Patterns of cognitive ageing

Abstract

Neuroanatomical evidence suggests that normal ageing affects some brain areas, and the "local" functions they support, earlier and more severely than others. Changes appear to be especially marked in the hippocampus, temporal association and prefrontal cortex. Evidence from classical neuropsychological studies suggests that these brain areas are associated with memory and "executive" functions, respectively. We may, therefore, expect that tests purported to measure these functions may be disproportionately affected in old age and that there may be evidence for some separation of these functions even within neurologically normal populations. What we also know, however, is that measures reflecting general fluid ability also decline with increasing age, so any hypothesis relating to specific "local" deficits must acknowledge and account for any "globar" changes in performance. Volunteers (n = 162) aged between 60-80 years who had completed the Cattell and Cattell Culture Fair Intelligence Test (CCF) completed the Cambridge Automated Neuropsychological Test Battery (CANTAB). The CANTAB has been administered to several patient populations and tests from the battery have been shown to be sensitive to damage in both temporal and prefrontal areas (Owen et al., 1996). Results from the test battery showed that both the Paired Associate Learning and Spatial Recognition tests were the most sensitive to normal ageing even when CCF is accounted for. In contrast, this performance on the "executive" tests, shown to be sensitive to frontal lobe damage was not related to age, and CCF scores predicted performance on these tests. These results are discussed in relation to theories of cognitive ageing and patterns of change and in relation to several important methodological and theoretical considerations for the study of executive function.

Differential muscarinic and NMDA contributions to visuo-spatial paired-associate learning in rhesus monkeys

“…In summary, previous observations from studies of visuo-spatial paired-associates learning in elderly and AD human populations have suggested that this nonverbal task may offer improved specificity for identifying age-related cognitive dysfunction (Fowler et al 1997;Rabbitt and Lowe 2000;Robbins et al 1994;Swainson et al 2001). The results of the present study demonstrate that rhesus monkeys perform the task in a manner analogous to humans and that their performance is disrupted by administration of scopolamine in a manner consistant with previous anticholinergic models of memory disruption.…”

“…The task involves learning to associate visual stimuli with distinct spatial locations on a trial-by-trial basis, performance of which has been demonstrated to decline with age in large-sample factor analytic studies (Rabbitt and Lowe 2000;Robbins et al 1994). Sahakian and colleagues have further demonstrated impaired performance of vsPAL in AD patients relative to age-and premorbid IQ-matched controls, and recognition-memory impaired Parkinson's patients (Sahakian et al 1990;Sahakian et al 1988;Sahgal et al 1991).…”

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

“…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.…”

Thalamic functional connectivity and its association with behavioral performance in older age

“…Our results highlight that advanced age was associated with poorer performance on a visual–spatial memory task, as has been shown previously (Hayat et al., 2014; Lee, Archer, Wong, Chen, & Qiu, 2013; Rabbitt & Lowe, 2000). In addition, we provide evidence that, although visual–spatial memory performance was not directly correlated with thalamo‐hippocampal FC, older poor memory performers exhibited significantly greater thalamo‐right hippocampal FC compared to both younger adults and older good memory performers.…”