Contribution of perceptual motor dysfunction to construction and tracing disturbances in Parkinson's disease

Sensorimotor adaptation of voice fundamental frequency in Parkinson's disease

OBJECTIVE

This study examined adaptive responses to auditory perturbation of fundamental frequency (fo) in speakers with Parkinson's disease (PD) and control speakers.

METHOD

Sixteen speakers with PD and nineteen control speakers produced sustained vowels while they received perturbed auditory feedback (i.e., fo shifted upward or downward). Speakers' pitch acuity was quantified using a just-noticeable-difference (JND) paradigm. Twelve listeners provided estimates of the speech intelligibility for speakers with PD.

RESULTS

Fifteen responses from each speaker group for each shift direction were included in analyses. While control speakers generally showed consistent adaptive responses opposing the perturbation, speakers with PD showed no compensation on average, with individual PD speakers showing highly variable responses. In the PD group, the degree of compensation was not significantly correlated with age, disease progression, pitch acuity, or intelligibility.

CONCLUSIONS

These findings indicate reduced adaptation to sustained fo perturbation and higher variability in PD compared to control participants. No significant differences were seen in pitch acuity between groups, suggesting that the fo adaptation deficit in PD is not the result of purely perceptual mechanisms.

SIGNIFICANCE

These results suggest there is an impairment in vocal motor control in PD. Building on these results, contributions can be made to developing targeted voice treatments for PD.

Effect of duration of pitch-shifted feedback on vocal responses in patients with Parkinson's disease

Study of the pitch-shift reflex is useful for the investigation of how auditory feedback is used in the control of voice fundamental frequency. The present study was an attempt to learn if the basal ganglia are involved in central mechanisms of the pitch-shift reflex by comparing measures of the reflex in a group of Parkinson's disease patients with those measures in a group of control participants. The effect of varying duration of the pitch-shift stimulus (PSS) on the voice fundamental frequency (F0) response in 10 Parkinson's disease (PD) patients and 10 age-matched unaffected participants was investigated. Participants were instructed to vocalize into a microphone while their voice was fed back to them over headphones. This feedback of the vocal signal was shifed in pitch either up or down, with the duration of this shift systematically manipulated at 100 ms, 500 ms, and 1000 ms. Although the participants were on medication, making interpretation of the results problematic with regard to basal ganglia function, it was reasoned that positive effects could nevertheless suggest basal ganglia involvement in this reflex and motivate further research. Results indicated that both groups responded to increased stimulus duration of the pitch-shift stimulus with increases in reflex peak time, magnitude, and end times. However, PD patients had significantly longer peak times and end times than control participants for stimulus durations of 100 ms. These results suggest that basal ganglia dysfunction may affect mechanisms relating to the execution and termination of the pitch-shift reflex for brief stimulus durations. The results also support hypotheses of impaired sensory integration of auditory feedback in PD patients.

Cognitive processes involved in delayed non-matching-to-sample performance in Parkinson's disease

Visual recognition memory was assessed in terms of delay duration, memory load and amount of interference(s) in non-demented patients with Parkinson's disease (PD) using an automated delayed non-matching-to-sample (DNMS) task with trial-unique stimuli. Special attention was focused on the different cognitive functions engaged by these patients in solving this recognition memory task. Thirteen patients with PD, carefully selected according to their stable regimen and anticholinergic medication, were compared to 12 controls matched by age and educational level. Besides the DNMS task, a neuropsychological battery that included tasks carefully selected according to processes potentially required to perform the DNMS task (e.g. attention, executive functions, visual discrimination and motor speed) was administered to the subjects. As compared with controls, patients with PD showed a deficit on most DNMS subscores, except those requiring the least cognitive load. The correlative analysis between the DNMS and other neuropsychological tasks suggests involvement of long-term memory mainly in the DNMS performance for the control group, contrasting with a major involvement of executive functions for the patients with PD. These data indicate that visual recognition memory impairment in non-demented patients with PD is largely due to an executive dysfunction, notably in working memory. Several hypotheses are proposed concerning the neuronal substrates underlying the impairment on the visual DNMS task in PD.

