Side and type of initial motor symptom influences visuospatial functioning in Parkinson's disease

Side of motor symptom onset predicts sustained attention deficits and motor improvements after attention training in Parkinson's disease

OBJECTIVE

Parkinson's disease (PD) side of motor symptom onset has been associated with distinct cognitive deficits; individuals with left-side onset (LPD) show more visuospatial impairments, whereas those with right-side onset (RPD) show more verbal impairments. Non-spatial attention is a critical cognitive ability associated with motor functioning that is right hemisphere lateralized but has not been characterized with regard to PD side of onset. We compared individuals with LPD and RPD on non-spatial attention tasks and examined differential responses to a 4-week sustained attention training program.

METHOD

Participants included 9 with LPD and 12 with RPD, who performed both brief and extended go/no-go continuous performance tasks and an attentional blink task. Participants also engaged in an at-home sustained attention training program, Tonic and Phasic Alertness Training (TAPAT), 5 days/week for 4 weeks. We assessed cognitive and motor symptoms before and after training, and after a 4-week no-contact period.

RESULTS

At baseline, participants with LPD exhibited worse performance than those with RPD on the extended continuous performance task, indicating specific deficits in sustaining attention. Poorer attention was associated with worse clinical motor scores. Notably, side of onset had a significant effect on clinical motor changes after sustained attention training, with only LPD participants improving after training, and 4/9 showing clinically meaningful improvements.

CONCLUSIONS

Compared to RPD, participants with LPD had poorer sustained attention pre-training and were more likely to improve on clinical motor functioning after sustained attention training. These findings support mechanistic differences between LPD and RPD and suggest potential differential treatment approaches.

Gray and white matter alterations in different predominant side and type of motor symptom in Parkinson's disease

Background

Parkinson's disease (PD) is highly heterogeneous reflected by different affected side of body and type of motor symptom. We aim to explore clinical characteristics and underlying brain structure alterations in PD with different predominant sides and motor types.

Methods

We recruited 161 PD patients and 50 healthy controls (HC). Patients were classified into four subtypes according to their predominant side and motor type: left akinetic/rigid‐dominant (LAR), left tremor‐dominant (LTD), right akinetic/rigid‐dominant (RAR), and right tremor‐dominant (RTD). All participants assessed motor and cognitive performances, then underwent T1‐weighted and diffusion tensor imaging scanning. A general linear model was used to compare neuroimaging parameters among five groups.

Results

Among four PD subtypes, patients of LAR subtype experienced the worst motor impairment, and only this subtype showed worse cognitive performance compared with HC. Compared with HC and other subtypes, LAR subtype showed a significant reduction in cortical thickness of the right caudal‐anterior‐cingulate gyrus and fractional anisotropy of the right cingulum bundle.

Conclusions

We demonstrated that LAR subtype had the worst clinical performance, which the severer damage in the right cingulate region might be the underlying mechanism. This study underscores the importance of classifying PD subtypes based on both the side and type of motor symptom for clinical intervention and research to optimize behavioral outcomes in the future.

Taking the Time to Assess Cognition in Parkinson's Disease: The Clock Drawing Test

BACKGROUND

Cognitive impairment is common and disabling in Parkinson's disease (PD). Cognitive testing can be time consuming in the clinical setting. One rapid test to detect cognitive impairment in non-PD populations is the Clock Drawing Test (CDT), which calls upon the brain's executive and visuospatial abilities to draw a clock designating a certain time.

OBJECTIVE

Test the hypothesis that PD participants would perform worse on CDT compared to controls and that CDT would correlate with other measures of cognition.

METHODS

This study evaluated two independent CDT scoring systems and differences in CDT performance between PD (N = 97) and control (N = 54) participants using a two-sample t-test. Pearson's correlations were conducted between the CDT and tests of sleepiness (Epworth Sleepiness Scale) and vigilance (Psychomotor Vigilance Test); executive function (Trails B-A); and global cognition (Montreal Cognitive Assessment). Receiver operating characteristic curves were used to determine cut points on the CDT that identify individuals who need additional cognitive testing.

