Electrophysiological and information processing variability predicts memory decrements associated with normal age-related cognitive decline and Alzheimer's disease (AD)

Abstract

Recent theoretical models of cognitive aging have implicated increased intra-individual variability as a critical marker of decline. The current study examined electrophysiological and information processing variability and memory performance in normal younger and older controls, and older adults with Alzheimer's disease (AD). It was hypothesized that higher levels of variability would be indicative of age-related and disease-related memory deficits. Results indicated both implicit and explicit memory deficits associated with AD. There is a great deal of controversy regarding the predictive validity of standard neuropsychological assessments in identifying early cases of dementia (Ritchie and Lovestone, 2002;Ritchie and Touchon, 1992) and the underlying causal factors associated with age-and disease-related decrements in memory and cognition (Anderson and Craik, 2000;Grady and Craik, 2000;Hogan, 2004;Hogan et al., 2003). Theoretical models of neurological aging have implicated increased intra-individual variability as a marker of generalized cognitive decline (Li and Lindenberger, 1998). A number of studies have examined intra-individual variability in older adults using measures of reaction time (Hogan, 2003;Myerson and Hale, 1993;Myerson et al., 1990;Rabbitt and Lowe, 2000;Salthouse, 1993), sensorimotor ability (Li et al., 2001), and cognitive ability (Hertzog et al., 1992;Hultsch et al., 2002). Results support the conclusion that levels of intra-individual variability increase with advancing age.

Within-person trial-to-trial variability precedes and predicts cognitive decline in old and very old age: Longitudinal data from the Berlin Aging Study

“…The main finding of a dynamic influence of variability on mean cognitive performance levels is consistent with findings indicating that cognitive variability predicts chronological age (e.g., Hultsch et al, 2002), cognitive functioning (e.g., Hultsch et al, 2000), and disease status (e.g., Fuentes et al, 2001;Hogan et al, 2006;see Hultsch & MacDonald, 2004;MacDonald et al, 2006, for reviews) independently of central tendency. However, the finding is inconsistent with recent results reported by Salthouse and Berish (2005).…”

Characterising neural signatures of successful aging: Electrophysiological correlates of preserved episodic memory in older age

“…The task was based on a modified version of Hogan et al (2006). The task specification are outlined below.…”

Neuromodulation and aging: implications of aging neuronal gain control on cognition

“…Of particular clinical relevance, older adults Neuromodulation of cognitive aging Li and Rieckmann 151 who exhibited more short-term moment-to-moment RT fluctuations showed steeper longitudinal declines over 13 years in the category fluency task that, in part, demands executive control [42]. Moreover, psychophysiological measures of neuronal variability during executive control that are derived from electroencephalogram (EEG), such as greater amplitude variability of the P300 evoked brain potential [43] or lower theta inter-trial phase coherence [44], showed increased variability in older adults and AD patients as compared to healthy controls. A lower level of EEG phase coherence across trials partly reflects temporal 'jitters' in neuronal activity, which is in turn associated with higher trial-to-trial RT fluctuation at the performance level (Figure 3c).…”