No clear associations between subjective memory concerns and subsequent change in cognitive function: the PATH through life study

The literature on subjective memory concerns (SMC) as a predictor for future cognitive decline is varied. Furthermore, recent research has pointed to additional complexity arising from variability in the experience of SMC themselves (i.e. whether they are remitting or sustained over time). We investigated the associations between SMC and objectively measured cognition in an Australian population-based cohort. Four waves (4-year intervals between waves) of data from 1236 participants (aged 62.4 ± 1.5 years, 53% male) were used. We categorized participants as experiencing SMC, when they indicated that their memory problems might interfere with their day-to-day life and/or they had seen a doctor about their memory. SMC was categorized as “no” reported SMC, “remitting”, “new-onset” or “sustained” SMC. Cognitive assessment of immediate and delayed recall, working memory, psychomotor speed, attention and processing speed were assessed using a neuropsychological battery. Eighteen percent of participants were characterised as having SMC: 6% (77) “remitting”, 6% (77) “new-onset” and 6% (69) “sustained” SMC. There was no consistent evidence for an association between SMC and subsequent decline in cognition. However, SMC was associated with poorer performance on contemporaneous tasks of attention and processing speed compared to “no” SMC. Asking about SMC may indicate a current decline in cognitive function but, in this sample at least, did not indicate an increased risk of future decline.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10433-022-00694-2.     

MIND not Mediterranean diet related to 12-year incidence of cognitive impairment in an Australian longitudinal cohort study

Introduction

Associations between the Mediterranean-DASH diet Intervention for Neurological Delay (MIND) diet and incidence of cognitive impairment have not been evaluated outside the United States.

On-Road Behavior in Older Drivers With Mild Cognitive Impairment

ObjectivesDementia increases the risk of unsafe driving, but this is less apparent in preclinical stages such as mild cognitive impairment (MCI). There is, however, limited detailed data on the patterns of driving errors associated with MCI. Here, we examined whether drivers with MCI exhibited different on-road error profiles compared with cognitively normal (CN) older drivers.DesignObservational.Setting and ParticipantsA total of 296 licensed older drivers [mean age 75.5 (SD = 6.2) years, 120 (40.5%) women] recruited from the community.MethodParticipants completed a health and driving history survey, a neuropsychological test battery, and an on-road driving assessment including driver-instructed and self-navigation components. Driving assessors were blind to participant cognitive status. Participants were categorized as safe or unsafe based on a validated on-road safety scale, and as having MCI based on International Working Group diagnostic criteria. Proportion of errors incurred as a function of error type and traffic context were compared across safe and unsafe MCI and CN drivers.ResultsCompared with safe CN drivers (n = 225), safe MCI drivers (n = 45) showed a similar pattern of errors in different traffic contexts. Compared with safe CN drivers, unsafe CN drivers (n = 17) were more likely to make errors in observation, speed control, lane position, and approach, and at stop/give-way signs, lane changes, and curved driving. Unsafe MCI drivers (n = 9) had additional difficulties at intersections, roundabouts, parking, straight driving, and under self-navigation conditions. A higher proportion of unsafe MCI drivers had multidomain subtype [n = 6 (67%)] than safe MCI drivers [n = 11 (25%)], odds ratio 6.2 (95% confidence interval, 1.4–29.6).Conclusion and ImplicationsAmong safe drivers, MCI and CN drivers exhibit similar on-road error profiles, suggesting driver restrictions based on MCI status alone are unwarranted. However, formal evaluation is recommended in such cases, as there is evidence drivers with multiple domains of cognitive impairment may require additional interventions to support safe driving.     