RESULTS

PD participants had worse performance on CDT compared to controls. The CDT was correlated with executive function (Trails B-A) and global cognition (Montreal Cognitive Assessment). The CDT correlated with vigilance (Psychomotor Vigilance Task) only in healthy controls. However, the CDT was not correlated with measures of sleepiness (Epworth Sleepiness Scale) in either group. A cut point of 9 on the Rouleau scale and 18 on the Mendez scale identified PD participants with cognitive impairment.

CONCLUSION

The CDT is a rapid clinical cognitive assessment that is feasible in PD and correlates with other measures of cognition.

Dopaminergic Basis of Spatial Deficits in Early Parkinson's Disease

Dopaminergic mechanisms regulating cognitive and motor control were evaluated comparing visuoperceptual and perceptuomotor functions in Parkinson's disease (PD). The performance of PD patients (n = 40) was contrasted with healthy controls (n = 42) across two separate visits (on and off dopaminergic medications) on computerized tasks of perception and aiming to a target at variable stimulus lengths (4, 8, 12 cm). Novel visuoperceptual tasks of length equivalence and width interval estimations without motor demands were compared with tasks estimating spatial deviation in movement termination. The findings support the presence of spatial deficits in early PD, more pronounced with increased discrimination difficulty, and with shorter stimulus lengths of 4 cm for both visuoperceptual and perceptumotor functions. Dopaminergic medication had an adverse impact on visuoperceptual accuracy in particular for length equivalence estimations, in contrast with dopaminergic modulation of perceptuomotor functions that reduced angular displacements toward the target. The differential outcomes for spatial accuracy in perception versus movement termination in PD are consistent with involvement of the direct pathway and models of progressive loss of dopamine through corticostriatal loops. Future research should develop validated and sensitive standardized tests of perception and explore dopaminergic selective deficits in PD to optimize medication titration for motor and cognitive symptoms of the disease.

Subthalamic deep brain stimulation affects heading perception in Parkinson's disease

Parkinson's disease (PD) presents with visuospatial impairment and falls. It is critical to understand how subthalamic deep brain stimulation (STN DBS) modulates visuospatial perception. We hypothesized that DBS has different effects on visual and vestibular perception of linear motion (heading), a critical aspect of visuospatial navigation; and such effects are specific to modulated STN location. Two-alternative forced-choice experiments were performed in 14 PD patients with bilateral STN DBS and 19 age-matched healthy controls (HC) during passive en bloc linear motion and 3D optic-flow in immersive virtual reality measured vestibular and visual heading. Objective measure of perception with Weibull psychometric function revealed that PD has significantly lower accuracy [L: 60.71 (17.86)%, R: 74.82 (17.44)%] and higher thresholds [L: 16.68 (12.83), R: 10.09 (7.35)] during vestibular task in both directions compared to HC (p < 0.05). DBS significantly improved vestibular discrimination accuracy [81.40 (14.36)%] and threshold [4.12 (5.87), p < 0.05] in the rightward direction. There were no DBS effects on the slopes of vestibular psychometric curves. Visual heading perception was better than vestibular and it was comparable to HC. There was no significant effect of DBS on visual heading response accuracy or discrimination threshold (p > 0.05). Patient-specific DBS models revealed an association between change in vestibular heading perception and the modulation of the dorsal STN. In summary, DBS may have different effects on vestibular and visual heading perception in PD. These effects may manifest via dorsal STN putatively by its effects on the cerebellum.

Patients with Parkinson's Disease Show Alteration in their Visuospatial Abilities and in their Egocentric and Allocentric Spatial Orientation Measured by Card Placing Tests

BACKGROUND

Visuospatial skills are impaired in Parkinson's disease (PD). Other related skills exist, such as spatial orientation have been poorly studied. The egocentric (based on internal cues) and allocentric frameworks (based on external cues) are used in daily spatial orientation. Depending on PD onset, the allocentric framework may have a higher level of impairment in tremor-dominant and the egocentric one in akinetic-rigid.

