Alleviating attentional disturbances following traumatic brain injury

2017-02-21T23:02:40Z (GMT) by Dymowski, Alicia Rhian
Attentional impairments following traumatic brain injury (TBI) are common, and often significantly debilitating. Debate continues as to whether deficits in strategic control of attention are proportionate to, or remain after controlling for, reduced speed of information processing. Despite the debate, attention and speed deficits interfere with return to life roles, necessitating early remediation. Pharmacological treatment with immediate-release methylphenidate (MP) has been shown to improve processing speed, attentiveness and caregiver ratings of attention after TBI. To date, there has been no investigation of the safety or efficacy of extended-release MP in this population, which has the advantage of once daily administration. Non-pharmacological rehabilitation techniques include restorative approaches (e.g. computer training) and compensatory approaches (e.g. strategy training). As yet, there is limited documentation of the experience of individuals with TBI undertaking either of these approaches. The study aims were to 1) investigate whether individuals with TBI demonstrated greater deficits in performance on traditional and novel attentional tasks with increased working memory or executive load relative to healthy controls, after controlling for slowed information processing. In an attempt to rehabilitate such deficits, subsequent aims were to 2) determine proof of concept, in a pilot study, that once daily dosing with extended-release MP would be tolerated and associated with improvements on processing speed and complex attentional measures, ratings of everyday attentional behaviour and functional outcomes after TBI; and 3) in a series of single-case studies, investigate the effects of individualised strategy training beyond the effects of computerised training with Attention Process Training 3 (APT-3) on tests of attention, generalisation to an ecological attention task, and ratings of everyday attentional behaviour, and to examine subjective experience of these approaches. In the first study 25 individuals with TBI and 25 matched controls were assessed on a range of attentional and executive measures. Individuals with TBI demonstrated slowed speed of processing on the Symbol Digit Modalities Test (SDMT), visual n-back task, computerised selective attention Test (SAT), Ruff 2&7 Selective Attention Test (2&7), Hayling Test and Trail Making Test A. There was no difference between groups in working memory performance on Digit Span. Individuals with TBI demonstrated disproportionate increase in reaction time with complexity, which was accounted for by speed on the SAT, but remained after controlling for speed on the Hayling Inhibition Test. The TBI group made more errors on the Hayling Test, misses on the n-back and were unable to benefit from the 2&7 automatic condition. Thus, deficits in processing speed were pervasive and there was evidence of impaired strategic control on a response inhibition task. The second study was a pilot randomised, placebo-controlled, double-blind, parallel trial. Ten individuals with TBI and attention deficits received daily extended-release MP or placebo for seven weeks. Assessments were conducted at baseline, week 8 (on-drug), week 9 (off-drug) and 7 months follow-up. Vital signs and side effects were monitored weekly. MP did not enhance performance on attention or processing speed measures, or functional outcomes. There were greater improvement ratios for the MP relative to placebo group from baseline to week 8 (on-drug) for ratings of everyday attentional behaviour. MP was associated with increased blood pressure and anxiety. Extended-release MP may be used to improve everyday attention after TBI, but monitoring is important given potential for changes in vital signs and side effects. A large number of individuals were ineligible or declined to participate in this drug study. Hence, the efficacy of non-pharmacological interventions should also be investigated. The single-case series study, with ABCA (baseline, APT-3, strategy training, follow-up) design, included three individuals with attention deficits following severe TBI. Improvements were evident on SDMT and automatic condition of the cancellation tasks after APT-3 and follow-up, but most improvement was observed after strategy training. There was limited generalisation on the Test of Everyday Attention and self-ratings of everyday attentional behaviour. Significant other ratings of everyday attentional behaviour were mixed after APT-3 but demonstrated improvement after strategy training. Variability in attentional deficits and everyday attentional requirements necessitated individualised goals and interventions between participants. Research should continue to investigate pharmacological and non-pharmacological approaches to remediate attention after TBI to ensure rehabilitation can be tailored to individuals and their everyday attentional demands.