The role of spatial location in auditory search

The majority of research findings to date indicate that spatial cues play a minor role in enhancing listeners' ability to parse and detect a sound of interest when it is presented in a complex auditory scene comprising multiple simultaneous sounds. Frequency and temporal differences between sound streams provide more reliable cues for scene analysis as well as for directing attention to relevant auditory 'objects' in complex displays. The present study used naturalistic sounds with varying spectro-temporal profiles to examine whether spatial separation of sound sources can enhance target detection in an auditory search paradigm. The arrays of sounds were presented in virtual auditory space over headphones. The results of Experiment 1 suggest that target detection is enhanced when sound sources are spatially separated relative to when they are presented at the same location. Experiment 2 demonstrated that this effect is most prominent within the first 250 ms of exposure to the array of sounds. These findings suggest that spatial cues may be effective for enhancing early processes such as stream segregation, rather than simply directing attention to objects that have already been segmented.     

Spatial gradient for unique-feature detection in patients with unilateral neglect: Evidence from auditory and visual search

Patients with unilateral spatial neglect following right hemisphere damage are impaired in detecting contralesional targets in both visual and haptic search tasks, and often show a graded improvement in detection performance for more ipsilesional spatial locations. In audition, multiple simultaneous sounds are most effectively perceived if they are distributed along the frequency dimension. Thus, attention to spectro-temporal features alone can allow detection of a target sound amongst multiple simultaneous distracter sounds, regardless of whether these sounds are spatially separated. Spatial bias in attention associated with neglect should not affect auditory search based on spectro-temporal features of a sound target. We report that a right brain damaged patient with neglect demonstrated a significant gradient favouring the ipsilesional side on a visual search task as well as an auditory search task in which the target was a frequency modulated tone amongst steady distractor tones. No such asymmetry was apparent in the auditory search performance of a control patient with a right hemisphere lesion but no neglect. The results suggest that the spatial bias in attention exhibited by neglect patients affects stimulus processing even when spatial information is irrelevant to the task.     

Association between auditory and visual symptoms of unilateral spatial neglect

Unilateral spatial neglect due to right brain damage (RBD) can occur in several different sensory modalities in the same patient. Previous studies of the association between auditory and visual neglect have yielded conflicting outcomes. Most such studies have compared performance on relatively simple clinical measures of visual neglect, such as target cancellation, with that on more sophisticated measures of auditory perception. This is problematic because such tasks are typically not matched for the cognitive processes they exercise. We overcame this limitation by using equivalent visual and auditory versions of extinction and temporal-order judgment (TOJ) tasks. RBD patients demonstrated lateralized deficits on both visual and auditory tasks when compared with same-aged, healthy controls. Critically, a significant association between the severity of visual and auditory deficits was apparent on the TOJ task but not the extinction task, suggesting that even when task demands are matched across modalities, dissociations between visual and auditory neglect can be apparent. Across the auditory tasks, patients showed more pronounced deficits for verbal stimuli than for non-verbal stimuli. These findings have implications for recent models proposed to explain the role of spatial attention in multimodal perception.     

Effects of prismatic adaptation on spatial gradients in unilateral neglect: A comparison of visual and auditory target detection with central attentional load

Prismatic adaptation is increasingly recognised as an effective procedure for rehabilitating symptoms of unilateral spatial neglect - producing relatively long-lasting improvements on a variety of spatial attention tasks. The mechanisms by which the aftereffects of adaptation change neglect patients’ performance on these tasks remain controversial. It is not clear, for example, whether adaptation directly influences the pathological ipsilesional attention bias that underlies neglect, or whether it simply changes exploratory motor behaviour. Here we used visual and auditory versions of a target detection task with a secondary task at fixation. Under these conditions, patients with neglect demonstrated a spatial gradient in their ability to orient to the brief, peripheral visual or auditory targets. Following prism adaptation, we found that overall performance on both the auditory and visual task improved, however, most patients in our sample did not show changes in their visual or auditory spatial gradient of attention, despite adequate aftereffects of adaptation and significant improvement in neglect on visual cancellation. Although there were individual cases that suggested prism-induced changes in visual target detection, and even reversal of the visual spatial gradient, such cases were not evident for the auditory modality. The findings indicate that spatial gradients in stimulus-driven attention may be less responsive to the effects of prism adaptation than neglect symptoms in voluntary orienting and exploratory behaviour. Individual factors such as lesion site and symptom severity may also determine the expression of prism effects on spatial neglect.