Deficits in attention are frequently reported following severe traumatic brain injury (TBI). However, methodological differences make it difficult to reconcile inconsistencies in the research findings in order to undertake an evidence-based assessment of attention. The current study therefore undertook a meta-analytic review of research examining attention following severe TBI. A search of the PsycINFO and PubMed databases spanning the years 1980 to 2005 was undertaken with 24 search terms. Detailed inclusion and exclusion criteria were used to screen all articles, leaving 41 studies that were included in the current meta-analysis. Weighted Cohen's d effect sizes, percentage overlap statistics, and confidence intervals were calculated for the different tests of attention. Fail-safe Ns were additionally calculated to address the bias introduced by the tendency to publish significant results. Large and significant deficits were found in specific measures of information-processing speed, attention span, focused/selective attention, sustained attention, and supervisory attentional control following severe TBI. Finally, age, education, and postinjury interval were not significantly related to these deficits in attention.

Pharmacological treatments that are administered to adults in the postacute stage after a traumatic brain injury (TBI) (≥4 weeks after injury) have the potential to reduce persistent cognitive and behavioral problems. While a variety of treatments have been examined, the findings have yet to be consolidated, hampering advances in the treatment of TBI. A meta-analysis of research that has investigated the cognitive and behavioral effects of pharmacological treatments administered in the later stage after TBI was therefore conducted. The PubMed and PsycINFO databases were searched, and Cohen d effect sizes, percent overlap, and failsafe N statistics were calculated for each treatment. Both randomized controlled trials and open-label studies (prospective and retrospective) were included. Nineteen treatments were investigated by 30 independent studies, comprising 395 participants with TBI in the treatment groups and 137 control subjects. When treated in the postacute period, 1 dopaminergic agent (methylphenidate) improved behavior (anger/aggression, psychosocial function) and 1 cholinergic agent (donepezil) improved cognition (memory, attention). In addition, when the injury-to-treatment interval was broadened to include studies that administered treatment just before the postacute period, 2 dopaminergic agents (methylphenidate, amantadine) showed clinically useful treatment benefits for behavior, whereas 1 serotonergic agent (sertraline) markedly impaired cognition and psychomotor speed.

Brain/biological (BR) and cognitive/neural reserve (CR) have increasingly been used to explain some of the variability that occurs as a consequence of normal ageing and neurological injuries or disease. However, research evaluating the impact of reserve on outcomes after adult traumatic brain injury (TBI) has yet to be quantitatively reviewed. This meta-analysis consolidated data from 90 studies (published prior to 2015) that either examined the relationship between measures of BR (genetics, age, sex) or CR (education, premorbid IQ) and outcomes after TBI or compared the outcomes of groups with high and low reserve. The evidence for genetic sources of reserve was limited and often contrary to prediction. APOE ∈4 status has been studied most, but did not have a consistent or sizeable impact on outcomes. The majority of studies found that younger age was associated with better outcomes, however most failed to adjust for normal age-related changes in cognitive performance that are independent of a TBI. This finding was reversed (older adults had better outcomes) in the small number of studies that provided age-adjusted scores; although it remains unclear whether differences in the cause and severity of injuries that are sustained by younger and older adults contributed to this finding. Despite being more likely to sustain a TBI, males have comparable outcomes to females. Overall, as is the case in the general population, higher levels of education and pre-morbid IQ are both associated with better outcomes.

No abstract

Early pharmacological treatment has the potential to reduce some of the disabling cognitive and behavioral problems that result from traumatic brain injury (TBI). Although a large number of treatments have been developed, clinical research has yielded inconsistent findings with respect to the effectiveness of these pharmacological treatments on cognitive and behavioral outcomes. Furthermore, their relative efficacy has not been evaluated, thereby hindering advances in the treatment of TBI. A meta-analysis of research that examined the impact of pharmacological treatments on cognitive and behavioral outcomes in the early stages after TBI between January 1980 and May 2008 was therefore undertaken. The PubMed and PsycINFO databases were searched using 35 terms. All articles were screened using detailed inclusion criteria. Weighted Cohen's d effect sizes, percent overlap statistics, and fail-safe N statistics were calculated for each pharmacological agent. Studies that used different experimental designs were examined separately. Eleven pharmacological treatments were investigated by 22 clinical studies, comprising 6472 TBI patients in the treatment groups and 6460 TBI controls. One dopamine agonist (amantadine) and 1 bradykinin antagonist (CP-0127 [Bradycor]) produced marked treatment benefits (d > or = 0.8) for a single measure of arousal (Glasgow Coma Scale). Notably, drug dosage and the measure chosen to assess outcome influenced the probability of finding a treatment benefit.