Cognitive differences between patients with left-sided and right-sided Parkinson's disease. A review.

At disease onset, patients with Parkinson's disease (PD) typically report one side of the body to be more affected than the other. Previous studies have reported that this motor symptom asymmetry is associated with asymmetric dopaminergic degeneration in the brain. Research on the cognitive repercussions of this asymmetric degeneration has yielded inconsistent results. Here, we review studies that reported on the cognitive performance of patients with left-sided (LPD) or right-sided (RPD) motor symptom predominance. We present evidence that patients with RPD typically experience problems with language-related tasks and verbal memory, whereas patients with LPD more often perform worse on tasks of spatial attention, visuospatial orienting and memory and mental imagery. In general, no differences were found between both groups on tasks measuring attention and executive function. The association between motor asymmetry and cognitive performance indicates that PD does not lead to one typical cognitive profile. The effect of symptom laterality on the cognitive complaints should be considered in the assessment and treatment of each individual patient.

Horizontal and vertical attentional orienting in Parkinson's disease.

Patients with Parkinson's disease (PD) typically suffer from an asymmetric degeneration of dopaminergic cells in the substantia nigra, resulting in right-sided (RPD) or left-sided (LPD) predominance of motor symptomatology. As the dopaminergic system is also involved in attention, we examined horizontal and vertical orienting of attention in LPD (N=10), RPD (N=9) and controls (N=10). Four LPD patients demonstrated left neglect and three LPD patients demonstrated neglect for the upper visual field. LPD patients demonstrated a slower performance in detecting targets in the left hemifield and did not demonstrate a validity effect, unlike RPD patients and controls. RPD patients performed similar to controls, with the exception of one patient showing left and another showing right neglect, and two RPD patients demonstrated lower neglect. In sum, horizontal and vertical orienting of attention can be affected in Parkinson's disease - particularly in LPD - from very subtle slowing to clinically detectable horizontal and/or vertical neglect.

A selective deficit in the appreciation and recognition of brightness: brightness agnosia?

We report a patient with extensive brain damage in the right hemisphere who demonstrated a severe impairment in the appreciation of brightness. Acuity, contrast sensitivity as well as luminance discrimination were normal, suggesting her brightness impairment is not a mere consequence of low-level sensory impairments. The patient was not able to indicate the darker or the lighter of two grey squares, even though she was able to see that they differed. In addition, she could not indicate whether the lights in a room were switched on or off, nor was she able to differentiate between normal greyscale images and inverted greyscale images. As the patient recognised objects, colours, and shapes correctly, the impairment is specific for brightness. As low-level, sensory processing is normal, this specific deficit in the recognition and appreciation of brightness appears to be of a higher, cognitive level, the level of semantic knowledge. This appears to be the first report of 'brightness agnosia'.

The Brixton Spatial Anticipation Test as a test for executive function: validity in patient groups and norms for older adults.

Impairments in executive functioning frequently occur after acquired brain damage, in psychiatric disorders, and in relation to aging. The Brixton Spatial Anticipation Test is a relatively new measure for assessing the ability to detect and follow a rule, an important aspect of executive functioning. To date, normative data on this task are limited, particularly concerning the elderly. This study presents age- and education-adjusted regression-based norms obtained in a group of healthy older participants (n = 283; mean age 67.4 +/- 8.5 years). The applicability and validity of these norms were further examined in different groups of patients with stroke (n = 106), diabetes mellitus (n = 376), MCI/early dementia (n = 70), psychiatric disorders (n = 63), and Korsakoff's syndrome (n = 41). The results showed that patients with Korsakoff's syndrome, stroke, and psychiatric disorders performed significantly worse than healthy controls. Test-retest correlation (n = 83), learning effects, and correlations with other neuropsychological tests were also explored. Based on the present study, the Brixton test appears a useful addition to existing measures of executive functioning. Moreover, the test can be reliably applied in different groups of clinical patients.

Prism adaptation improves voluntary but not automatic orienting in neglect.

Prism adaptation has been shown to temporarily ameliorate the symptoms of unilateral neglect. The underlying mechanisms of change are not yet fully understood. In this study, we investigate the influence of this treatment on attentional orienting under conditions of exogenous (peripheral onset) and endogenous (central symbolic) cueing. In one patient with left visual extinction and recovered neglect, and another patient with left visual neglect, visuo-motor adaptation to a rightward prismatic shift of 10 degrees improved leftward orienting of attention following an endogenous but not an exogenous cue; leftward re-orienting of attention was also improved in the endogenous task for the second patient. We suggest that prism adaptation may ameliorate neglect by improving compensatory processes of leftward voluntary orienting, rather than by a fundamental change in attentional bias.