OBJECTIVE

To evaluate spatial orientation and visuospatial functions in PD patients and controls, and to assess whether their performance is related to disease duration and the PD subtype (tremor-dominant and akinetic-rigid).

METHODS

We evaluated egocentric and allocentric spatial orientation (Egocentric and Allocentric Spatial Memory Tasks) and visuospatial abilities, span and working memory in 59 PD patients and 51 healthy controls.

RESULTS

Visuospatial skills, visuospatial span, and egocentric and allocentric orientation are affected in PD. Visuospatial skills and allocentric orientation undergo deterioration during the first 5 years of the disease progression, while egocentric orientation and visuospatial span do so at later stages (9-11 years). The akinetic-rigid subtype presents worse results in all the spatial abilities that were measured when compared to controls, and worse scores in visuospatial working memory, visuospatial abilities and allocentric orientation when compared to the tremor-dominant group. The tremor-dominant group performed worse than controls in egocentric and allocentric orientation.

CONCLUSION

PD patients show deficits in their visuospatial abilities and in their egocentric and allocentric spatial orientation compared to controls, specifically in akinetic-rigid PD. Only spatial orientation are affected in tremor-dominant PD patients. Allocentric orientation is affected earlier in the progression of the disease.

Directional Bias in Line Orientation Test Errors in Parkinson's Disease

OBJECTIVE

Value in evaluating error subtypes on visuospatial line orientation tests has been reported. Directional bias metrics for line orientation test errors represent easily quantifiable data that have not previously been studied. We evaluated whether patients with a clinical condition known to affect visuospatial functioning (Parkinson's disease [PD]) exhibited unique directional error patterns on the RBANS Line Orientation test relative to other neuropsychology-referred patients.

METHOD

We compared overall directional bias in errors, directional bias by line location (left or right line and visual field), and absolute error rates (regardless of direction) by line location in a retrospective sample of patients with PD and a sample of neuropsychology-referred patients without PD. Groups were roughly matched on age, education, gender, and overall level of cognitive impairment.

RESULTS

Patients with PD exhibited higher rates of leftward bias in errors, both overall and for the left stimulus line in each pair. Directional bias error scores better predicted PD versus non-PD group status than RBANS Line Orientation raw scores. Classification accuracy data for these variables were modest in the entire sample but stronger in a subsample of patients with mild levels of overall cognitive impairment.

CONCLUSIONS

Directional bias metrics for line orientation tests represent easily quantifiable data with potential theoretical and clinical value. In our sample, patients with PD made more left-biased line orientation errors than other neuropsychology-referred patients. By themselves, directional bias scores may have limited diagnostic potential, but they may be useful in diagnostic classification models and may have implications for clinical care.

Spatial judgment in Parkinson's disease: Contributions of attentional and executive dysfunction

Spatial judgment is impaired in Parkinson's disease (PD), with previous research suggesting that disruptions in attention and executive function are likely contributors. If judgment of center places demands on frontal systems, performance on tests of attention/executive function may correlate with extent of bias in PD, and attentional disturbance may predict inconsistency in spatial judgment. The relation of spatial judgment to attention/executive function may differ for those with left-side versus right-side motor onset (LPD, RPD), reflecting effects of attentional lateralization. We assessed 42 RPD, 37 LPD, and 67 healthy control participants with a Landmark task (LM) in which a cursor moved horizontally from the right (right-LM) or left (left-LM). The task was to judge the center of the line. Participants also performed neuropsychological tests of attention and executive function. LM group differences were found on left-LM only, with both PD subgroups biased leftward of the control group (RPD p < .05; LPD p < .01; no RPD-LPD difference). For left-LM trials, extent of bias significantly correlated with performance on the cognitive tasks for PD but not for the control group. PD showed greater variability in perceived center than the control group; this variability correlated with performance on the cognitive tasks. The correlations between performance on the test of spatial judgment and the tests of attention/executive function suggest that frontal-based attentional dysfunction affects dynamic spatial judgment, both in extent of spatial bias and in consistency of response as indexed by intertrial variability. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Psychometric properties of clock and pelvic drawings in Parkinson's disease: A validity and cross-sectional study

OBJECTIVES

Parkinson's disease (PD) is characterized by visuospatial and body schema deficits. People with PD often exhibit hypometric movements and graphic hypometria (i.e., small drawing dimensions). The goal of the current study was to explore graphic-metric representation in people with PD by assessing pelvic and clock drawing dimensions (i.e., height and width) and by investigating associations between pelvic drawing dimensions and participant characteristics.

