Traumatic brain injury (TBI) is a common problem in the United States, affecting more than 1.5 million individuals each year [1
]. Injury-event related cognitive impairments, including loss of consciousness, attention and memory impairments, and/or other alterations of consciousness, are typical manifestations of biomechanically-induced alterations of brain function. They are so common that they are embedded in most clinical case definitions of TBI [3
]. In the subacute and late post-injury periods after severe TBI, impairments of attention, processing speed, episodic memory, and executive function are common [7
]. After moderate TBI, processing speed, episodic memory, and executive function also are commonly affected in both the early and late post-injury periods. Fortunately, long-term cognitive impairments of these types are not universal nor are deficits in these domains uniform within or across individuals with such injuries [8
]. When such long-term impairments occur, however, they contribute to disability [9
] and often are distressing to the person with TBI and his or her family [11
Most individuals who sustain mild TBI recover fully and do not experience long-term cognitive impairments [12
]. However, a non-trivial minority of these individuals develop persistent cognitive complaints and/or impairments [14
], the nature and etiology of which are subjects of considerable controversy [7
]. In some cases, comorbid neuropsychiatric conditions, substance use disorders, medical conditions, medications, pre-injury factors (including neurodevelopmental conditions and neurogenetics), and post-injury psychosocial issues (including litigation) may contribute to the development and persistence of cognitive complaints and/or impairments [12
]. Other patients may experience long-term cognitive problems that are misattributed to mild TBI when in fact the index injury is more than mild [16
] or preceded by prior TBI that confer vulnerability to adverse cognitive outcomes [19
]. There also may be a small subset of individuals for whom other conditions are not explanatory and whose long-term cognitive impairments reflect neurotrauma-induced disruptions of brain structure and function [20
Prior to initiating treatment specifically targeting posttraumatic cognitive impairments, a comprehensive neuropsychiatric evaluation is needed to: a) establish that an injury occurred that meets the widely-accepted definition of TBI [3
]; and b) to determine whether cognitive difficulties experienced in the post-injury period are best accounted for by TBI, another neuropsychiatric condition, iatrogenic factors (including prescribed medications), or some combination of these and other factors. Identifying and treating comorbid neuropsychiatric conditions is essential. Additionally, estimating pre-injury cognitive function, premorbid neuropsychiatric health, the role of TBI in symptom development, the effects of bodily injuries on cognitive and psychological function, the psychosocial context in which the recovery occurred, and the effects (or lack) of any treatments provided must be ascertained. It is imperative that clinicians attend to more than superficially compelling temporal relationships when evaluating persons with posttraumatic cognitive impairments. When interpreting injury history and current symptoms, care must be taken to avoid the logical fallacies of post hoc ergo propter hoc
(after TBI, therefore because of TBI) or post hoc ergo cum hoc
(with TBI, therefore because of TBI) in order to ensure that opportunities to identify and treat other causes of cognitive complaints and/or impairments are not missed.
The evidence base for nonpharmacologic and pharmacologic treatments has developed substantially over the last 20 years, and especially in the last decade [21
]. Although there are no United States Food and Drug Administration (FDA) approved treatments for cognitive impairments due to TBI, the published literature provides a useful guide to the treatment of such problems. Where evidence for the treatment of a specific type of posttraumatic cognitive impairment is lacking, modeling treatment after phenomenologically similar but etiologically distinct conditions (e.g., stroke, multiple sclerosis, neurodegenerative disorders, attention deficit hyperactivity disorder) also may be useful. The limitations of such treatments-by-analogy necessitate a measure of caution when prescribing medications or offering rehabilitative interventions to persons with posttraumatic cognitive impairments, especially with respect to treatment tolerability, safety, and cost-effectiveness. Nonetheless, clinicians are better positioned today to offer potentially useful treatments to individuals with these problems than at any time in the past.
The current treatment options described in this article are of two general types: cognitive rehabilitation and pharmacotherapy. Consistent with the citation style and clinical practice-oriented focus of this journal, evidence-based reviews, systematic reviews, meta-analyses, and other synthetic works are cited here when they serve to establish the evidence class associated with the treatment described and/or when they summarize large numbers of case reports, case series, uncontrolled studies, and expert opinions. Among those cited, a few recent articles of particular importance also are identified. Other interventions (e.g., education and counseling, technology-based interventions) are not addressed at length; interested readers are referred elsewhere [41
] for detailed reviews of these subjects.