Neuropsychological Characteristics of the Confusional State Following Traumatic Brain Injury.

OBJECTIVES: Individuals with moderate-severe traumatic brain injury (TBI) experience a transitory state of impaired consciousness and confusion often called posttraumatic confusional state (PTCS). This study examined the neuropsychological profile of PTCS. METHODS: Neuropsychometric profiles of 349 individuals in the TBI Model Systems National Database were examined 4 weeks post-TBI (±2 weeks). The PTCS group was subdivided into Low (n=46) and High Performing PTCS (n=45) via median split on an orientation/amnesia measure, and compared to participants who had emerged from PTCS (n=258). Neuropsychological patterns were examined using multivariate analyses of variance and mixed model analyses of covariance. RESULTS: All groups were globally impaired, but severity differed across groups (F(40,506)=3.44; p<.001; ŋp 2 =.206). Rate of forgetting (memory consolidation) was impaired in all groups, but failed to differentiate them (F(4,684)=0.46; p=.762). In contrast, executive memory control was significantly more impaired in PTCS groups than the emerged group: Intrusion errors: F(2,343)=8.78; p<.001; ŋ p 2=.049; False positive recognition errors: F(2,343)=3.70; p<.05; ŋp 2=.021. However, non-memory executive control and other executive memory processes did not differentiate those in versus emerged from PTCS. CONCLUSIONS: Executive memory control deficits in the context of globally impaired cognition characterize PTCS. This pattern differentiates individuals in and emerged from PTCS during the acute recovery period following TBI. (JINS, 2019, 25, 302-313).

Examining HPA-axis functioning as a mediator of the relationship between depression and cognition across the adult lifespan.

Altered HPA-axis functioning is a hypothesized mechanism for worsened cognition in depression. The current study examines the indirect effects of depression on processing speed, executive functioning, and memory as a function of the HPA-axis. 38 individuals with a depression diagnosis and 50 healthy controls (HCs) aged 18-86 underwent neuropsychological testing and at-home diurnal salivary cortisol collection. Depression was assessed via structured clinical interviews and rating scales. Cognitive composite scores were derived from factor analysis. Daytime cortisol exposure was estimated using area under the curve (AUC). Depression was associated with higher cortisol levels and slower processing speed . A significant suppression effect of AUC was present on the relationship between depression and processing speed. Limitations include the cross-sectional design and limited sample heterogeneity. Though poorly modulated HPA-axis is one proposed mechanism of cognitive alterations in depression, our results did not support this conclusion for processing speed. Alternative mechanisms should be considered to inform interventions to target cognitive alterations in depression.