Understanding TBI-related cognitive impairments, cognitive rehabilitation techniques and implications for evidence-based treatment of PTSD

Improvised explosive devices (IEDs) have been increasingly used in the recent conflicts in Iraq and Afghanistan. From a clinical perspective, the combined physical and psychological effects of IED blast injuries have generated particularly complex challenges for those who treat wounded service members (Sayer et al., 2009). Clinicians attempting to treat PTSD may encounter symptoms of traumatic brain injury (TBI) during treatment, although training in psychology may not adequately prepare clinicians for these issues.

Co-occurring PTSD and TBI complicate treatment because the two syndromes overlap in their clinical presentations and treatment of one can interfere with treatment of the other. Few clinicians have expertise in both conditions, with mental health professionals treating PTSD and speech-language pathologists providing cognitive rehabilitation for TBI. Unless they are part of a treatment team in a hospital setting, these clinicians rarely interact, which can compromise the effectiveness of separately developed treatment plans that fail to take co-occurring symptoms into account. To better inform clinicians whose patients experience co-occurring PTSD and TBI, this article reviews TBI symptomatology, assesses evidence-based cognitive rehabilitation techniques for TBI and identifies the impact that TBI may have on evidence-based practices (EBPs) for PTSD.

Symptomatology

A TBI occurs when a sudden trauma damages the brain. The damage can be focalized to one portion of the brain or diffused across multiple brain areas. The myriad of possible injuries include hematomas, contusions, anoxia (a lack of oxygen supply to the brain) and diffuse axonal injury (the sliding of brain tissue due to rotational forces or deceleration), which can lead to ineffective communication between neurons.

The complex and varied injuries that qualify as TBI result in symptom presentations that differ greatly from patient to patient, spanning a wide variety of physical, sensory, cognitive and psychological symptoms. Physical symptoms include dizziness, headache, vertigo and nausea; sensory symptoms include blurry vision, poor hand-eye coordination, tinnitus and changes in smell and/or taste. Physical and sensory symptoms are very difficult to treat and typically only resolve with the passing of time, if ever (National Institute of Neurological Disorders and Stroke [NINDS], 2002).

Moderate-to-severe TBIs also typically affect cognitive processes, including attention, working memory, short-term memory, long-term memory and/or executive functioning. Attention difficulties can vary from extreme deficits, such as the inability to focus on a single stimulus for more than a few seconds (focused attention), to relatively minor impairment, such as difficulties in switching rapidly between two tasks (divided attention). Memory problems, however, are the most common cognitive impairment among those with severe TBI (NINDS, 2002). Post-TBI memory impairment can include loss of specific memories (amnesia) as well as difficulty forming new memories. Executive functioning impairments can include difficulties in problem solving, decision making, organizational abilities, planning and abstract reasoning. Although some of these cognitive impairments diminish or completely resolve over time in cases of mild TBI, many with moderate to severe TBI experience lasting cognitive changes.

TBIs can also generate psychological symptoms that are primary or secondary to the changes in physical, sensory and cognitive abilities. Symptoms include irritability, anger, frustration, mood swings, confusion, depression and anxiety. Behavioral issues such as impulsivity, disinhibition, aggression and drug abuse and/or addiction can develop from the psychological symptoms, although these behavioral changes may also develop based on cognitive impairments.

Evidence-Based Cognitive Rehabilitation Techniques

Organizations such as the Academy of Neurologic Communication Disorders and Sciences and the American Congress of Rehabilitation Medicine have recently prioritized the identification of effective cognitive rehabilitation methods, leading to a rapid expansion of empirical studies. Cicerone and colleagues (2000, 2005) have completed a series of meta-analyses documenting the growth of EBPs in cognitive rehabilitation. Results from the most recent of this series (Cicerone et al., 2011) have been used to identify EBPs for cognitive rehabilitation in domains affected by TBI.

Attention

Available research shows that a combination of direct attention training and metacognitive training is most effective in remediating attention deficits (Cicerone et al., 2011). Direct attention training, which aims to improve underlying attentional abilities (Cicerone et al., 2000), is typically delivered via computerized programs in which patients complete repetitive drills over a series of sessions that stimulate discrete types of attention, depending on the severity of the impairment.

