Visual Acuity does not Moderate Effect Sizes of Higher-Level Cognitive Tasks

Association of Vision Impairment With Cognitive Decline Across Multiple Domains in Older Adults

IMPORTANCE

Associations between visual and global cognitive impairments have been previously documented, but there is limited research examining these associations between multiple measures of vision across cognitive domains.

OBJECTIVE

To examine the association between vision and cognitive across multiple cognitive domains using multiple measures of vision.

DESIGN, SETTING, AND PARTICIPANTS

This longitudinal cohort study used data from the Baltimore Longitudinal Study of Aging for 2003 to 2019. Participants in the current study were aged 60 to 94 years with vision and cognitive measures. Data analysis was performed from May 2020 to May 2021.

MAIN OUTCOMES AND MEASURES

Cognitive function was measured across multiple domains, including language, memory, attention, executive function, and visuospatial ability. Cognitive domain scores were calculated as the mean of standardized cognitive test scores within each domain. Visual function was assessed using measures of visual acuity, contrast sensitivity, and stereo acuity at baseline.

RESULTS

Analyses included 1202 participants (610 women [50.8%]; 853 White participants [71.0%]) with a mean (SD) age of 71.1 (8.6) years who were followed up for a mean (SD) of 6.9 (4.7) years. Worse visual acuity (per 0.1 logarithm of the minimal angle of resolution) at baseline was associated with greater declines in language (β, -0.0035; 95% CI, -0.007 to -0.001) and memory (β, -0.0052; 95% CI, -0.010 to -0.001) domain scores. Worse contrast sensitivity (per 0.1 log units) at baseline was associated with greater declines in language (β, -0.010; 95% CI, -0.014 to -0.006), memory (β, -0.009; 95% CI, -0.015 to -0.003), attention (β, -0.010; 95% CI, -0.017 to -0.003), and visuospatial ability (β, -0.010; 95% CI, -0.017 to -0.002) domain scores. Over the follow-up period, declines on tests of language (β, -0.019; 95% CI, -0.034 to -0.005) and memory (β, -0.032; 95% CI, -0.051 to -0.012) were significantly greater for participants with impaired stereo acuity compared with those without such impairment.

CONCLUSIONS AND RELEVANCE

These findings suggest that the association between vision and cognition differs between visual acuity, contrast sensitivity, and stereo acuity and that patterns of cognitive decline may differ by type of vision impairment, with impaired contrast sensitivity being associated with declines across more cognitive domains than other measures of visual functioning.

Salience-based object prioritization during active viewing of naturalistic scenes in young and older adults

Whether fixation selection in real-world scenes is guided by image salience or by objects has been a matter of scientific debate. To contrast the two views, we compared effects of location-based and object-based visual salience in young and older (65 + years) adults. Generalized linear mixed models were used to assess the unique contribution of salience to fixation selection in scenes. When analysing fixation guidance without recurrence to objects, visual salience predicted whether image patches were fixated or not. This effect was reduced for the elderly, replicating an earlier finding. When using objects as the unit of analysis, we found that highly salient objects were more frequently selected for fixation than objects with low visual salience. Interestingly, this effect was larger for older adults. We also analysed where viewers fixate within objects, once they are selected. A preferred viewing location close to the centre of the object was found for both age groups. The results support the view that objects are important units of saccadic selection. Reconciling the salience view with the object view, we suggest that visual salience contributes to prioritization among objects. Moreover, the data point towards an increasing relevance of object-bound information with increasing age.

Sensory-cognitive associations are only weakly mediated or moderated by social factors in the Canadian Longitudinal Study on Aging

Sensory and cognitive function both tend to decline with increasing age. Sensory impairments are risk factors for age-related cognitive decline and dementia. One hypothesis about sensory-cognitive associations is that sensory loss results in social isolation which, in turn, is a risk factor for cognitive decline. We tested whether social factors are associated with cognitive and sensory function, and whether sensory-cognitive associations are mediated or moderated by social factors. We used cross-sectional data from 30,029 participants in the Canadian Longitudinal Study of Aging, aged 45-85 years, who had no reported cognitive impairment or diagnosis of dementia. We found strong independent associations of self-reported social variables with hearing (pure-tone audiometry), vision (pinhole-corrected visual acuity), and executive function and weaker associations with memory. The moderating and mediating effects of social variables on sensory-cognitive associations were weak and mostly non-significant, but social factors could be slightly more important for females and older people. Partial retirement (relative to full retirement or not being retired) may have protective effects on cognition in the presence of hearing loss. These findings confirm the association between social factors and sensory and cognitive measures. However, support is weak for the hypothesis that social factors shape sensory-cognitive associations.