METHODS

Twenty people (16 males, 4 females; M age: 65.75 ± 10.13 years) with idiopathic PD (Hoehn &Yahr Stages I-III) volunteered to participate in this study. Draw Your Pelvis and Clock Drawing tests were used for assessing drawing dimensions, which were then correlated with PD severity, stage and duration, cognitive level, side of symptoms onset, and pelvic schema score. Bivariate and multiple linear regression analyses were also used.

RESULTS

Excellent (.844-.999) interrater reliability was shown for measuring pelvic and clock drawing dimensions. Pelvic drawing dimensions did not significantly (P > .05) differ in magnitude, whereas clock drawing height was significantly (p < .01) greater than width, both suggesting graphic dysmetria (i.e., distorted graphic dimensions). Pelvic drawing width was negatively associated with PD severity and stage, was positively associated with pelvic schema score, and predicted all three parameters.

CONCLUSION

Measuring pelvic drawing dimensions, and specifically pelvic drawing width, holds potential as an adjunct diagnostic measure in PD assessments and for detecting pelvic schema deficits or misperceptions. This test can be used by physical therapists in the clinic for assessing disease severity, stage, and pelvic schema in people with PD. The knowledge gained from this study contributes to a greater understanding of graphic-metric representation and associated deficits in people with PD. Future studies should explore the relationship between pelvic drawing dimensions and pelvic mentally imaged estimates, and their role in motor planning, control, and execution in people with PD.

The Body Position Spatial Task, a Test of Whole-Body Spatial Cognition: Comparison Between Adults With and Without Parkinson Disease

BACKGROUND

The Body Position Spatial Task (BPST) is a novel measure of whole-body spatial cognition involving multidirectional steps and turns. Individuals with Parkinson disease (PD) are affected by motor and cognitive impairments, particularly in spatial function, which is important for mental imagery and navigation. Performance on the BPST may inform understanding of motor-cognitive and spatial cognitive function of individuals with PD.

OBJECTIVES

We conducted this study to determine feasibility and validity of the BPST with standard, validated, and reliable measures of spatial cognition and motor-cognitive integration and to compare BPST performance in adults with and without PD.

METHODS

A total of 91 individuals with mild-moderate PD and 112 neurotypical (NT) adults of similar age were recruited for the study to complete the BPST and other measures of mobility and cognition. Correlations were used to determine construct and concurrent validity of BPST with valid measures of spatial cognition and motor-cognitive integration. Performance was compared between PD and NT adults using independent t-tests.

RESULTS

BPST was feasible to administer. Analyses show evidence of construct validity for spatial cognition and for motor-cognitive integration. Concurrent validity was demonstrated with other tests of mobility and cognition. Relationships were stronger and more significant for individuals with PD than for NT individuals. BPST performance was not significantly different between groups.

CONCLUSION

Tests that integrate cognitive challenge in mobility contexts are necessary to assess the health of spatial cognitive and motor-cognitive integration. The BPST is a feasible and valid test of whole-body spatial cognition and motor-cognitive integration in individuals with PD.

Age and Graphomotor Decision Making Assessed with the Digital Clock Drawing Test: The Framingham Heart Study

BACKGROUND

Digital Clock Drawing Test (dCDT) technology enables the examination of detailed neurocognitive behavior as behavior unfolds in real time; a capability that cannot be obtained using a traditional pen and paper testing format.

OBJECTIVE

Parameters obtained from the dCDT were used to investigate neurocognitive constructs related to higher-order neurocognitive decision making and information processing speed. The current research sought to determine the effect of age as related to combined motor and non-motor components of drawing, and higher-order decision making latencies.

