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Patterns of visual scanning as predictors of emotion identification in normal aging

Emotion identification appears to decline with age, and deficient visual scanning may contribute to this effect. Eye movements of 20 older adults (OAs) and 20 younger adults (YAs) with normal saccades were recorded while viewing facial expressions. OAs made fewer fixations overall, and they made a higher proportion of fixations to the lower halves of faces. Topographical distribution of fixations predicted better OA accuracy for identifying disgust than other negative emotions. Impaired OA accuracy for fear and anger was specific to vision, with normal identification of these emotions in the auditory domain. Age-related frontal-lobe atrophy may affect the integrity of the frontal eye fields, with consequent scanning abnormalities that contribute to difficulties in identifying certain emotions.

Specific impairments in the recognition of emotional facial expressions in Parkinson's disease.

Studies investigating the ability to recognize emotional facial expressions in non-demented individuals with Parkinsons disease (PD) have yielded equivocal findings. A possible reason for this variability may lie in the confounding of emotion recognition with cognitive task requirements, a confound arising from the lack of a control condition using non-emotional stimuli. The present study examined emotional facial expression recognition abilities in 20 non-demented patients with PD and 23 control participants relative to their performance on a non-emotional landscape categorization test with comparable task requirements. We found that PD participants were normal on the control task but exhibited selective impairments in the recognition of facial emotion, specifically for anger (driven by those with right hemisphere pathology) and surprise (driven by those with left hemisphere pathology), even when controlling for depression level. Male but not female PD participants further displayed specific deficits in the recognition of fearful expressions. We suggest that the neural substrates that may subserve these impairments include the ventral striatum, amygdala, and prefrontal cortices. Finally, we observed that in PD participants, deficiencies in facial emotion recognition correlated with higher levels of interpersonal distress, which calls attention to the significant psychosocial impact that facial emotion recognition impairments may have on individuals with PD.

Enhanced stimulus strength improves visual cognition in aging and Alzheimer's disease.

Deficits in visual cognition in Alzheimers disease (AD) arise from neuropathological changes in higher-order association areas of the cortex and from defective input from lower-level visual processing areas. We investigated whether enhanced signal strength may lead to improvement of visual cognition in AD. We tested 35 individuals with probable AD, 35 age-matched elderly control (EC) and 58 young control (YC) adults on letter identification, word reading, picture naming, discrimination of unfamiliar faces, and pattern completion. The contrast sensitivity step-difference across an independent sample of AD and EC groups was used in calculating an image filter, from which we produced stimulus-strength conditions of low-degraded, medium-normal, and high-enhanced. Using this filter we created a hypothetical proximal-strength equivalence between AD at medium strength and EC at low strength, and between AD at high strength and EC at medium strength. For letter identification, word reading, picture naming, and face discrimination, medium strength elicited AD accuracy levels and reaction times that were similar to those of EC at low strength. On picture naming, increased strength reduced perceptual-type errors for EC and AD and random errors for AD. For word reading, high strength elicited AD accuracy levels and reaction times that were equivalent to those of EC at medium strength. We saw no effect of signal-strength manipulation on performance of pattern completion, possibly owing to the complex cognitive demands of that task or to the inadequacy of the filter for its images. The results indicate that putative AD-EC differences in cognition directly reflect contrast sensitivity differences between the groups. Enhancement of stimulus strength can ameliorate vision-based deficits and lead to improvement in some aspects of cognitive performance. These results suggest new non-pharmacological avenues to explore in the attempt to improve cognition in elderly adults and especially in individuals with AD.

Enhanced stimulus contrast normalizes visual processing of rapidly presented letters in Alzheimer's disease.

Deficient perception and cognition in Alzheimers disease (AD) has been attributed to slow information processing and attentional disturbance, but an additional explanation may be reduced signal strength. In 21 individuals with probable AD, 29 healthy older and 54 younger adults, we enhanced the contrast level of rapidly-flashed masked letters. The AD group reached identification criterion (80% accuracy), but required significantly higher contrast than the control groups. A source of the prevalent masking deficit may be reduced signal strength arising from dysfunction of retina or visual cortex. Increasing stimulus contrast may be an effective means of enhancing cognitive performance in AD.

