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Article Excerpt
The development of neuropsychology and the study of human memory have demonstrated that individuals with a number of different disabilities are at risk for memory deficits. Substance abuse, HIV infection/AIDS, mental retardation, schizophrenia, and diabetes mellitus are examples of clinical diagnoses that carry a risk for concomitant memory disturbances (Lezak, 1995).
Ruff and Schraa (2001) suggested that detecting the specific cognitive difficulties of clients not only assists in planning rehabilitation but also facilitates client awareness of such problems and engagement in participating more fully in the rehabilitation program. Stringer and Naldone (2000) described the role of neuropsychological assessment in rehabilitation settings and in planning of vocational/educational goals. They pointed out the importance of identifying cognitive and behavioral deficits to better understand their possible effects on the individual's ability to carry out activities of daily living. Also, by identifying such deficits, cognitive rehabilitation efforts can be designed to integrate with other rehabilitation programming. Memory deficits, for example, may compromise the learning of a work routine and adaptation to new contexts. The identification of memory difficulties allows the rehabilitation counselor to include mnemonic strategies and compensation procedures in the rehabilitation plan that may facilitate successful outcomes.
Traditionally, rehabilitation counselors have tended to refer clients for neuropsychological assessment only when their primary diagnoses have a clear and direct relation to neurological deficits. According to data from the Longitudinal Study of Vocational Rehabilitation Search Program (n.d.), counselors referred only 338 clients for neuropsychological assessment from a sample of 8,500 DVR clients, even though the sample included 170 clients with traumatic brain injury as the primary disability. It appears that potential memory deficits may often not be assessed, even when the risk of occurrence is substantial, which may lead to unrealistic goals and failure to achieve successful rehabilitation outcomes.
The present paper will focus on memory assessment in vocational rehabilitation for clients who may not have diagnosed neurological disorders but may be at risk for significant memory deficits. First, a summary of the major theoretical aspects of memory as a construct will be presented, along with studies of memory disorders in individuals with diagnoses of schizophrenia, substance abuse, and mental retardation, providing examples of groups of clients that may benefit from memory assessment. Later, a model of assessment will be suggested and major memory assessment tools will be presented as instruments to be used in the assessment of memory in rehabilitation settings.
Theoretical Models of Memory Function
Lezak (1995) defined memory as "the complex systems by means of which an organism registers, stores, retains, and retrieves some previous exposure to an event or experience" (p. 429). Memory is intertwined with learning and, consequently, is important to the successful implementation of many rehabilitation services and interventions.
There is agreement in the literature that memory cannot be regarded as a unitary faculty (Baddeley, 2002). Several classification systems have been proposed, for example, according to duration (short-term and long-term memory) and content (declarative and non-declarative memory). A thorough review of theories of memory is beyond the scope of the present paper, and only a few of the most relevant aspects of the psychology of memory to vocational rehabilitation will be considered here.
Memory is frequently viewed in terms of three stages: encoding (the processes by which information is registered), storage (the maintenance of information over time), and retrieval (the accessing of information). These processes are engaged by a variety of brain structures which are governed and regulated by mechanisms of facilitation and inhibition. Memory difficulties can be related to an array of circumstances linked to both anatomical and chemical changes in the brain and external/contextual features of events/stimuli.
From a mnemonic duration perspective, memory traces are distinguished based on the duration and the capacity of the storage (Sohlberg, & Mateer, 2001). Two major memory systems can be listed: working memory and long-term memory. Working memory has been defined as a limited capacity memory that is used for manipulating information while reasoning and learning (Baddeley, 1997). It comprehends the central executive (an attentional controller), a phonological loop (a store that holds memory traces for a couple of seconds using subvocal speech), and the visuospatial sketchpad (the temporary storage and manipulation of visual and spatial information) (Baddeley, 1997). The working memory system influences the following abilities: attending to current events, maintaining selected information, and integrating the information with experiences stored in long-term memory (Oram, Geffen, Geffen, Kavanagh, & McGrath, 2005).