The effect of long-term levodopa therapy on depression level in de novo patients with Parkinson's disease

20) became non-depressed, while five patients (22%) among 23 initially non-depressed became depressed. With long-term levodopa therapy, the UPDRS-motor score significantly improved (35+/-15. 7-18+/-7.6), but the BDI score was unchanged (18+/-9.3-19+/-9.2). The initial BDI score was significantly and inversely correlated to the parkinsonian motor symptoms, but their percentage changes were not correlated to each other. These results provide strong support to previous observations that levodopa therapy does not alter parkinsonian depression as well as providing additional evidence to support the role of non-dopaminergic mechanisms in parkinsonian depression.

Delayed motor response correlates with striatal degeneration in Parkinson's disease

OBJECTIVE

Studies on reaction time have suggested a selective deficit of slowness in motor readiness and motor programming in Parkinson's disease (PD). Objective of this study was the putative relation between delayed initiation and execution of movement and the striatal dopamine deficiency in PD.

MATERIAL AND METHODS

We investigated 32 idiopathic, previously untreated parkinsonian patients to evaluate dopaminergic nigrostriatal degeneration by single photon emission tomography in combination with the radiotracer [123I]-beta-CIT and performed a simple reaction time paradigm on the same day.

RESULTS

Significant relations between the [123I]-beta-CIT-SPECT-ratio striatum/cerebellum and reaction--and movement time appeared. Reaction time and movement time of parkinsonian patients were significantly longer compared to age-matched controls.

CONCLUSIONS

We conclude that reaction- and movement-time is related to the dopaminergic nigrostriatal degeneration in untreated parkinsonian subjects.

Performance of sequential arm movements with and without advance knowledge of motor pathways in Parkinson's disease

Patients with Parkinson's disease are slower than normal subjects in executing sequential arm movements, and their bradykinesia worsens as the execution of motor sequences progresses. In parkinsonian and normal subjects, we studied the execution of two types of fast sequential arm movements. The subjects had to perform a motor sequence following with their arm a path marked by six targets on a screen. In one experimental condition, they performed the motor sequence without advance knowledge of its path and executed each submovement in response to the consecutive appearance of the targets on the screen (unknown motor sequences). In the other condition, all the targets appeared simultaneously on the screen before the subject moved, and the subject internally determined when to execute each submovement (known motor sequences). Patients were slower than normal subjects in executing both sequences. Patients and normal subjects were faster in executing known than unknown sequences, but the patients' percentage of total movement time diminished less. During the unknown condition, both groups tended to lengthen submovement duration whereas, during the known condition, both groups tended to correct this trend. Patients performed submovements during both sequences with longer acceleration phases. The submovement symmetry ratio of the velocity profile changed according to the direction of movement (up or down). We conclude that these findings depend mainly on the model of movement execution. They also suggest that patients with Parkinson's disease have more difficulty in executing internally determined than externally triggered sequential movements.

Distorted visual feedback effects on drawing in Parkinson's disease

We investigated the effects of distorted visual feedback on the drawing performance of a group with Parkinson's disease (PD) and a control group. Twenty older healthy adults and 20 PD patients copied figures onto a digitizer tablet with a pen under normal and distorted visual feedback conditions. PD patients were less able than controls to adjust the size of their drawing to compensate for distortions in visual feedback. The effect was particularly pronounced when patients were required to draw smaller than normal. Nevertheless, with practice. PD patients showed a similar degree of improvement in size as controls, although they did not match the control group's level of performance. Overall, these findings support the notion that PD may have specific difficulty adjusting to a change in gain (or discrepancy) between visual and kinesthetic feedback when they must alter the size of their drawing. These findings point to the putative role of the basal ganglia in adjusting for the intermodal discrepancy between sensory feedback, and re-scaling the size of movements.

A technique for removal of the visuoperceptual component from tracking performance and its application to Parkinson's disease

Although it is well established that subjects with Parkinson's disease perform poorly on complex sensory-motor tasks, the extent to which this is due to visuoperceptual deficits is unclear. We measured the performance of 16 patients with Parkinson's disease, both on and off drugs, and 16 age and sex matched control subjects on preview and nonpreview tracking tasks and a nonmotor test of dynamic visuoperception. Order effects were controlled for by a randomized cross-over design. Performance on the perceptual task was measured in terms of perceptual resolution and was found impaired in the Parkinsonian group. The contribution of visuoperceptual function to tracking performance was removed using the concept of a visuoperceptual buffer-zone. The mean tracking error remained impaired on all tracking tasks and demonstrated that limitations is visuoperceptual function play only a minor role in the tracking errors in both Parkinsonian and control subjects. It is clear that the technique for determining the visuoperceptual component of performance on complex sensory-motor tasks has considerable scope for application in studies of a variety of brain disorders.