Effects of orthostatic hypotension on cognition in Parkinson disease

Objective: To investigate the relation between orthostatic hypotension (OH) and posture-mediated cognitive impairment in Parkinson disease (PD) using a cross-sectional and within-group design. Methods: Individuals without dementia with idiopathic PD included 18 with OH (PDOH) and 19 without OH; 18 control participants were also included. Neuropsychological tests were conducted in supine and upright-tilted positions. Blood pressure was assessed in each posture. Results: The PD groups performed similarly while supine, demonstrating executive dysfunction in sustained attention and response inhibition, and reduced semantic fluency and verbal memory (encoding and retention). Upright posture exacerbated and broadened these deficits in the PDOH group to include phonemic fluency, psychomotor speed, and auditory working memory. When group-specific supine scores were used as baseline anchors, both PD groups showed cognitive changes following tilt, with the PDOH group exhibiting a wider range of deficits in executive function and memory as well as significant changes in visuospatial function. Conclusions: Cognitive deficits in PD have been widely reported with assessments performed in the supine position, as seen in both our PD groups. Here we demonstrated that those with PDOH had transient, posture-mediated changes in excess of those found in PD without OH. These observed changes suggest an acute, reversible effect. Understanding the effects of OH due to autonomic failure on cognition is desirable, particularly as neuroimaging and clinical assessments collect data only in the supine or seated positions. Identification of a distinct neuropsychological profile in PD with OH has quality of life implications, and OH presents itself as a possible target for intervention in cognitive disturbance.

Relation of Parkinson's Disease Subtypes to Visual Activities of Daily Living

Visual perceptual problems are common in Parkinsons disease (PD) and often affect activities of daily living (ADLs). PD patients with non-tremor symptoms at disease onset (i.e., rigidity, bradykinesia, gait disturbance or postural instability) have more diffuse neurobiological abnormalities and report worse non-motor symptoms and functional changes than patients whose initial symptom is tremor, but the relation of motor symptom subtype to perceptual deficits remains unstudied. We assessed visual ADLs with the Visual Activities Questionnaire in 25 non-demented patients with PD, 13 with tremor as the initial symptom and 12 with an initial symptom other than tremor, as well as in 23 healthy control participants (NC). As expected, the non-tremor patients, but not the tremor patients, reported more impairment in visual ADLs than the NC group, including in light/dark adaptation, acuity/spatial vision, depth perception, peripheral vision and visual processing speed. Non-tremor patients were significantly worse than tremor patients overall and on light/dark adaptation and depth perception. Environmental enhancements especially targeted to patients with the non-tremor PD subtype may help to ameliorate their functional disability.

The neuropsychologic deficits of MELAS: Evidence of global impairment

ObjectiveTo examine the neuropsychologic profile of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes) and relate it to neuropathologic findings. BackgroundMELAS is one of over 40 mitochondrial disorders. Symptoms include seizures, strokelike episodes, headaches, memory impairment, hemianopsia, hearing loss, short stature, diffuse limb weakness, exercise intolerance, nausea, and vomiting. Age of onset ranges from 2 to 40 years. A hallmark of MELAS is normal development until the first symptoms appear. MethodBecause information regarding the neuropsychologic functioning of these individuals is sparse, we report findings from detailed neuropsychologic evaluations for a 13-year-old white male and a 33-year-old African-American male with MELAS. ResultsResults revealed global patterns of deterioration in executive function, attention, language, memory, visuospatial, and motor functioning. In both patients, brain scans revealed posterior pathology in the absence of frontal pathology. ConclusionsWe compared our findings with other documented cases and concluded that MELAS is characterized by a pattern of global deterioration. This pattern differs from that observed in other mitochondrial disorders. The absence of identifiable frontal lobe pathology despite the presence of deficits in executive functioning may be related to the distribution patterns of deficient mitochondria and neuronal projection patterns.

