Cognitive load of walking in people who are blind: Subjective and objective measures for assessment.

BACKGROUND: Although walking without vision seems to carry a high cognitive cost, few studies have measured the cognitive load involved in this activity in blind people. The aim of this study was to assess the cognitive load of walking in blind people, using gait analysis, a dual task paradigm and a subjective assessment of cognitive load. METHODS: In a quantitative quasi-experimental design, 25 blind adults walked 40 meters. In one trial, participants walked normally (control condition). In another, they walked while performing an auditory simple reaction time task, and in the third trial they walked, performed the simple reaction time task and avoided obstacles. In addition to the simple reaction time task performance, walking speed was recorded, and participants provided a subjective assessment of cognitive load after each trial. Performance of participants aged less than 60 years were compared with those aged over than 60 years. RESULTS: Walking significantly reduced performance of the simple reaction time task; carrying out the simple reaction time task while walking significantly reduced walking performance and increased the subjective assessment of cognitive load; and simple reaction time task performance decreased and subjective assessment increased when obstacles were present. Few significant age effects were found. SIGNIFICANCE: Walking without vision involves a cognitive load that increases when the environment becomes complex. Each of the three methods used is relevant when assessing the cognitive load involved in walking in blind people, and could be useful in rehabilitation intervention. The results obtained allowed recommendations to be suggested for the design of technological mobility devices.

Ageing effects on the attentional capacities and working memory of people who are blind.

PURPOSE: Adaptation to blindness can lead to the enhancement of the attentional capacities and working memory in young people. However, although the effects of ageing on the cognition of sighted people and people with age-related visual impairments are well-documented, no study seems to have investigated the age-related changes of these cognitive processes in people who are blind. The aim of this study was to assess the effects of age on the attentional processes and working memory in blind people. METHOD: A cross-sectional study was conducted on 43 blind participants and 42 sighted participants. The participants performed auditory computerized tests assessing selective, sustained and divided attention, attentional switching, and working memory. RESULTS: Two-way analysis of variance revealed significant visual status effect and age effect on most of the variables studied. No interaction was found between visual status and age effects. CONCLUSIONS: These results suggest that the trajectories of cognitive age-related change are similar in blind people and in sighted people. This study has implications for rehabilitation, such as cognitive intervention. Implications for Rehabilitation Blind people show improved attentional capacities compared to sighted people, even in old blind people. Old blind people have lower performances than younger blind people in tests assessing selective, sustained and divided attention, and working memory. Cognitive approaches to rehabilitation may help people who are blind to deal with age-related cognitive decline and its effects on everyday functioning. A high level of cognitive stimulation, provided by a cognitive training or a developed social participation, might reduce the age-related effects in people who are blind.

The role of navigation instruction at intersections for older drivers and those with early Alzheimer's disease.

AIMS: Our purpose was to explore the effect of navigation instruction on older drivers' driving performance at left turn intersections. Left turns at intersections are particularly complex because they require many perceptive and cognitive abilities under considerable time pressure. METHODS: Fifty-four participants were recruited: 18 drivers with early-stage Alzheimer's disease (AD), 18 neurologically healthy older drivers and 18 younger individuals. Various cognitive processes were measured, and 9 left turn maneuvers with or without navigation instruction were evaluated during an in-traffic road test. The psychomotor, planning and decision-making components involved in left turn were also analyzed closely. RESULTS: Only older drivers (both healthy drivers and those with AD) were negatively affected by navigation instruction during the maneuver. The planning and decision-making components were more likely to be affected by the navigation instruction. CONCLUSION: This finding highlights the importance of carefully considering the use of navigation instructions when developing navigation systems. Adapting this instruction is necessary to simplify our understanding of the real-world driving environment and to avoid increasing the cognitive load of older drivers.

Evaluation of the attentional capacities and working memory of early and late blind persons.

Although attentional processes and working memory seem to be significantly involved in the daily activities (particularly during navigating) of persons who are blind and who use these abilities to compensate for their lack of vision, few studies have investigated these mechanisms in this population. The aim of this study is to evaluate the selective, sustained and divided attention, attentional inhibition and switching and working memory of blind persons. Early blind, late blind and sighted participants completed neuropsychological tests that were designed or adapted to be achievable in the absence of vision. The results revealed that the early blind participants outperformed the sighted ones in selective, sustained and divided attention and working memory tests, and the late blind participants outperformed the sighted participants in selective, sustained and divided attention. However, no differences were found between the blind groups and the sighted group in the attentional inhibition and switching tests. Furthermore, no differences were found between the early and late blind participants in this set of tests. These results suggest that early and late blind persons can compensate for the lack of vision by an enhancement of the attentional and working memory capacities.

Impaired updating ability in drivers with Parkinson's disease.

OBJECTIVE: Driving activity requires major involvement of executive functions. The main objective of our study was to determine whether mental flexibility and the updating of information in working memory are affected in drivers with mild to moderate Parkinson's disease (PD). METHODS: The study included 25 patients, aged 58-76, with mild to moderate PD and 25 healthy controls matched for age, sex and education, with an average mileage of over 3000 km/year. Neuropsychological tests were conducted to assess global cognitive abilities, to evaluate updating (via the n-back task), flexibility (via the plus-minus task) and information-processing speed (via the Stroop test). Three different scenarios were developed on a driving simulator. Participants were asked to recall road signs (updating task), indicate the shape or colour of road signs according to road side (flexibility task) and to brake at the same time as the car ahead (information-processing speed task) while driving. RESULTS: An updating impairment was found in PD patients in the n-back and simulator tasks; patients recalled significantly fewer road signs. No notable differences were observed between groups in the plus-minus task or in the simulator task evaluating flexibility. There was no significant difference between patients and controls in information-processing speed tasks. Regression analysis showed that the Trail-Making test (B-A) accounted for 40.7% of the variation in PD drivers' simulator task updating score. CONCLUSION: The updating function is clearly impaired in drivers with mild to moderate PD, while mental flexibility remains unaffected. This study demonstrates the interest of using the Trail Making Test and simulator tasks to assess PD drivers.

The Wechsler Digit Symbol Substitution Test as the best indicator of the risk of impaired driving in Alzheimer disease and normal aging.

AIMS: Our purpose was to identify cognitive tools associated with unsafe driving among elderly drivers of varying cognitive levels. METHODS: Twenty drivers with early-stage dementia of the Alzheimer type and 56 nondemented drivers aged 65-85 were recruited. Various cognitive processes were measured and unsafe driving was evaluated during an in-traffic road test with 3 different indicators and a composite indicator. RESULTS: The Wechsler Digit Symbol Substitution Test score was the best cognitive measure to detect unsafe drivers using the composite driving indicator. CONCLUSION: The Digit Symbol Substitution Test may be used by physicians for the evaluation and follow-up of older patients, with or without Alzheimer-type dementia, as a screening tool of unsafe driving.