Tell, Don’t Ask: Communicating with Patients with Acquired Learning and Memory Impairments
Lyn S. Turkstra, PhD and Lindsey Valitchka, M.S.
Learning and memory problems in are common in patients with acquired brain injury (ABI). These impairments affect all of the patient’s daily interactions, and present a significant challenge to inpatient rehabilitation. In this article, we consider common learning profiles in patients with ABI, and how patients’ memory strengths and limitations affect not only what they learn on inpatient rehabilitation but also what we learn from them. The type of learning that is commonly impaired after ABI is declarative learning. Declarative learning, also referred to as explicit learning, is conscious learning of information related to events (episodic memory) and concepts (semantic memory). The extent to which information is learned declaratively depends on factors such as the importance of the information to the learner, how richly it is encoded, and the meaningful connections between new information and what the learner already knows. Declarative learning ability improves throughout childhood and declines slightly in the later decades of life. Declarative learning impairments are often referred to colloquially as “short-term memory problems”, because the patient tends to forget what just happened while “longer-term” (distant) memories are relatively intact. This type of learning is highly dependent on mesial temporal lobe structures, particularly the hippocampus and parahippocampal gyrus. These structures are exquisitely sensitive to loss of oxygen; thus, impairments in declarative learning are seen after any ABI etiology that involves loss of oxygen (hypoxia) or blood flow (ischemia) to the brain (Myers et al., 2008; Mecklinger et al., 1998). Declarative learning can be contrasted with implicit learning, which is unconscious learning of habits and skills and occurs primarily through repetition of reinforced behaviors (procedural learning). Emotional associations also are learned implicitly, so we often have feelings about people and events that are distinct from our declarative knowledge. The neuroanatomical basis of implicit learning has not been conclusively determined, but research points to a role for the basal ganglia, cerebellum, and other subcortical structures. Implicit learning is adult-like almost from birth, is maintained throughout life 16 BRAIN INJURY PROFESSIONAL
even in the context of profound degeneration of declarative learning (e.g., in late-stage dementia), and seems impervious to almost any type of brain damage. The typical patient with ABI has impaired declarative learning and preserved implicit learning. The difference between these two memory types is most salient in patients who are in post-traumatic amnesia (PTA). PTA is defined as the time between loss of consciousness and return of continuous memory for day-to-day events (McMillan et al., 1996), and is a syndrome of disorientation to time, place and person; confusion; diminished memory; and reduced capability for attending and responding to environmental cues (Nabors et al., 2002). In terms of learning, PTA may be best described as a stage post-injury during which declarative learning is impaired and implicit learning is intact, evidenced by intact learning of automatic motor behaviors in the context of profound impairments in learning new facts (Ewert et al., 1989). Even after PTA has resolved, it is common for patients with ABI to have persistent deficits in declarative memory, while implicit memory is preserved (Schacter, 1992). When patients have impaired declarative learning and intact implicit learning, they will learn thought and action patterns that they repeat most often, even if they have no conscious memory of learning (Cohen et al., 1985). Intact implicit memory also means the patient can learn emotional associations. For example, the patient might “have a good feeling” about a staff person or place, without any recollection of the event attached to that feeling. During a typical rehabilitation day, a patient learns new skills and information using both implicit and declarative memory systems, to the extent that he or she is able. It is possible, however, that rehabilitation staff might not formally consider the two types of learning when planning intervention for an individual patient. Further, therapists might not be aware of learning that occurs outside of therapy, much of which may be implicit. Medicare regulations dictate that patients must be in direct therapy for at least 15 hours each week. Assuming that the patient is awake for 12 hours each day, that leaves 69 hours each week in which the patient may