Diminished curiosity in patients with probable Alzheimer's disease as measured by exploratory eye movements

Abstract

Clinical accounts of Alzheimer's disease (AD) suggest that some patients exhibit markedly diminished curiosity and initiative early in the course of their illness. Such behavioral changes are extremely difficult to measure experimentally. We studied one aspect of curiosity by measuring exploratory eye movements in response to provocative visual stimuli in 12 patients with probable AD and 10 matched controls. Subjects viewed slides, each of which contained an incongruous or irregular figure paired with a congruous or regular one. Unlike controls, who spent significantly more time viewing the incongruous stimuli, AD patients distributed their viewing time equally and spent significantly less time than controls looking at the novel stimuli. Additionally, when presented with picture slides containing an unexpected element, AD patients exhibited diminished visual exploration overall and decreased attention to the incongruous part. Further analyses suggest that the results cannot be adequately explained by a general decline in cognition or by problems with ocular motility or directing visual attention. We conclude that AD patients exhibit diminished curiosity which can be measured by the study of exploratory eye movements.

Emotional curiosity: modulation of visuospatial attention by arousal is preserved in aging and early-stage Alzheimer’s disease

“…The findings are in contrast to our previous report in which PRAD patients were impaired in modulating visual exploration according to variations in the novelty and complexity of emotionally-neutral stimuli using a task design similar to the one in the present study [4]. This dissociation probably reflects differences in the pathological vulnerability of the neural networks that subserve novelty-seeking behaviors versus those that subserve orientation to arousing stimuli.…”

“…As discussed above, they fail to show a preferential viewing of novel events [4]. Furthermore, they have difficulty covertly shifting attention to targets at different spatial locations, especially in the presence of distracters or when attention has first been cued to a location that is different from the one at which the target actually appears [23].…”

“…An alternative explanation may be based on differences in dementia severity. To address this possibility, we converted the MMSE scores from the sample in the present study to Blessed Dementia Scale (BDS) scores on the same scale as that used by Daffner et al [4]. The MMSE and BDS are highly correlated scores of dementia severity and can be converted to one another [6,26,27].…”

“…However, the adaptive deployment of attention to extrapersonal events is also frequently disrupted early in the course of the disease and interferes with activities of daily living. These attentional deficits are multifaceted and include altered visual search strategies [8,22,24], an inability to disengage the focus of attention [20,23] and reduced orientation to novel and complex stimuli [4]. Furthermore, while AD patients may be able to focus attention globally or locally when each mode is tested in a separate experiment, they have difficulty when required to switch between these processing modes in the same block of experimental trials [7].…”

The apolipoprotein E gene, attention, and brain function.

“…For example, whereas AD patients show an attentional-shifting deficit in both tasks, PD patients show a deficit in the maintenance of attention across trials in both tasks (see Filoteo et al, 1995 for a review). This consistency also mirrors the disparate pathologies and neurochemical deficits characterizing PD and AD.Finally, the deficit in covert attention shifting in AD patients is also reflected in deficits in overt shifts of attention (Daffner, Scinto, Weintraub, & Mesulam, 1992;Rosler et al, 2000;Scinto, Daffner, Castro, & Mesulam, 1994 (2000) found reduced right parietal activation in AD patients, consistent with the PET and SPECT; findings of right parietal hypometabolism associated with covert attention (Buck et al, 1997;Parasuraman et al, 1992). Individuals with AD are also impaired in making antisaccades; that is, eye movements in a direction opposite to that of a peripheral stimulus with sudden onset (Fletcher & Sharpe, 1988).…”