Predictors and Functional Outcomes Associated With Longitudinal Trajectories of Anxiety and Depression from 2 to ≥36 Months After Moderate to Severe Traumatic Brain Injury.

This study investigated longitudinal trajectories of anxiety and depressive symptoms following moderate-severe traumatic brain injury (TBI), predictors of the trajectories, and associations with 1-year return to productivity. One hundred forty-eight patients with moderate-severe TBI were assessed at 2, 5, 12, and ≥36 months post-injury on the Beck Anxiety Inventory and the Beck Depression Inventory. Clinical interviews obtained information about demographics, injury characteristics, and 1-year return to productivity. Latent growth mixture modeling identified trajectories of anxiety and depression across time. The three-step method identified predictors of trajectories, and χ2 analyses determined associations between trajectories and 1-year return to productivity. Analyses revealed that four-class models of anxiety and depression best fit the data. Most individuals had stable minimal (67%) or low (18%) levels of anxiety over time. Two other subsets of individuals were classified by anxiety that worsened rapidly (7%) or improved in the 1st year but worsened by 3 years post-injury (9%). Similarly for the depression trajectories, most individuals had stable minimal (70%) or low (10%) levels of depression over time. Others had depression that worsened rapidly (12%) or was delayed, with onset 1-year post-injury (8%). Predictors of worsening anxiety and depression included younger age, less education, and male gender. Those with worsening anxiety or depression were less likely to return to productivity by 1-year post-injury. There is a significant burden of anxiety (15%) and depression (20%) in the 3 years after moderate-severe TBI. Future research targeting at-risk patients may help to improve quality of life and functional recovery.

Impact of Mesial Temporal Lobe Resection on Brain Structure in Medically Refractory Epilepsy.

OBJECTIVE: Surgical resection can decrease seizure frequency in medically intractable temporal lobe epilepsy. However, the functional and structural consequences of this intervention on brain circuitry are poorly understood. We investigated structural changes that occur in brain circuits after mesial temporal lobe resection for refractory epilepsy. Specifically, we used neuroimaging techniques to evaluate changes in 1) contralesional hippocampal and bilateral mammillary body volume and 2) brain-wide cortical thickness. METHODS: Serial T1-weighted brain magnetic resonance images were acquired before and after surgery (1.6 ± 0.5 year interval) in 21 patients with temporal lobe epilepsy (9 women, 12 men; mean age, 39.4 ± 11.5 years) who had undergone unilateral temporal lobe resection (14 anterior temporal lobectomy; 7 selective amygdalohippocampectomy). Blinded manual segmentation of the unresected hippocampal formation and bilateral mammillary bodies was performed using the Pruessner and Copenhaver protocols, respectively. Brain-wide cortical thickness estimates were computed using the CIVET pipeline. RESULTS: Surgical resection was associated with a 5% reduction in contralesional hippocampal volume (P < 0.01) and a 9.5% reduction in mammillary body volume (P = 0.03). In addition, significant changes in cortical thickness were observed in contralesional anterior and middle cingulate gyrus and insula (Pfalse discovery rate < 0.01) as well as in other temporal, frontal, and occipital regions (Pfalse discovery rate < 0.05). Postoperative verbal memory function was significantly associated with cortical thickness change in contralesional inferior temporal gyrus (R2 = 0.39; P = 0.03). CONCLUSIONS: These results indicate that mesial temporal lobe resection is associated with both volume loss in spared Papez circuitry and changes in cortical thickness across the brain.

Longitudinal Recovery of Executive Control Functions After Moderate-Severe Traumatic Brain Injury: Examining Trajectories of Variability and Ex-Gaussian Parameters.

