واکنش عاطفی و آگاهی از عملکرد کار در بیماری آلزایمر

Lack of awareness about performance in tasks is a common feature of Alzheimer's disease. Nevertheless, clinical anecdotes have suggested that patients may show emotional or behavioural responses to the experience of failure despite reporting limited awareness, an aspect which has been little explored experimentally. The current study investigated emotional reactions to success or failure in tasks despite unawareness of performance in Alzheimer's disease. For this purpose, novel computerised tasks which expose participants to systematic success or failure were used in a group of Alzheimer's disease patients (n=23) and age-matched controls (n=21). Two experiments, the first with reaction time tasks and the second with memory tasks, were carried out, and in each experiment two parallel tasks were used, one in a success condition and one in a failure condition. Awareness of performance was measured comparing participant estimations of performance with actual performance. Emotional reactivity was assessed with a self-report questionnaire and rating of filmed facial expressions. In both experiments the results indicated that, relative to controls, Alzheimer's disease patients exhibited impaired awareness of performance, but comparable differential reactivity to failure relative to success tasks, both in terms of self-report and facial expressions. This suggests that affective valence of failure experience is processed despite unawareness of task performance, which might indicate implicit processing of information in neural pathways bypassing awareness.

Reduced awareness about cognitive deficits or illness, also termed anosognosia, is a common feature of Alzheimer's disease (AD) (Morris & Hannesdottir, 2004). This phenomenon has important implications for help seeking behaviour and treatment compliance (Patel & Prince, 2001), has a role in safety (Starkstein, Jorge, Mizrahi, Adrian, & Robinson, 2007) and contributes to caregiver burden (Seltzer, Vasterling, Yoder, & Thompson, 1997). Unawareness varies according to the object (Markova & Berrios, 2001), and, in the case of AD, can range from unawareness about the diagnosis and the condition itself to reduced awareness of deficits in specific abilities. One important aspect of unawareness in AD is impaired monitoring of performance during tasks, which affects direct evaluation of ability and may have a considerable impact on how an individual adapts to deficits and on their activities of daily living. Impaired monitoring of errors is common in AD, with evidence indicating that patients have difficulties detecting and correcting errors during everyday tasks (Bettcher et al., 2008 and Giovannetti et al., 2002). Ability to monitor performance in cognitive tests has also been shown to be affected in AD. For example, metamemory research (for a review, see Souchay, 2007) has indicated that patients have reduced awareness of their performance during memory tasks, with a tendency to overestimate functioning (e.g., Agnew and Morris, 1998, Clare, 2002, Correa et al., 1996 and Hannesdottir and Morris, 2007), although there can be normal levels of confidence judgements when recalling individual memory items (Backman and Lipinska, 1993 and Pappas et al., 1992). Unawareness of impairment can also be domain-specific, affecting some abilities but not others (e.g., Banks and Weintraub, 2008 and Barrett et al., 2005). In contrast, to the findings concerning explicit self-rating of performance, there is evidence, nevertheless, that AD patients may be responding to task failure through various forms of behavioural adaptation, which may or may not be associated with full awareness. For example, the adoption of driving restrictions is often done voluntarily by patients, and is not strongly associated with awareness about loss of function (Cotrell & Wild, 1999). In addition, there is recent evidence for implicit processing of the concepts associated with task failure. Specifically, Martyr et al. (2011) developed a dementia-related emotional Stroop task in which the time taken to colour name dementia-related (e.g., forgetful and lapse) versus neutral words was compared. Patients with dementia showed the same degree of processing bias, lengthening the time taken to read the dementia-related words, as a caregiver comparison group. This contrasted with markedly reduced awareness of neuropsychological condition, with no correlation between awareness and the Stroop effect. Because the emotional interference effect on such tasks are thought to occur at a pre-attentive processing level (Mogg et al., 1993 and Ohman et al., 2001) it has been concluded that the results may indicate implicit knowledge of the effects of dementia. Taken together, the dissociation between preserved reactivity and impaired awareness in response to failure can be considered evidence of implicit processing of performance or cognitive deficit. This notion has been incorporated in theoretical models of unawareness in dementia. For example, in the Cognitive Awareness Model (Agnew and Morris, 1998, Hannesdottir and Morris, 2007 and Morris and Hannesdottir, 2004) there is an implicit component that bypasses explicit awareness and produces behavioural and affective regulation. In summary, the above studies suggest that people with AD may be responsive to performance failure in the absence of reported awareness. This study was designed to explore this issue in AD further by investigating another indication of responsiveness during performance failure, namely emotional reactivity. For this purpose, we developed two novel experimental success-failure manipulation (SFM) paradigms in which we manipulated systematically levels of task difficulty to gain experimental control over the degree of success or failure, enabling the same levels of performance to be obtained on the tasks by patients and controls. Two paradigms were developed, one with a reaction time procedure and another with memory, in order to determine the extent to which results would generalise across types of task, with the two procedures selected on the basis that their difficulty level could more easily be titrated. Previous research has shown that emotional reactivity in early AD shows relative preservation; although identification of emotions may be impaired, for example in paradigms using facial expressions (McLellan et al., 2008), reactivity to affect-laden stimuli is preserved, as shown in studies employing pictures (Burton and Kaszniak, 2006 and Eling et al., 2006) and films (Henry et al., 2009 and Smith, 1995). It follows that the main prediction of the current study was that, despite showing markedly reduced reported awareness of performance levels, AD patients would show the same level of emotional responses, assessed by self-report and rating of filmed facial expressions, as control participants.