Perceptual abnormalities in Parkinson's disease: top-down or bottom-up processes?

A wide variety of perceptual impairments have been reported in patients with Parkinson's disease (PD) in recent years; the underlying causes of these impairments have been variously attributed to different levels of the visual-cognitive system, from the retina to frontal cortex. Parkinsonian perceptual abnormalities could thus be interpreted as indirectly caused either by 'bottom-up' effects, stemming from dopaminergic dysfunction in the retina, or by 'top-down' effects, stemming from deficits in attention due to disturbances in the striatal-frontal system. Alternatively, a direct visuospatial impairment, perhaps related to the motor symptoms, has been considered. Data on three basic aspects of visual perception (3-D stereo vision, figure-ground discrimination, and pattern perception) which might be expected to give difficulty to PD subjects suffering changes in early processing mechanisms are reported. Visual complexity and the degree of mental manipulation of the material required both varied in different parts of the tests. PD patients were on stable drug regimens. It was found that disease severity interacted with performance: patients with mild PD showed little perceptual abnormality, patients with moderate PD showed only top-down effects, and patients with severe PD showed evidence both of top-down and of bottom-up deficits. Thus it appears that any retinal effects on perception in PD occur only in the advanced stages of the disease; in earlier stages any visual dysfunction probably reflects top-down disturbances from higher levels of the cognitive-behavioural system.

Improvement of body image perception in Parkinson's disease by treatment with weak electromagnetic fields

Neuropsychological studies have demonstrated that Parkinson's disease (PD) is associated with various cognitive deficits ultimately leading in about 30% of patients to the development of dementia. These studies have demonstrated also a greater decrement of right hemispheric functions which are manifested by visuospatial deficits occurring in up to 90% of PD patients. The Human Figure Drawing Test has been employed in the assessment of generalized intellectual deterioration and specifically in the evaluation of visuperceptive, visuospatial and visuoconstructional abilities in brain injured patients. I have demonstrated recently, on the basis of various drawing tests, that external application of electromagnetic fields (EMFs) in the picotesla (pT) range intensity improved visuoperceptive and visuospatial functions in Parkinsonian patients. In the present communication I present 4 fully medicated nondemented Parkinsonian patients who were administered the Human Figure Drawing Test before and after a series of treatments with EMFs. The Human Figure Drawing Test was selected for the study specifically since it was shown to be sensitive to the effects of surgery to the basal ganglia in Parkinsonian patients. Prior to application of EMFs these patients' drawings showed distortion, poor perspective, impoverished facial expression, and lack of attention to details suggested poor body image perception related to right posterior hemispheric dysfunction. In response to the administration of EMFs the group demonstrated a striking improvement in the drawings particularly the depiction of the face the perception of which is localized to the right parietal lobe. These findings demonstrate that treatment with pT EMFs improves body image perception in Parkinsonian patients, a deficit which may remain unaffected by treatment with standard dopaminergic pharmacotherapy.

Reversal of visuospatial deficit on the Clock Drawing Test in Parkinson's disease by treatment with weak electromagnetic fields

Visuospatial deficits are among the most frequently encountered abnormalities in neuropsychological testing of patients with Parkinson's disease, being present in up to 90% of cases. Clinically, impairment of visuospatial functions may not be noted by Parkinsonian patients but may contribute to various functional disabilities including frequent falls, difficulties operating a vehicle, ambulating, and dressing. I have reported recently that treatment with external electromagnetic fields (EMFs) in the picotesla (pT) range intensity is an effective nonpharmacological modality in the management of the motor and various cognitive deficits of Parkinsonism including visuoperceptive and visuospatial functions. The present communication concerns four fully medicated Parkinsonian patients who, in response to treatment with EMFs, exhibited reversal of visuospatial impairments as demonstrated on the Clock Drawing Test. Specifically, prior to treatment with EMFs these patients demonstrated a visuospatial deficit which was evident by the placement of the numbers on the clock distant from the periphery. Following a series of treatments with EMFs this visuospatial deficit was corrected. The report supports prior observations demonstrating that externally applied pT range intensity EMFs may bring about reversal of visuospatial deficits in Parkinsonian patients which usually are not improved by treatment with dopaminergic or anticholinergic drugs.