BACKGROUND: Executive control deficits are deleterious and enduring consequences of moderate-severe traumatic brain injury (TBI) that disrupt everyday functioning. Clinically, such impairments can manifest as behavioural inconsistency, measurable experimentally by the degree of variability across trials of a reaction time (RT) task (also known as intraindividual variability [IIV]). Growing research on cognition after TBI points to cognitive deterioration in the chronic stages postinjury. OBJECTIVE: To examine the longitudinal recovery of RT characteristics (IIV and more detailed ex-Gaussian components, as well as the number of impulsively quick responses) following moderate-severe TBI. METHODS: Seventy moderate-severe TBI patients were assessed at 2, 5, 12, and 24+ months postinjury on a go/no-go RT task. RT indices (ex-Gaussian parameters mu and sigma [mean and variability of the normal distribution component], and tau [extremely slow responses]; mean, intraindividual coefficient of variation [ICV], and intraindividual standard deviation [ISD]) were analyzed with repeated-measures multivariate analysis of variance. RESULTS: ICV, ISD, and ex-Gaussian tau significantly decreased (ie, improved) over time in the first year of injury, but worsened from 1 to 2+ years, as did the frequency of extremely fast responses. These quadratic patterns were accentuated by age and shown primarily in tau (extremely slow) and extremely fast (impulsive) responses. CONCLUSIONS: The pattern of early recovery followed by decline in executive control function is consistent with growing evidence that moderate-severe TBI is a progressive and degenerative disorder. Given the responsiveness to treatment of executive control deficits, elucidating the trajectory and underpinnings of inconsistent behavioral responding may reveal novel prognostic and clinical management opportunities.

Feasibility of online self-administered cognitive training in moderate-severe brain injury.

PURPOSE: Cognitive environmental enrichment (C-EE) offers promise for offsetting neural decline that is observed in chronic moderate-severe traumatic brain injury (TBI). Brain games are a delivery modality for C-EE that can be self-administered over the Internet without therapist oversight. To date, only one study has examined the feasibility of self-administered brain games in TBI, and the study focused predominantly on mild TBI. Therefore, the primary purpose of the current study was to examine the feasibility of self-administered brain games in moderate-severe TBI. A secondary and related purpose was to examine the feasibility of remote monitoring of any C-EE-induced adverse symptoms with a self-administered evaluation tool. METHOD: Ten patients with moderate-severe TBI were asked to complete 12 weeks (60 min/day, five days/week) of online brain games with bi-weekly self-evaluation, intended to measure any adverse consequences of cognitive training (e.g., fatigue, eye strain). RESULTS: There was modest weekly adherence (42.6% ± 4.4%, averaged across patients and weeks) and 70% patient retention; of the seven retained patients, six completed the self-evaluation questionnaire at least once/week for each week of the study. CONCLUSIONS: Even patients with moderate-severe TBI can complete a demanding, online C-EE intervention and a self-administered symptom evaluation tool with limited therapist oversight, though at daily rate closer to 30 than 60 min per day. Further self-administered C-EE research is underway in our lab, with more extensive environmental support. Implications for Rehabilitation Online brain games (which may serve as a rehabilitation paradigm that can help offset the neurodegeneration observed in chronic TBI) can be feasibly self-administered by moderate-to-severe TBI patients. Brain games are a promising therapy modality, as they can be accessed by all moderate-to-severe TBI patients irrespective of geographic location, clinic and/or therapist availability, or impairments that limit mobility and access to rehabilitation services. Future efficacy trials that examine the effect of brain games for offsetting neurodegeneration in moderate-to-severe TBI patients are warranted.

Negative neuroplasticity in chronic traumatic brain injury and implications for neurorehabilitation.

Based on growing findings of brain volume loss and deleterious white matter alterations during the chronic stages of injury, researchers posit that moderate-severe traumatic brain injury (TBI) may act to "age" the brain by reducing reserve capacity and inducing neurodegeneration. Evidence that these changes correlate with poorer cognitive and functional outcomes corroborates this progressive characterization of chronic TBI. Borrowing from a framework developed to explain cognitive aging (Mahncke et al., Progress in Brain Research, 157, 81-109, 2006a; Mahncke et al., Proceedings of the National Academy of Sciences of the United States of America, 103(33), 12523-12528, 2006b), we suggest here that environmental factors (specifically environmental impoverishment and cognitive disuse) contribute to a downward spiral of negative neuroplastic change that may modulate the brain changes described above. In this context, we review new literature supporting the original aging framework, and its extrapolation to chronic TBI. We conclude that negative neuroplasticity may be one of the mechanisms underlying cognitive and neural decline in chronic TBI, but that there are a number of points of intervention that would permit mitigation of this decline and better long-term clinical outcomes.