METHODS

A large group of stroke- and dementia- free Framingham Heart Study participants were administered the dCDT to command and copy with hands set for "10 after 11". Six age groups (age range 28-98) were constructed.

RESULTS

Differences between age groups were found for total time to completion, total pen stroke count, and higher-order decision making latencies in both command and copy test conditions.

CONCLUSION

Longer age-related decision making latencies may reflect a greater need for working memory and increased self-monitoring in older subjects. These latency measures have potential to serve as neurocognitive biomarkers of Alzheimer's disease and other insidious neurodegenerative disorders.

Cognitive impairment in Parkinson's disease, Alzheimer's dementia, and vascular dementia: the role of the clock-drawing test

AIM

Cognitive impairment is present in several neurodegenerative disorders. The clock-drawing test (CDT) represents a useful screening instrument for assessing the evolution of cognitive decline. The aim of this study was to investigate the sensitivity of the CDT in monitoring and differentiating the evolution of cognitive decline in Alzheimer's dementia (AD), vascular dementia (VaD), and Parkinson's disease (PD).

METHODS

This study involved 139 patients, including 39 patients with PD and mild cognitive impairment, 16 demented PD patients, 21 VaD patients with mild cognitive impairment, 17 patients with VaD, 33 patients with mild cognitive impairment due to AD, and 13 patients with probable AD. All participants completed the CDT. The Mini-Mental State Examination was administered to establish patients' cognitive functioning.

RESULTS

Comparisons of quantitative and qualitative CDT scores showed significant differences between the various diseases. Impairment of executive functioning seems to be more pronounced in PD and VaD than in AD. Patients with AD committed more errors related to a loss of semantic knowledge, indicating a severely reduced capacity in abstract and conceptual thinking.

CONCLUSION

Results support the usefulness and sensitivity of the CDT in the detection of different dementia subtypes. Qualitative error analysis of the CDT may be helpful in differentiating PD, VaD, and AD, even in the early stages of each disease.

Cognitive and behavioral disorders in Parkinson's disease: an update. I: cognitive impairments

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by motor symptoms such as rigidity, rest tremor, and bradykinesia. However, a growing body of evidence demonstrated that PD encompasses several non-motor disturbances as well, such as cognitive impairment. Cognitive defects can be present since early stages of the disease but tend to dominate the clinical picture as the disease progresses. Around 40% of patients with PD present with cognitive impairments in several cognitive domains including attention, working memory and executive functions, language, visuospatial skills, and episodic memory; in later stages of the disease, cognitive defects and associated behavioral disorders concur to determine clinically relevant PD-associated dementia. Part of these defects is ascribed to a dopamine-dependent dysfunction of fronto-striatal pathways, but there is a considerable heterogeneity in the cognitive impairments as well as a suggestion of the role of other neurotransmitter systems, such as the cholinergic one, mainly responsible for Parkinson-dementia syndrome. In this paper, we review recent literature with particular attention to the last 5 years on the main cognitive deficits described in PD patients as well as on the hypothesized neuro-functional substrate of such impairments. Finally, we provide some suggestions on how to test cognitive functions in PD appropriately.

Does Side of Onset Influence the Pattern of Cerebral Atrophy in Parkinson's Disease?

Background

Imaging studies have revealed widespread neurodegeneration in Parkinson’s disease (PD), but only a few considered the issue of asymmetrical clinical presentations.

Objective

To investigate if the side of onset influences the pattern of gray matter (GM) atrophy in PD.

Methods

Sixty patients (57.87 ± 10.27 years) diagnosed with idiopathic PD according to the U.K. Brain Bank criteria, 26 with right-sided disease onset (RDO) and 34 with left-sided disease onset (LDO), were compared to 80 healthy controls (HC) (57.1 ± 9.47 years). We acquired T1-weighted images on a 3 T scanner. Images were processed and analyzed with VBM8 (SPM8/Dartel) on Matlab R2012b platform. Statistic assessments included a two-sample test (family-wise error p < 0.05) with extent threshold of 20 voxels.

