An experiment is reported in which young and older adults performed a visual orienting task and a cue discrimination task. In the visual orienting task symbolic cues (letters) provided predictive information concerning the likely location of a target stimulus. Two letters, drawn from a pool of four ‘valid’ and four ‘invalid’ letters, were presented bilaterally, at either central or peripheral locations. In the cue discrimination task participants were presented with the same bilateral letter stimuli, and indicated whether these represented a valid letter on the right with an invalid letter on the left, or vice versa. In the visual orienting task young adults shifted attention appropriately in response to the letter cues, but older adults failed to do this. Older participants also performed more poorly on the cue discrimination task. However, even older participants who performed as well as young participants on the cue discrimination task failed to orient in response to the letter cues. Results are discussed in terms of effects of ageing on the ability to forge functionally effective links between different task components in the course of learning how to perform new perceptuomotor skills.

The present investigation aimed to assess whether a generalised inhibitory breakdown (Hasher & Zacks, 1988) can account for the well-documented age-related episodic memory deficits. It was argued that, according to whether significant correlations were found among all or between some of the measures of episodic memory and of inhibition included in the present investigation, it would be possible to assume that either a general or a specific, for instance, frontal lobe dependent inhibitory deficit (Dempster, 1992), was responsible for age-related memory deficit. At an empirical level, results from this investigation complement the large number of studies indicating an episodic memory deficit and an early deterioration of frontal lobes in the elderly. At a theoretical level, however, the failure to find age-related differences in the negative priming task challenges the hypothesis that cognitive ageing is due to a generalised inhibitory deficit. Furthermore, the failures to find significant correlations among performance on different tasks assumed to reflect the operation of inhibition processes support the hypothesis for the existence of multiple dissociable inhibitory processes (e.g., Kramer, Humphrey, Larish, Logan, and Strayer, 1994).

Within the experimental literature there is substantial evidence of larger age-related deficits in retrieving source information relative to item-based information. However, this evidence is potentially subject to methodological criticism given that several studies have argued for the presence of source-monitoring deficits by examining source memory contingent on correct recall of item information but not the reverse. In order to address this potential shortcoming our study examines recall of both item information contingent on correct source judgement and source-based information contingent on correct recall of item information. We demonstrate that when this novel type of analysis is conducted, there are age deficits for both source and item information, and no evidence of a selectively greater source-monitoring deficit in the elderly. The results are discussed with reference to two overarching theoretical positions concerning age-related deficits in memory performance.

Considerable research has been devoted to the issue of whether the ingestion of glucose enhances cognitive performance in both younger and older adults. However, it has proven difficult to draw firm conclusions from this literature due to the diversity of methodologies that have been used, and it is therefore still unclear what factors might moderate the facilitative effect. The present study investigates methodological variations and their impact on the magnitude of the glucose enhancement effect. In particular, age group (young vs. old) and task domain (memory vs. nonmemory tasks) were considered as moderator variables. In addition, differences in experimental design, glucose dose and fasting regime were examined. The effect size d was extracted from studies comparing cognitive performance after the ingestion of either a glucose or control solution. Subsequent meta-analyses were conducted (using the procedures outlined by Hedges & Olkin, 1985) to examine potential moderators. A moderate overall effect size was found (d = 0.56), which clearly demonstrated the value of glucose ingestion as a cognitive enhancer. However, this effect size was not representative of the 104 individual effect sizes reported. Secondary analyses found larger effect sizes for memory compared to nonmemory tasks. Unexpectedly, no evidence was provided for greater beneficial effects of glucose on cognitive performance for older compared to younger adults. The impact of other methodological variables and the need for further exploration in an elderly population are discussed.

The potential role of supplementing sex steroids for the prevention and delay of age-related cognitive decline has received a great deal of recent interest. Although the biological plausibility of hormone treatment has received considerable support, clinical studies of cognitive functioning after hormonal treatment in postmenopausal women with and without dementia have produced mixed results. Much less attention has been given to the corresponding role of androgens in men. In order to establish the relevance of hormonal supplementation for men in delaying or preventing cognitive decline, it is of importance to evaluate both adrenal and gonadal contributions to androgen status. Additionally, consideration must also be given to the potential interactions of androgens with risk and protective factors (e.g., apolipoprotein E genotype and education). Here we review experimental and epidemiological studies of the significance of androgens for cognitive function.

Qualitative aspects of verbal fluency may be more useful in discerning the precise cause of any quantitative deficits in phonetic or category fluency, especially in the case of mild cognitive impairment (MCI), a possible intermediate stage between normal performance and Alzheimer's disease (AD). The aim of this study was to use both quantitative and qualitative (switches and clusters) methods to compare the phonetic and category verbal fluency performance of elderly adults with no cognitive impairment (n = 51), significant memory impairment (n = 16), and AD (n = 16). As expected, the AD group displayed impairments in all quantitative and qualitative measures of the two fluency tasks relative to their age- and education-matched peers. By contrast, the amnestic MCI group produced fewer animal names on the semantic fluency task than controls and showed normal performance on the phonetic fluency task. The MCI group's inferior category fluency performance was associated with a deficit in their category-switching rate rather than word cluster size. Overall, the results indicate that a semantic measure such as category fluency when used in conjunction with a test of episodic memory may increase the sensitivity for detecting preclinical AD. Future research using external cues and other measures of set shifting capacity may assist in clarifying the origin of the amnestic MCI-specific category-switching deficiency.

The present study investigated the relationship between anosognosia for cognitive, functional and psychopathological disorders in Alzheimer's disease (AD) and vascular dementia (VD). Ten patients with probable Alzheimer's disease and 10 patients with probable vascular dementia were matched for age, education, illness duration and dementia severity. Cognitive, functional and psychopathological characteristics of the patients were assessed by means of different self-rating scales. The same questionnaires were submitted to patients' caregivers, blind to the patients' answers. Anosognosia was defined as the positively signed difference between patients' and caregivers' ratings. Three anosognosia indices for each domain investigated were obtained. We found lack of insight to be a common and consistent feature of AD and VD. However, unawareness for cognitive and functional domains was more severe in AD than in VD. Furthermore, in AD patients anosognosia for cognitive, functional and psychopathological domains dissociated from one another, as shown by lack of significant correlations between the three indices. Conversely, in VD patients these three anosognosic domains were closely related, indicating a generalised unawareness. These findings suggest that heterogeneity of anosognosic deficits may help differentiate AD from VD.