Age-related differences in attentional bias for emotional faces.

Past research suggests an aging-related positivity effect in orienting to faces. However, these studies have eschewed direct comparison of orienting when positive and negative faces are presented simultaneously, thereby potentially underestimating the degree to which emotional valence influences such effects. In the current study younger and older adults viewed face pairs for 1000 ms, and upon face-pair offset indicated the location of a dot that appeared in the former location of one of the faces, to assess attentional orienting. When shown negative-neutral pairs, both age groups were biased to attend to negative faces, but when shown positive-negative pairs only younger adults showed a bias toward negative; older adults showed a lack of orienting toward either emotional face. Results suggest younger adults have a negativity bias in attention orienting regardless of the valence of nearby stimuli, whereas older adults show an absence of this bias when positive information is present.

A positivity effect in older adults' memorability judgments of pictures.

UNLABELLED: BACKGROUND/STUDY CONTEXT: A growing literature suggests that older adults are biased to preferentially cognitively process positively valenced information. The authors investigated whether this bias extended to preferential selection of information to remember, and also examined whether the arousal invoked by stimuli biased item selection and memory. METHODS: Thirty older (63-88 years of age) and 30 younger (18-25 years of age) adults viewed emotional (positive, negative) and neutral pictures that varied in arousal (low, high), and were asked to select a subset they deemed memorable (memorability judgments), before recalling pictures. Repeated-measures analyses of variance were conducted to examine aging-related differences in selection and recall of positive, negative, and neutral pictures, and of low- and high-arousal pictures. RESULTS: Older adults selected more positive pictures as memorable, whereas in younger adults selection did not differ by valence. In both age groups, recall of positive pictures was highest. Older adults selected more low- than high-arousal pictures as memorable, although recall was greater for high- than low-arousal pictures in both age groups. CONCLUSION: Findings are consistent with the view that the aging-related positivity bias is under cognitive control, and suggest an awareness of this in older adults. Future investigations should seek to disentangle the influence of positive valence from other factors (e.g., perceptual, semantic, arousal level) on older adults' memorability judgments.

A positivity effect in autobiographical memory, but not phonemic fluency, in older adults.

To investigate whether processing fluency or cognitive control processes underlie aging-related positivity effects in memory, we compared retrieval of words on a fluency task, and of events on an autobiographical task, in younger and older adults. No positivity effect in word output was found on the fluency task, though older adults output more neutral words. For our autobiographical task, participants wrote descriptions of personal events related to cue words (3 each of positive, negative, neutral). They then classified their memories by valence, and subsequently rated how they 'felt now' about each. Older adults output more autobiographical memories classified as positive, and rated their memories more positively than did younger adults. We suggest the aging-related positivity effect emerges in service of emotion regulation, and is primarily observed when the cognitive task allows for personal evaluation and/or engages a reflective style of processing, as on an autobiographical but not a fluency task.

Personal relevance modulates the positivity bias in recall of emotional pictures in older adults.

Some studies have suggested that older adults remember more positive than negative valence information, relative to younger adults, whereas other studies have reported no such difference. We tested whether differences in encoding instructions and in personal relevance could account for these inconsistencies. Younger and older adults were instructed either to passively view positive, negative, and neutral pictures or to actively categorize them by valence. On a subsequent incidental recall test, older adults recalled equal numbers of positive and negative pictures, whereas younger adults recalled negative pictures best. There was no effect of encoding instructions. Crucially, when the pictures were grouped into high and low personal relevance, a positivity bias emerged in older adults only for low-relevance pictures, suggesting that the personal relevance of pictures may be the factor underlying cross-study differences.