The Role of Sensory Function in Processing Speed and Working Memory Aging

BACKGROUND

Sensory function, processing speed, and working memory are considered to be mechanisms that play important explanatory roles in age-related decline of cognitive abilities. As individuals age, sensory function declines along with other cognitive abilities, including processing speed and working memory. Moreover, the relationship between sensory function, processing speed, and working memory, which represent the most basic mechanism, is one of the important issues in the field of cognitive aging.

METHODS

To explore the role of sensory function, especially visual function, in processing speed and working memory aging, the present study adopted a 2 (age: young and old) × 4 (visual perceptual stress: high, medium, low, and non-stress) mixed design and explored age differences in tasks testing processing speed and working memory. To generate different levels of visual perceptual stress, test materials were masked with Gaussian noise according to each individual's visual function.

RESULTS

The results indicated that age differences in processing speed were not influenced by different levels of visual perceptual stress, while age differences in working memory performance decreased gradually with the increase of visual perceptual stress.

CONCLUSION

Visual function affected age differences in working memory rather than in processing speed. The common-cause hypothesis and information-degradation hypothesis were applied to interpret the relationships between visual function and processing speed and between visual function and working memory, respectively. Moreover, sensory function may not directly affect working memory function, which was also consistent with a resource decrement model of aging.

Age-related changes in the relationship between visual exploration and hippocampal activity

Deciphering the mechanisms underlying age-related memory declines remains an important goal in cognitive neuroscience. Recently, we observed that visual sampling behavior predicted activity within the hippocampus, a region critical for memory. In younger adults, increases in the number of gaze fixations were associated with increases in hippocampal activity (Liu et al., 2017). This finding suggests a close coupling between the oculomotor and memory system. However, the extent to which this coupling is altered with aging has not been investigated. In this study, we gave older adults the same face processing task used in Liu et al. (2017) and compared their visual exploration behavior and neural activation in the hippocampus and the fusiform face area (FFA) to those of younger adults. Compared to younger adults, older adults showed an increase in visual exploration as indexed by the number of gaze fixations. However, the relationship between visual exploration and neural responses in the hippocampus and FFA was weaker than that of younger adults. Older adults also showed weaker responses to novel faces and a smaller repetition suppression effect in the hippocampus and FFA compared to younger adults. All together, this study provides novel evidence that the capacity to bind visually sampled information, in real-time, into coherent representations along the ventral visual stream and the medial temporal lobe declines with aging.

Older Adults Benefit from Symmetry, but Not Semantic Availability, in Visual Working Memory

Visual working memory exhibits age effects that are amongst the largest observed in the cognitive aging literature. In this research we investigated whether or not older adults can benefit from visual symmetry and semantic availability, as young adults typically do. Visual matrix pattern tasks varied in terms of the perceptual factor of symmetry (Experiment 1), as well as the availability of visual semantics, or long-term memory (LTM; Experiment 2). In Experiment 1, within a visual memory span protocol, four matrix pattern sets were employed with discrete symmetry characteristics; random, vertical, horizontal, and diagonal symmetry. Encoding time was 3 s with a 2 s maintenance interval. The findings indicated a significant difference in span level across age groups for all of the symmetry variants. More importantly, both younger and older adults could take advantage of symmetry in the matrix array in order to significantly improve task performance. In Experiment 2, two visual matrix task sets were used, with visual arrays of either low or high semantic availability (i.e., they contained stimuli with recognizable shapes that allow for LTM support). Encoding duration was 3 s with a 1 s retention interval. Here, the older adult sample was significantly impaired in span performance with both variants of the task. However, only the younger adult participants could take advantage of visual semantics. These findings show that, in the context of overall impairment in individual task performance, older adults remain capable of employing the perceptual cue of symmetry in order to improve visual working memory task performance. However, they appear less able, within this protocol, to recruit visual semantics in order to scaffold performance.

Linking cognitive and visual perceptual decline in healthy aging: The information degradation hypothesis

Several hypotheses attempt to explain the relation between cognitive and perceptual decline in aging (e.g., common-cause, sensory deprivation, cognitive load on perception, information degradation). Unfortunately, the majority of past studies examining this association have used correlational analyses, not allowing for these hypotheses to be tested sufficiently. This correlational issue is especially relevant for the information degradation hypothesis, which states that degraded perceptual signal inputs, resulting from either age-related neurobiological processes (e.g., retinal degeneration) or experimental manipulations (e.g., reduced visual contrast), lead to errors in perceptual processing, which in turn may affect non-perceptual, higher-order cognitive processes. Even though the majority of studies examining the relation between age-related cognitive and perceptual decline have been correlational, we reviewed several studies demonstrating that visual manipulations affect both younger and older adults' cognitive performance, supporting the information degradation hypothesis and contradicting implications of other hypotheses (e.g., common-cause, sensory deprivation, cognitive load on perception). The reviewed evidence indicates the necessity to further examine the information degradation hypothesis in order to identify mechanisms underlying age-related cognitive decline.