Results

Compared to HC, LDO patients had GM atrophy in the insula, putamen, anterior cingulate, frontotemporal cortex, and right caudate, while the RDO group showed atrophy at the anterior cingulate, insula, frontotemporal, and occipital cortex.

Conclusion

This study revealed widespread GM atrophy in PD, predominantly in the left hemisphere, regardless of the side of onset. Future investigations should also consider handedness and side of onset to better characterize cerebral involvement and its progression in PD.

Gait in Parkinson's disease: A visuo-cognitive challenge

Vision and cognition have both been related to gait impairment in Parkinson's disease (PD) through separate strands of research. The cumulative and interactive effect of both (which we term visuo-cognition) has not been previously investigated and little is known about the influence of cognition on vision with respect to gait. Understanding the role of vision, cognition and visuo-cognition in gait in PD is critical for data interpretation and to infer and test underlying mechanisms. The purpose of this comprehensive narrative review was to examine the interdependent and interactive role of cognition and vision in gait in PD and older adults. Evidence from a broad range of research disciplines was reviewed and summarised. A key finding was that attention appears to play a pivotal role in mediating gait, cognition and vision, and should be considered emphatically in future research in this field.

Abnormal regional homogeneity in Parkinson's disease: a resting state fMRI study

AIM

To examine the functional brain alterations in Parkinson's disease (PD) by measuring blood oxygenation level dependent (BOLD) functional MRI (fMRI) signals at rest while controlling for the structural atrophy.

MATERIALS AND METHODS

Twenty-three PD patients and 20 age, gender, and education level matched normal controls (NC) were included in this study. Resting state fMRI and structural MRI data were acquired. The resting state brain activity was measured by the regional homogeneity (ReHo) method and the grey matter (GM) volume was attained by the voxel-based morphology (VBM) analysis. Two-sample t-test was then performed to detect the group differences with structural atrophy as a covariate.

RESULTS

VBM analysis showed GM volume reductions in the left superior frontal gyrus, left paracentral lobule, and left middle frontal gyrus in PD patients as compared to NC. There were widespread ReHo differences between NC and PD patients. Compared to NC, PD patients showed significant alterations in the motor network, including decreased ReHo in the right primary sensory cortex (S1), while increased ReHo in the left premotor area (PMA) and left dorsolateral prefrontal cortex (DLPFC). In addition, a cluster in the left superior occipital gyrus (SOG) also showed increased ReHo in PD patients.

CONCLUSION

The current findings indicate that significant changes of ReHo in the motor and non-motor cortices have been detected in PD patients, independent of age, gender, education level, and structural atrophy. The present study thus suggests ReHo abnormalities as a potential biomarker for the diagnosis of PD and further provides insights into the biological mechanism of the disease.

Normal discrimination of spatial frequency and contrast across visual hemifields in left-onset Parkinson's disease: evidence against perceptual hemifield biases

Individuals with Parkinson's disease (PD) with symptom onset on the left side of the body (LPD) show a mild type of left-sided visuospatial neglect, whereas those with right-onset (RPD) generally do not. The functional mechanisms underlying these observations are unknown. Two hypotheses are that the representation of left-space in LPD is either compressed or reduced in salience. We tested these hypotheses psychophysically. Participants were 31 non-demented adults with PD (15 LPD, 16 RPD) and 17 normal control adults (NC). The spatial compression hypothesis was tested by showing two sinusoidal gratings, side by side. One grating's spatial frequency (SF) was varied across trials, following a staircase procedure, whereas the comparison grating was held at a constant SF. While fixating on a central target, participants estimated the point at which they perceived the two gratings to be equal in SF. The reduced salience hypothesis was tested in a similar way, but by manipulating the contrast of the test grating rather than its SF. There were no significant differences between groups in the degree of bias across hemifields for SF discrimination or for contrast discrimination. Results did not support either the spatial compression hypothesis or the reduced salience hypothesis. Instead, they suggest that at this perceptual level, LPD do not have a systematically biased way of representing space in the left hemifield that differs from healthy individuals, nor do they perceive stimuli on the left as less salient than stimuli on the right. Neglect-like syndrome in LPD instead presumably arises from dysfunction of higher-order attention.