Prism adaptation moves neglect-related perseveration to contralesional space.

BACKGROUND: Hemi-neglect is a disorder characterized by a disregard of contralesional stimuli. Some neglect patients also show an "exaggerated attention" for the ipsilesional field, reflected in perseverative responses, such as repetitive fixations in the ipsilesional field, ipsilesional revisitings on standard cancellation, or exaggerations in drawings on the ipsilesional side. OBJECTIVE AND METHOD: It is still unclear whether neglect and perseveration are due to a single underlying mechanism. In the present study, we will examine the effect of 4-day-in-a-row prism adaptation on neglect and perseveration severity in a patient with severe perseverations. Additionally, we will examine whether the position of omissions and perseverations on the Star Cancellation will change during the intervention. RESULTS: Our patient showed a decrease in neglect severity and an increase in perseveration severity, suggesting that perseveration and neglect are dissociated phenomena. Interestingly, 4-day-in-a-row prism adaptation gradually moved the predominant position of perseverative responses from right to left as neglect decreased with treatment. CONCLUSIONS: Perseverative responses do not necessarily occur in the ipsilesional sector of space as is generally assumed. Instead, the position of the revisits may be determined by the severity of the neglect, and may shift when the focus of attention moves more contralesionally with recovery.

Confabulation behavior and false memories in Korsakoff's syndrome: role of source memory and executive functioning.

AIMS: Confabulation behavior is common in patients with Korsakoff's syndrome. A distinction can be made between spontaneous and provoked confabulations, which may have different underlying cognitive mechanisms. Provoked confabulations may be related to intrusions on memory tests, whereas spontaneous confabulations may be due to executive dysfunction or a source memory deficit. METHODS: In 19 chronic Korsakoff patients, spontaneous confabulations were quantified by third-party rating (Likert scale). Provoked confabulations were assessed using the Dalla Barba Confabulation Battery. Furthermore, assessment of executive function was performed using an extensive neuropsychological battery. False memories (i.e. intrusions) and source memory were measured using twoparallelversions of a word-list learning paradigm (a modification of the Rey Auditory Verbal Learning Test). RESULTS: There were deficits in source memory, in which patients incorrectly assigned previously learned words to an incorrect word list. Also, Korsakoff patients had extensive executive deficits, but no relationship between the severity of these deficits and the severity of confabulation or intrusions on a memory task was found. CONCLUSION: The present findings provide evidence for a dissociation between spontaneous confabulation, provoked confabulation and false memories.

The modified Location Learning Test: norms for the assessment of spatial memory function in neuropsychological patients.

This study examines the applicability of the modified Location Learning Test (mLLT) as a test of spatial memory in neuropsychological patients. Three groups of participants were examined: stroke patients, patients with diabetes mellitus and healthy participants (N=411). Three error measures were computed, the Total Score (index of overall performance), the Learning Index (the learning curve over subsequent trials) and the Delayed Recall Score, measuring decay over time. The Learning Index was the most sensitive measure, showing differences between the three groups as well as lateralization effects within the stroke group. Also, the mLLT correlated significantly with the Rey Auditory Verbal Learning Test, as well as with age and education level. Regression-based normative data were computed based on the healthy participants. In all, the mLLT appears to be a sensitive and valid test for the detection of object-location memory impairments in clinical groups.

Exploration of the Raven APM-National Adult Reading Test discrepancy as a measure of intellectual decline in older persons.

Previous studies have shown that the discrepancy between performance on "fluid" and "crystallized" intelligence measures may serve as an indicator for intellectual decline. The validity of this procedure in older persons is unknown. The present study developed a multiple regression equation, to predict the Raven Advanced Progressive Matrices (APM) score from the National Adult Reading Test (NART) score and demographic variables in a large sample of healthy older persons (n = 270). The discrepancy between the predicted and observed Raven APM scores was transformed into a percentile distribution as an indicator of intellectual decline, which can be used in clinical practice. The validity of the procedure was further examined by comparing the proportion of persons with a significant decline (at the -1 and -1.65 SD level) between two older patient samples (87 patients with cerebral stroke and 387 patients with diabetes mellitus) by means of χ(2) tests. There was a significantly higher rate of intellectual decline at the -1 SD ("below average") and -1.65 SD ("impaired") cutoff levels for patients with stroke compared with patients with diabetes (stroke, 34% and 14%; diabetes, 16% and 5%, p < .05). These findings suggest that the Raven APM-NART discrepancy may be a useful measure of intellectual decline in older persons.

Repetitive long-term prism adaptation permanently improves the detection of contralesional visual stimuli in a patient with chronic neglect.

