasciculus, IFOF; uncinate fasciculus; UF) have been consistently reported in concussion; yet, to date, there are no objective markers of prolonged recovery in adolescents. Here, we evaluated the utility of diffusion MRI in outcome prediction. Forty-two adolescents (12.1 - 17.9 years; female: 44.0%) underwent a diffusion Magnetic Resonance Imaging (dMRI) protocol within the first 10 days of concussion. Based on days of injury until medical clearance, adolescents were then categorized into SHORT (<28 days; N = 21) or LONG (>28 days; N = 21) recovery time. Fractional anisotropy (FA) in the ILF, IFOF, UF, and/or concussion symptoms were used as predictors of recovery time (SHORT, LONG). Forty-two age- and sex-matched healthy controls served as reference. Higher FA in the ILF (left: adjusted odds ratio; AOR = 0.36, 95% CI = 0.15 - 0.91, P = 0.030; right: AOR = 0.28, 95% CI = 0.10 - 0.83, P = 0.021), IFOF (left: AOR = 0.21, 95% CI = 0.07 - 0.66, P = 0.008; right: AOR = 0.30, 95% CI = 0.11 - 0.83, P = 0.020), and UF (left: AOR = 0.26, 95% CI = 0.09 - 0.74, P = 0.011; right: AOR = 0.28, 95% CI = 0.10 - 0.73, P = 0.010) was associated with SHORT recovery. In additional analyses, while adolescents with SHORT recovery did not differ from HC, those with LONG recovery showed lower FA in the ILF and IFOF (P < 0.014). Notably, inclusion of dMRI findings increased the sensitivity and specificity (AUC = 0.93) of a prediction model including clinical variables only (AUC = 0.75). Our findings indicate that higher FA in long associative tracts (especially ILF) might inform a more objective and accurate prognosis for recovery time in adolescents following concussion.
ABSTRACT
BACKGROUND: Prevention of suicide in individuals with early-onset bipolar disorder (BD) remains a challenge. Diffusion magnetic resonance imaging studies in BD have identified neural correlates of emotional dysregulation implicated in BD and suicide. Using diffusion magnetic resonance imaging, we sought to identify neural signatures of suicide attempts in adults with childhood-onset BD who have been clinically followed for up to 19 years as part of the COBY (Course and Outcome of Bipolar Youth) study. METHODS: Diffusion magnetic resonance imaging data were collected in 68 adults with BD: 20 in the suicide attempter (SA+) group and 48 in the non-suicide attempter (SA-) group. Multivariate analysis of covariance was used to identify the effect of group (SA+, SA-) on mean fractional anisotropy (indirect index of fiber collinearity) in key white matter tracts of emotional regulation. The effect of suicidal ideation and other clinical factors was further explored. False discovery rate was used to account for multiple comparison. Forty healthy control subjects were included. RESULTS: Analyses revealed a main effect of group on fractional anisotropy (F5,59 = 3.0, p = .017). Specifically, the SA+ group showed lower fractional anisotropy than the SA- and healthy control groups in the middle portion of the forceps minor (FMIN) (F1,63 = 8.5, p = .010) and in the anterior (F1,63 = 7.8, p = .010) and posterior (F1,63 = 8.7, p = .006) portion of the right cingulum bundle (CB). Abnormalities in the FMIN, but not CB, were also associated with suicidal ideation (F1,64 = 10.6, p = .002) and levels of emotional distress at scan. CONCLUSIONS: FMIN and CB abnormalities have been associated with emotional dysregulation in BD. Our findings suggest that the FMIN may represent a generic marker of suicidal ideation and, more broadly, emotional distress, while CB may represent a specific marker of attempted suicide.