Cognitive plasticity as a modulating variable on the effects of memory training in elderly persons

Archives of Clinical Neuropsychology 22 (2007) 63–72 Cognitive plasticity as a modulating variable on the effects of memory training in elderly persons M. Dolores Calero ∗ , Elena Navarro Accepted 12 June 2006 Abstract Cognitive plasticity is a topic of interest since it allows us to analyse the potential cognitive modifiability of a person. Previous research has demonstrated the existence of plasticity in old age [Baltes, P. B. (1987). Theoretical propositions of life-span developmental psychology: On the dynamics between growth and decline. Developmental Psychology, 23(5), 611–626] regardless of presence or absence of cognitive deterioration [Calero, M. D., & Navarro, E. (2004). Relationship between plasticity, mild cognitive impairment and cognitive decline. Archives of Clinical Neuropsychology, 19, 653–660]. In this context, the present study was designed to analyse the presence of plasticity in elderly persons who seemed to present cognitive deterioration, and to explore the relation between cognitive plasticity and the results obtained from a memory training programme. One hundred and thirty-three elderly persons participated in the study and were evaluated by means of a cognitive plasticity test (Position test) and various tests for measuring the effects of the training. Part of the elderly population received the memory training, whose effects were measured immediately after the training and again after 9 months. The results demonstrate that the programme significantly improves cognitive performance, while plasticity is shown to be an important modulating variable on the improvement achieved. © 2006 National Academy of Neuropsychology. Published by Elsevier Ltd. All rights reserved. Keywords: Cognitive plasticity; Memory training; Old age; Cognitive impairment; Position test 1. Introduction The aging process is often associated with the existence of cognitive decline, which is dependent on both environmental and physiological factors. Numerous researchers have demonstrated that this decline is not uniform, since the patterns of change present wide intra- and interindividual variability (Baltes, 1987; Baltes, Dittmann-Kohli, & Dixon, 1984; Schaie, 1990). When analysing interpersonal variability, an important distinction is drawn between present performance (a person’s observable execution in a specific situation) and potential performance (the execution which the person could achieve if alternative optimizing conditions were considered or introduced). This distinction allows researchers to analyse the potential cognitive modifiability of a person rather than only taking into account the score of a standard cognitive performance test (Baltes & Willis, 1982). By ‘potential cognitive modifiability’ we refer to the cognitive reserve or ability of a person to optimize or maximize his or her performance by activating compensatory mechanisms (Stern, 2002). Thus, as Singer, Lindenberger, and Baltes (2003) explain, in behaviorally oriented ∗ Corresponding author at: Facultad de Psicologı́a, Universidad de Granada, Campus La Cartuja, 18071 Granada, Spain. Tel.: +34 58 243754; fax: +34 58 243749. E-mail address: (M.D. Calero). 0887-6177/$ – see front matter © 2006 National Academy of Neuropsychology. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.acn.2006.06.020 Department of Personality, Psychological Assessment and Treatment, Faculty of Psychology, University of Granada, Spain 64 M.D. Calero, E. Navarro / Archives of Clinical Neuropsychology 22 (2007) 63–72 cognitive aging research, cognitive plasticity or within-person variability refers to learning gain (pre-test–post-test difference score) as indicated by levels of performance after instruction and practice in performance-enhancing skills. The existence of such modifiability has been labelled ‘cognitive plasticity’ by Baltes and Willis (1982), who define it as intellectual performance in old age under optimizing conditions which do not normally exist in the day-to-day life of the person. Research undertaken over the last 20 years has further demonstrated that it is possible to improve cognitive performance in later adulthood (Verhaeghen, 2000). In order to evaluate modifiability, Baltes and his team developed a procedure for ‘testing the limits’ (Baltes et al., 1984), also known in Spain and other countries as ‘evaluation of learning potential’ (Calero, 1995). Following the ‘pretest-training–post-test’ evaluation format, the procedure consists of a traditional evaluation test in two temporal phases (initial and subsequent test) with an intermediate training phase in which the subject is shown the necessary strategies to complete the task successfully. The capacity to benefit from the training (pre-test–post-test difference) provides a measure of the person’s cognitive plasticity (Baltes & Baltes, 1997; Calero, Navarro, Arnedo, Garcı́a-Berbén, & Robles, 2000a). In their initial studies, Paul Bates and his team focused on demonstrating the existence of plasticity. Later the objective shifted to establishing its limits, and finally Margaret Baltes and colleagues began to study the relation between plasticity and deterioration (Baltes, Kuhl, & Sowarka, 1992; Baltes, Kuhl, Sowarka, & Gutzman, 1995). In the Spanish population, studies carried out by the Baltes team with regard to the existence of plasticity in healthy elderly persons have been replicated (Fernández-Ballesteros & Calero, 1995; Calero & Garcı́a-Berbén, 1997). In recent years, the analysis of the relation between plasticity and cognitive deterioration has formed a new line of research (Calero & Navarro, 2004; Fernández-Ballesteros, Zamarrón, Tárraga, Moya, & Iñiguez, 2003), together with the analysis of the relation between cognitive plasticity and results obtained by elderly persons in extended memory training programmes. The present study has been carried out as part of this second line of research. The effectiveness of memory training programmes in old age has been amply demonstrated in various meta-analyses which show that participation significantly improves both objective memory (Verhaeghen, Marcoen, & Goossens, 1992) and subjective memory, i.e. the perception that the person has of his or her own memory performance (Floyd & Scogin, 1992). Similarly, it has been shown that the improvement achieved after participating in memory training programmes may be maintained for periods of time ranging from 6 months (Bäckman, 1995; Stigsdotter-Neely & Bäckman, 1995) up to 3 years (Scogin & Bienias, 1988; see Verhaeghen, 2000 for a review of this topic). At the same time, various studies have focused on demonstrating the relation between diverse personal and/or psychological variables and the improvement achieved by the elderly persons after cognitive training. Prominent among these variables are aspects such as age (Baltes, Dittmann-Kohli, & Kliegl, 1986), verbal ability (Yesavage, Sheikh, Decker, & Hill, 1988), mental status (...truncated)