Side and Type of Initial Motor Symptom Influences Visuospatial Functioning in Parkinson's Disease

BACKGROUND/OBJECTIVES Visuospatial problems are common in Parkinsons disease (PD) and likely stem from dysfunction in dopaminergic pathways and consequent disruption of cortical functioning. Characterizing the motor symptoms at disease onset provides a method of observing how dysfunction in these pathways influences visuospatial cognition. We examined two types of motor characteristics: Body side (left or right) and type of initial symptom (tremor or symptom other than tremor). METHODS 31 non-demented patients with PD, 16 with left-side onset (LPD) and 15 with right-side onset (RPD), as well as 17 healthy control participants (HC). The PD group was also divided by type of initial motor symptom, 15 having tremor as the initial symptom and 16 having an initial symptom other than tremor. Visuospatial function was assessed with the Clock Drawing Test. RESULTS Of the four Clock Drawing scoring methods used, the Rouleau method showed sensitivity to subgroup differences. As predicted, the LPD and non-tremor subgroups, but not the other subgroups, performed more poorly than the HC group. CONCLUSION The findings provide further evidence for differences in cognition between these subtypes of PD and highlight the importance of considering disease subtypes when examining cognition.

Effect of Visual Cues on the Resolution of Perceptual Ambiguity in Parkinson's Disease and Normal Aging

Parkinsons disease (PD) and normal aging have been associated with changes in visual perception, including reliance on external cues to guide behavior. This raises the question of the extent to which these groups use visual cues when disambiguating information. Twenty-seven individuals with PD, 23 normal control adults (NC), and 20 younger adults (YA) were presented a Necker cube in which one face was highlighted by thickening the lines defining the face. The hypothesis was that the visual cues would help PD and NC to exert better control over bistable perception. There were three conditions, including passive viewing and two volitional-control conditions (hold one percept in front; and switch: speed up the alternation between the two). In the Hold condition, the cue was either consistent or inconsistent with task instructions. Mean dominance durations (time spent on each percept) under passive viewing were comparable in PD and NC, and shorter in YA. PD and YA increased dominance durations in the Hold cue-consistent condition relative to NC, meaning that appropriate cues helped PD but not NC hold one perceptual interpretation. By contrast, in the Switch condition, NC and YA decreased dominance durations relative to PD, meaning that the use of cues helped NC but not PD in expediting the switch between percepts. Provision of low-level cues has effects on volitional control in PD that are different from in normal aging, and only under task-specific conditions does the use of such cues facilitate the resolution of perceptual ambiguity.

Dual tasking in Parkinson's disease: cognitive consequences while walking

Objective: Cognitive deficits are common in Parkinson’s disease (PD) and exacerbate the functional limitations imposed by PD’s hallmark motor symptoms, including impairments in walking. Though much research has addressed the effect of dual cognitive-locomotor tasks on walking, less is known about their effect on cognition. The purpose of this study was to investigate the relation between gait and executive function, with the hypothesis that dual tasking would exacerbate cognitive vulnerabilities in PD as well as being associated with gait disturbances. Method: Nineteen individuals with mild–moderate PD without dementia and 13 age- and education-matched normal control adults (NC) participated. Executive function (set-shifting) and walking were assessed singly and during dual tasking. Results: Dual tasking had a significant effect on cognition (reduced set-shifting) and on walking (speed, stride length) for both PD and NC, and also on stride frequency for PD only. The impact of dual tasking on walking speed and stride frequency was significantly greater for PD than NC. Though the group by condition interaction was not significant, PD had fewer set-shifts than NC on dual task. Further, relative to NC, PD showed significantly greater variability in cognitive performance under dual tasking, whereas variability in motor performance remained unaffected by dual tasking. Conclusions: Dual tasking had a significantly greater effect in PD than in NC on cognition as well as on walking. The results suggest that assessment and treatment of PD should consider the cognitive as well as the gait components of PD-related deficits under dual-task conditions.