Long-term memory would hold the information permanently and would also have an unlimited capacity of storage. It can be subdivided considering on the basis of content: explicit (declarative) and implicit (non-declarative) memory. Declarative memory concerns the capacity to recollect specific experiences from the past, called episodic memory, as well as the generic knowledge of the world, called semantic memory (Baddeley, 2002). Implicit memory refers to retention of the processes that are involved in performing tasks such as automatic skills and habits (Cermak, 1990). Furthermore, memory can also be classified according to a temporal perspective: retrospective memory, or recalling experiences and facts from the past, and prospective memory, or realizing delayed intentions to be performed in the future (Brandimonte, Einstein, & McDaniel, 1996).
The complexity of human mnemonic function becomes evident when underlying theoretical models are analyzed. The formulation of a theoretical construct of memory is of great relevance to achieving a better understanding of clinical cases; however, it is not sufficient. The identification of the different types of memory deficits prevalent in a specific group, and the development of assessment instruments that provide reliable and valid information, have been a focus of attention among researchers and practitioners (Backman, Jones, Berger, Laukka, & Small, 2005; Soutor, Chen, Streisand, 2004).
Ruff and Schraa (2001) suggested that understanding the dichotomy between declarative and procedural (implicit) memory can be extremely useful in the context of rehabilitation. As procedural memory is frequently preserved when cognitive dysfunction occurs, intervention plans should consider strategies based on this preserved function and should utilize compensatory procedures to address declarative deficits (e.g. therapist names, times medication should be taken). The identification of problems in the audio-verbal or visuospatial modes of memory and learning can also provide useful information, as rehabilitation interventions could prioritize the preserved mode of processing and storing information.
As previously noted, assessment of memory in vocational rehabilitation is seldom conducted with clients without a diagnosed neurological disease. Individuals with a variety of disabilities that are not primarily neurological disorders may also present memory deficits that compromise rehabilitation outcomes (Backman, Jones, Laukka, & Small, 2005; DeLuca, Christodoulou, Diramond, Rosestein, Kramer, Ricker, et al., 2004; Soutor, Chen, & Streisand, 2004).
Individuals at Risk of Developing Memory Deficits
Among the groups of clients who may be at particular risk for memory deficits are those with alcohol and other drug abuse (AODA) problems, schizophrenia, and mental retardation. The present paper will focus on these three disability groups, as these types of disabilities are often seen in vocational rehabilitation programs, and a considerable amount of research about the neurocognitive deficits associated with these disabilities has been conducted.
Memory and Alcohol and Other Drug Abuse
The National Institute on Alcohol Abuse and Alcoholism's 2001-2002 epidemiological study reported that approximately 12.9% of the 18-44 age group could be considered to meet the DSM-IV diagnostic criteria for alcohol abuse (National Institute on Alcohol and Alcoholism, n. d.). Chronic alcohol consumption is related to anatomical changes, such as shrinkage of brain tissue and changes in the white matter microstructure (Sullivan, & Pfefferbaum, 2003). Individuals who abuse alcohol frequently present cognitive and motor deficits (Lezak, 1995; Selby, & Azrin, 1998). Neuropsychological assessment of persons with chronic alcoholism provided evidence of persistent deficits, even after a period of sobriety (Munro, Saxton, & Buttes, 2000; Sullivan, Fama, Rosenbloom, & Pfefferbaum, 2002).
Evidence of memory deficits in AODA. In the medical literature there is at least one well described alcohol related dementia, Wernicke-Korsakoff's syndrome (Victor, Adams, Collins, 1989). Korsakoff's syndrome is characterized by profound remote and anterograde memory impairment (Fama, Marsh, Sullivan, 2004). However, more subtle memory deficits have been recently described in groups with alcohol dependence (Bowden, 1990). Cermak (1990) reviewed a variety of studies that documented a high prevalence of memory deficits in individuals with chronic alcoholism. Premature cognitive aging was found to be common, with memory scores below same-aged controls....
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