Metacognitive training improves patients' ability to think about their own thoughts and use that information to improve their thinking and behavior. It enables individuals with TBI-induced attention impairments to evaluate their progress in direct attention training and ensure that they complete the necessary tasks. Used in many areas of cognitive rehabilitation, metacognitive training is covered in more detail in the executive functioning section of this article.

Memory

Research on the cognitive rehabilitation of memory supports the combination of two types of memory strategy training: internal memory strategies and external memory compensations. They can be used in tandem, and both are intended to compensate for memory difficulties rather than restore lost memory abilities. A typical internal memory strategy would train the patient in functional routines to help develop implicit memory of how to complete day-to-day tasks (Sohlberg & Turkstra, 2011). Training first focuses on developing a list of steps necessary to complete the given goal. The therapist must help the patient complete these tasks with as few errors as possible so that the patient can correctly encode the steps. In subsequent sessions, patients practice the steps, using less and less cueing until they can complete all the steps without cueing. Patients also practice the steps at home. Once one routine has been completed and encoded, the hope is that this skill set will be generalized to other similar tasks, and the patient and therapist can move on to the next functional routine of importance to the patient.

Other internal memory techniques include visual imagery-based mnemonic memory strategies, elaboration of learned material and semantic association (Kaschel et al., 2002; O'Neil-Pirozzi et al., 2010). These strategies help patients integrate disparate pieces of information and improve depth of processing, both of which should enhance later recall (Wilson, 1995). The selection of particular strategies depends on the patient's residual abilities and comfort with the techniques.

External memory strategies can compensate for memory impairments by reinforcing the abilities that the individual retained, replacing tasks necessary for activity completion, and/or providing support to complete a task (LoPresti, Mihailidis, & Kirsch, 2004). Possible external aids range from high-tech devices such as smartphones to low-tech devices such as notebooks, alarm clocks and calculators. The evolution of the smartphone has been particularly beneficial as an external memory aid because of its ability to perform a variety of functions and act as a “second brain” for those with memory difficulties. Training begins with the same kind of systematic instruction used to train patients in functional routines (as discussed above), but with their external device. For a low-tech device such as a notebook, this presents a very simple set of steps, but for a high-tech device like a smartphone, the set of steps can be quite complicated and require extensive training. Once the patient can reliably use the external aid, the therapist introduces ways in which the patient can use the external aid to complete functional activities.

Executive Functioning

Research indicates that executive function remediation is best accomplished through metacognitive strategy training (Cicerone et al., 2011), which helps patients regulate their own behaviors and alter them if they are not meeting their goals. This is especially important for TBI patients, who are often unaware of their own deficits. They also commonly display relatively rigid patterns of thought and behavior and have difficulty responding to changing demands (Kennedy & Turkstra, 2006). Metacognitive strategy instruction (MSI; Kennedy et al., 2008) is the most widely used technique. MSI practitioners teach patients to monitor their own behavior and effectiveness in reaching goals by (a) choosing an appropriate goal, (b) thinking about the steps needed to attain the goal, (c) planning solutions for challenges that may arise, (d) monitoring progress and (e) correcting their behavior if needed to optimize progress toward the goal. MSI instruction can address difficulties with problem solving, organization, planning, task persistence and initiation of activities, all of which can impair progress in any treatment.

Other metacognitive training methods vary on multiple dimensions. Programs similar to MSI train patients to examine their own behaviors through a structured sequence of questions (Levine et al., 2000). Other programs include personal metaphor training (Ylvisaker & Feeney, 2000), in which patients identify a role model and internalize key qualities to “act” like that person, and simply recording one's perceived accuracy and efficacy in daily functioning to make patients more aware of their performance (Butler et al., 2008). Regardless of modality, metacognitive training has shown positive results in improving functionality in day-to-day tasks and goal achievement, and it has also been found effective in supplementing interventions for attention and memory (Cicerone et al., 2011).

Effects of Co-occurring TBI on Evidence-Based PTSD Treatment

Co-occurring TBI may affect PTSD treatment in a number of ways. During assessment, it may be difficult to determine which symptoms result from which syndrome. Overlapping symptoms include behavior and mood issues such as disturbed sleep, irritability, difficulty concentrating, anger, impulsivity and self-destructive or reckless behavior, as well as personality changes such as reduced interest or participation in activities important to the individual and a reduced range of affect. Although these symptoms are all easily identifiable as cause for treatment, choosing an appropriate treatment approach may prove difficult. For example, a patient presenting with impulsivity and self-destructive behavior may be dealing with severe PTSD, so metacognitive training may be ineffective. Conversely, if these are TBI-related symptoms, therapy for PTSD is unlikely to help. Diagnostic issues such as these are best clarified through an extensive clinical interview or collateral reports if available.

