Faculty Bibliography

OBJECTIVE:To examine how positive affect influences ability to benefit from heart rate variability (HRV) biofeedback treatment for individuals with severe brain injury. METHOD/METHODS:Secondary data analysis of a nonrandomized experimental study that assessed the efficacy of biofeedback treatment for executive dysfunction in 13 individuals with chronic severe brain injury. RESULTS:Bivariate correlations between the predictors (levels of HRV and positive affect) and the outcome (change in Category Test errors) showed large effect sizes for higher levels of HRV coherence (r = -.495, p = .085) but not for positive affect (r = .069, p = .824). Although positive affect had a negligible effect on Category Test improvements by itself, positive affect played a moderating role that complemented the effect of HRV coherence. HRV coherence had a stronger effect on Category Test performance among those participants who demonstrated higher positive affect. A regression model was fit that included main effects for HRV coherence and positive affect, as well as their interaction. The interaction term was significant in a 1-tailed test (b = -3.902, SE = 1.914, p = .072). CONCLUSIONS:Participants who had the most positive emotions made the most gains in the HRV biofeedback training and performed better posttreatment on a test designed to measure problem-solving ability. Results indicate that positive affect can improve cognition, specifically mental flexibility and abstract thinking. Addressing factors that shape negative affect such as irrational beliefs and self-doubt is an important target for therapeutic intervention even in those with severe, chronic deficits. (PsycINFO Database Record

OBJECTIVE:To analyze the complex relationship between various social indicators that contribute to socioeconomic status and healthcare barriers. DESIGN/METHODS:Cluster analysis of historical patient data obtained from inpatient visits. SETTING/METHODS:Setting: Inpatient rehabilitation unit in a large, urban university hospital PARTICIPANTS: Adult patients receiving acute inpatient care, predominantly for closed head injury. INTERVENTIONS/METHODS:Not applicable MAIN OUTCOME MEASURES: We examined the membership of TBI patients in various "vulnerable group" (VG) clusters (e.g., homeless, unemployed, racial/ethnic minority) and characterized the rehabilitation outcomes of the patients (e.g., duration of stay, changes in Functional Independence Measure [FIM] scores between admission to inpatient stay and discharge). RESULTS:Analysis revealed four major clusters (i.e., Clusters A-D) separated by VG memberships, with distinct durations of stay and FIM gains during their stay. Cluster B, the largest cluster and also consisting of mostly racial/ethnic minorities, had the shortest duration of hospital stay and one of the lowest FIM improvements among the four clusters despite higher FIM scores at admission. In cluster C, also consisting of mostly ethnic minorities with multiple SES vulnerabilities, patients were characterized by low cognitive FIM scores at admission and the longest duration of stay, and they showed good improvement in FIM scores. CONCLUSIONS:Application of clustering techniques to inpatient data identified distinct clusters of patients who may experience differences in their rehabilitation outcome due to their membership in various "at-risk" groups. Results identified patients (i.e., cluster B, with minority patients and Cluster D, with elderly patients) who attain below-average gains in brain injury rehabilitation. Results also suggested that systemic (e.g., duration of stay) or clinical service improvements (e.g., staff's language skills, ability to offer substance abuse therapy, provide appropriate referrals or liaise with intensive social work services or plan subacute rehabilitation phase) could be beneficial for acute settings. Stronger recruitment, training and retention initiatives for bilingual and multiethnic professionals may also be considered to optimize gains from acute inpatient rehabilitation following traumatic brain injury.

Working memory is a complex cognitive process at the intersection of sensory processing, learning, and short-term memory and also has a general executive attention component. Impaired working memory is associated with a range of neurological and psychiatric disorders, but very little is known about how working memory relates to underlying white matter (WM) microstructure. In this study, we investigate the association between WM microstructure and performance on working memory tasks in healthy adults (right-handed, native English speakers). We combine compartment specific WM tract integrity (WMTI) metrics derived from multi-shell diffusion MRI as well as diffusion tensor/kurtosis imaging (DTI/DKI) metrics with Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) subtests tapping auditory working memory. WMTI is a novel tool that helps us describe the microstructural characteristics in both the intra- and extra-axonal environments of WM such as axonal water fraction (AWF), intra-axonal diffusivity, extra-axonal axial and radial diffusivities, allowing a more biophysical interpretation of WM changes. We demonstrate significant positive correlations between AWF and letter-number sequencing (LNS), suggesting that higher AWF with better performance on complex, more demanding auditory working memory tasks goes along with greater axonal volume and greater myelination in specific regions, causing efficient and faster information process.