The aim of the current study was to investigate long-term effects in spatial awareness after daily exposure to prism adaptation during three months in a patient with hemispatial neglect. Results showed improvement in the detection of stimuli in the contralesional visual field, as measured with perimetry, in the contralesional visual field up to 24 months after ending prism adaptation. These perimetrical results suggest that compensatory eye movements are an unlikely candidate for an underlying mechanism.

Delirium in acute stroke: a predictor of subsequent cognitive impairment? A two-year follow-up study.

OBJECTIVE: Delirium is an independent risk factor for cognitive impairment and development of dementia in medical patients. It has never been thoroughly studied whether this association is also present in the stroke population. Our aim was to evaluate the effects of delirium in the acute phase after stroke on cognitive functioning two years later. METHODS: Two years after stroke, 50 patients (22 with and 28 without delirium in the acute phase) were assessed on two screening instruments for dementia and a neuropsychological test battery. RESULTS: Delirium was an independent predictor for development of dementia as assessed by the Clinical Dementia Rating Scale (odds ratio (OR) 4.7; 95% confidence interval (CI) 1.08 to 20.42) and by the Rotterdam-CAMCOG (OR 7.2, 95% CI 1.88 to 27.89). Cognitive domains most affected in patients with previous delirium were memory, language, visual construction and executive functioning. CONCLUSIONS: Delirium in the acute phase after stroke is an independent predictor for severe cognitive impairment two years after stroke. These findings emphasize the importance of both rapid detection and treatment of delirium after stroke. Furthermore, periodic monitoring and evaluation of cognitive functioning in these vulnerable patients in the years after stroke is strongly recommended.

Repetitive exploration towards locations that no longer carry a target in patients with neglect.

About 50% of neglect patients show ipsilesional target re-exploration on neglect tasks and in daily life. The present study examines whether omissions and revisitings are due to disengagement failure from visible stimuli on the ipsilesional side. Thirteen patients with neglect and nine healthy controls were tested with three versions of the Bells test on touch screen, i.e. a standard cancellation in which targets have to be marked, an erase cancellation in which targets have to be erased, and a condition in which all items (including distracters) have to be erased. Whereas omissions decreased in the full-erase condition, revisitings were the most prominent in this condition. Our study shows that neglect patients also return to previously visited locations which no longer carry a target.

The perception of emotional facial expressions in stroke patients with and without depression.

BACKGROUND: Emotion perception may be impaired after stroke. No study on emotion perception after stroke has taken the influence of post-stroke depressive symptoms into account, although depressive symptoms themselves may hamper emotion perception. OBJECTIVE: To compare the perception of emotional facial expressions in stroke patients with and without depressive symptoms. METHODS: Twenty-two stroke patients participated whose depressive symptoms were classified using the Montgomery-Åsberg Depression Rating Scale (cutoff = 10) and who were compared with healthy controls. Emotion recognition was measured using morphed images of facial expressions. RESULTS: Patients with depressive symptoms performed worse than controls on all emotions; patients without depressive symptoms performed at control level. Patients with depressive symptoms were less sensitive to the emotions anger, happiness and sadness compared with patients without depressive symptoms. CONCLUSIONS: Post-stroke depressive symptoms impair emotion perception. This extends findings in bipolar disorder indicating that emotion perception deficits are strongly related to the level of depression.

The role of executive functioning in spontaneous confabulation.

OBJECTIVE: To follow the recovery course of a patient who exhibited an amnesic-confabulatory syndrome in conjunction with severe executive dysfunction in the first week following bithalamic infarction. BACKGROUND: Previous studies have shown that spontaneous confabulation originates from the combination of amnesia and executive dysfunction and that the degree of confabulation is determined by the degree of executive dysfunction. However, a few studies have also reported a dissociation between spontaneous confabulation and executive dysfunction. Therefore, the role of executive functioning in spontaneous confabulation is presently unclear. METHOD: Clinical examinations, magnetic resonance imaging (MRI), and cognitive and behavioral assessments with a focus on executive functions were conducted within the first week poststroke and after 6 months. RESULTS: MRI showed a bithalamic infarction involving the territory of the paramedian arteries predominantly affecting the dorsomedial and intralaminar nuclei of the thalami. Disappearance of spontaneous confabulation paralleled a specific recovery in mental flexibility, whereas all other executive components and long-term memory remained severely impaired at 6 months poststroke. CONCLUSIONS: Our case study provides additional evidence that mental flexibility, but not executive functioning in general, is a prerequisite for spontaneous confabulation. Direct or indirect functional deactivation of dorsolateral prefrontal cortex may be necessary for the development of spontaneous confabulation.