Attention

Impairments in attention can significantly impair a clinician's ability to treat PTSD using any treatment. If a patient cannot attend to a single stimulus for more than a number of seconds, PTSD treatment is not possible. Milder attentional impairments should allow for modified but still effective treatment. Removing artwork and plants, as well as blocking external noises from outside the therapy environment, can prevent these potential distractors from interrupting therapy sessions. The therapist may need to repeat material often and speak in short, concrete phrases for the patient to hold his or her attention. Too much information can overwhelm those with attention impairments.

Memory

If memory of the traumatic event is impaired due to TBI, any PTSD treatment may be difficult, because all EBPs for PTSD require some elaboration of the traumatic memory. Many researchers have debated whether co-occurring PTSD and TBI is even possible in such cases, arguing that PTSD cannot develop without memory of the traumatic event (King, 2008). The nature of implicit memory, however, suggests that fear responses associated with traumatic events can generate PTSD symptoms without explicit memory. Treatment using prolonged exposure (PE) techniques will be problematic, because PE requires reliving the event based on memories. Imaginal exposure cannot be implemented without memory of the event, although some of the in vivo exposure may still potentially reduce fear-related symptoms. Treatments such as cognitive processing therapy (CPT) and eye movement desensitization reprocessing (EMDR) will likely be more effective for patients with amnesia for the traumatic event, because these treatments rely on patients bringing thoughts and feelings related to the event into awareness, rather than recalling the event itself.

Patients with memory impairments may have trouble retaining content between sessions. If the patient has difficulty forming new memories, the therapist should routinely repeat key information during a session to help the patient encode it into memory. Therapists can also utilize comprehension checks at the end of session to assess the patient's understanding and retention of important material. With memory-impaired patients, CPT and PE treatment will likely progress at a slower pace than usual. EMDR therapy, however, does not necessarily require the patient to remember information from one session to the next, making it a good choice for PTSD treatment with co-occurring memory deficits.

Memory impairments can also complicate the out-of-session homework assignments required by CPT and PE treatments. Patients with impairments in forming new memories may forget to complete assignments, further delaying the progress of treatment already slowed by trouble retaining content across sessions. If a memory-impaired patient has been trained in either internal or external memory strategies, the PTSD therapist can deploy these tools to help patients complete their homework assignments. Setting up reminders on a smartphone, writing assignments in a notebook, or asking the patient to elaborate or visualize the homework assignment should improve the chances of homework completion. Alternatively, EMDR therapy, which does not require homework assignments, may be a more practical option. 

Executive Functioning

Executive functioning impairments likely pose the most difficult of TBI-related cognitive impairments for a PTSD therapist to accommodate. Patients with these symptoms typically cannot self-regulate enough to comply with some therapy protocols, and the resultant delay in symptom reduction and frustration may lead to high dropout rates.

Higher functioning patients with executive impairments may complete homework assignments but do so incorrectly because of their difficulty in monitoring the success of their behaviors. The PTSD therapist should check in with such patients regularly to gauge the success of assignments and therapy as a whole. CPT therapy may be particularly problematic because it assumes patients can engage in metacognition to examine maladaptive thoughts. Given these considerations, EMDR may be the most practical and effective treatment modality for patients with co-occurring PTSD and executive functioning impairments.

Future Directions and Conclusion

Although the number of service members returning with this constellation of symptoms continues to grow, the empirical literature regarding co-occurring PTSD and TBI is sparse. The recommendations proffered for treatment of these co-occurring syndromes were informed by the research literatures for PTSD treatment and cognitive rehabilitation for TBI-related impairments; however, they have not been empirically validated. Future research should develop and test specific PTSD and cognitive interventions for individuals with co-occurring PTSD and TBI impairments.

Despite the sparse extant literature base for co-occurring PTSD and TBI, knowledge regarding each of these syndromes has expanded rapidly in the past few decades, providing clinicians with a wealth of information to guide their decision making. Greater understanding and communication between disciplines can continue to improve care for those affected by both syndromes.

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