We seek to elucidate the underlying pathophysiology of injury sustained after mild traumatic brain injury (MTBI) using multi-shell diffusion MRI, deriving compartment-specific WM tract integrity (WMTI) metrics. WMTI allows a more biophysical interpretation of WM changes by describing microstructural characteristics in both intra- and extra-axonal environments. Thirty-two patients with MTBI within 30 days of injury and twenty-one age- and sex-matched controls were imaged on a 3T MR scanner. Multi-shell diffusion acquisition was performed with 5 b-values (250 - 2500 s/mm²) along 6 - 60 diffusion encoding directions. Tract-based spatial statistics (TBSS) was used with family-wise error (FWE) correction for multiple comparisons. TBSS results demonstrate focally lower intra-axonal diffusivity (D_axon) in MTBI patients in the splenium of the corpus callosum (sCC) (p < 0.05, FWE-corrected). The Area Under the Curve (AUC)-value for was 0.76 with low sensitivity of 46.9%, but 100% specificity. These results indicate that D_axon may be a useful imaging biomarker highly specific for MTBI-related WM injury. The observed decrease in D_axon suggests restriction of the diffusion along the axons occurring shortly after injury.

The objective of this study was to investigate the efficacy of a group treatment protocol called NICE (Noticing you have a problem, Identifying the information you need for help, Compensatory strategies, Evaluating progress) to train help-seeking when wayfinding for individuals with acquired brain injury (ABI). Seven participants completed the NICE group treatment in an outpatient rehabilitation department at a university medical centre. A single subject multiple baseline design was employed to evaluate the efficacy of the NICE group treatment. The Social Behaviour Rating Scale and the Executive Function Route-Finding Task- Revised were repeated measures used to evaluate potential changes in help-seeking and wayfinding. Secondary outcome measures included pre- and post-treatment evaluation of social problem solving and social cognition. Results revealed that all participants improved on measures of help-seeking and wayfinding. Patterns of improvement and implications for rehabilitation are discussed. This is the first experimental study to evaluate the treatment of help-seeking behaviours and discuss its application to wayfinding in adults with ABI. Preliminary evidence supports further investigation of the NICE group treatment protocol.

BACKGROUND: Cognitive impairments are common in individuals with MS and adversely affect functioning. Early detection of cognitive impairment, therefore, would enable earlier, and possibly more effective, treatment. We sought to compare self-reports with a short neuropsychological test as possible screening tools for cognitive impairment. METHODS: One hundred patients with MS were tested with the Minimal Assessment of Cognitive Function in Multiple Sclerosis; z scores were used to derive the Cognitive Index (CI). Receiver operator characteristic curve analyses were performed, with criteria for impairment set at -1.5 and -2.0 SD below the mean. Scores from two self-reports (the Multiple Sclerosis Neuropsychological Screening Questionnaire-Patient Version and the Behavior Rating Inventory of Executive Function-Adult Version [BRIEF-A]) and a neuropsychological test (the Symbol Digit Modalities Test [SDMT]) were entered as test variables. Exploratory regression analyses were conducted with 1) CI and self-reports and 2) CI and the Problem-Solving Inventory (PSI). RESULTS: Classification accuracy was high or moderately high for SDMT when the criterion was -2.0 or -1.5 SD, respectively, but low for the self-reports. Hierarchical linear regression showed that the SDMT alone was the best predictor of cognitive impairment; adding the self-reports did not improve the model. Exploratory analyses indicated that certain self-reports (BRIEF-A, PSI) provided some explanatory power in separate models. CONCLUSIONS: The SDMT is a more accurate screening tool for cognitive impairment; however, self-reports provide additional information and may complement objective testing. Results suggest that screening for cognitive impairment may require a multidimensional approach.