The effects of picoTesla range magnetic fields on perceptual organization and visual memory in parkinsonism

Drawing tasks, both free and copied, have achieved a central position in the neuropsychological evaluation of constructional abilities in brain injured patients. The Rey-Osterrieth Complex Figure Test was devised in early 1940s as a tool to investigate perceptual organization and visual memory. The Bicycle Drawing Test is used as a measure of mechanical reasoning as well as visuographic functioning. Recent reports have demonstrated that extracranial treatment with magnetic fields (MF) in the picoTesla range improves constructional abilities including visuoperceptive functions in Parkinsonian patients. To evaluate further the effects of these extremely weak MF on cognitive functions in Parkinsonism, I investigated in a 69 year old fully medicated Parkinsonian patient the influence of a single, extracranial application of MF on the patient's performance on the Complex Figure (copy and recall) as well as the Bicycle Drawing Test. Results of the trial showed that a 30 minute application of MF produced a dramatic improvement in the patient's ability to copy and recall the Complex Figure. This treatment was also associated with a marked improvement in the performance of bicycle drawing with reversal of the Parkinsonian micrographia. Collectively, these findings demonstrate that this treatment modality may reverse some of the cognitive impairments associated with Parkinsonism which usually are not improved by treatment with dopaminergic or anticholinergic medications.

Reversal of visual neglect in Parkinson's disease by treatment with picoTesla range magnetic fields

Visual neglect and impairment in perceptual motor or visuospatial tasks are among the most frequently encountered abnormalities in neuropsychological testing of patients with Parkinson's disease, being present in up to 90% of patients. It has been proposed that neglect reflects an attentional-arousal deficit induced by lesions that interrupt a cortical-limbic-reticular loop. Recently, we have reported that application of extracranial magnetic fields (MF) in the picoTesla range was efficacious in reducing the severity of the motor disability of Parkinsonism as well as improving some of the cognitive abnormalities associated with the disease such as visuoperceptive deficits. We now present a 61 year old fully medicated Parkinsonian patient in whom rapid reversal of left visual neglect as well as improvement in visuoconstructional (drawing) performance was noted immediately after a single external application of MF. We propose that this effect was related to enhancement of directed attention through a mechanism involving an interaction between the pineal gland, which is considered a "magnetosensor," and the reticular formation which mediates arousal and attention. This report demonstrates the efficacy of extremely weak MF in reversing some of the cognitive abnormalities in Parkinsonism, notably neglect and visuoperceptive deficits, which contribute significantly to impairment of the patient's daily living activities.

Rapid improvement of visuoperceptive functions by picoTesla range magnetic fields in patients with Parkinson's disease

Impairment in perceptual motor or visuospatial tasks is among the most frequently encountered abnormality in neuropsychological testing of patients with Parkinson's disease, being present in up to 90% of cases. Visuoperceptive deficits can result from cortical and subcortical lesions involving the right hemisphere, thalamus, and basal ganglia and are thought to reflect a defect in attentional-arousal mechanisms induced by lesions that interrupt a cortical-limbic-reticular activating loop. Clinically, the presence of visuoperceptive impairment may not be noted by Parkinsonian patients but may contribute to various disabilities including difficulty driving a vehicle and difficulties performing daily tasks which require intact visuospatial abilities (i.e., walking, dressing, drawing and copying designs). The present communication concerns two fully medicated Parkinsonian patients who responded to extracranial treatment with picoTesla range magnetic fields (MF), behaviorally and also demonstrated rapidly and dramatically enhanced visuoperceptive functions as demonstrated on various drawing tasks. These findings demonstrate the efficacy of extremely weak MF in enhancing cognitive functions in patients with Parkinson's disease.

The relationship between visuospatial ability and perceptual motor function in Parkinson's disease

To assess the contribution of visuoperceptual function to complex visuomotor responding in Parkinson's disease, 14 patients with idiopathic PD and 12 normal controls matched for age, education and general intellectual function were administered a visual tracing task. No difference was found between the groups on two visuoperceptual tests, the Benton Line Orientation test and a test of trajectory judgement. However, patients were significantly impaired in tracing a sawtooth design when two consecutive angles of the sawtooth were occluded. This impairment occurred in reproducing the basic form of the stimulus and not with accuracy of fine detail. These results suggest higher-order perceptual motor dysfunction independent of any breakdown in basic visuoperceptual processing or loss of fine motor control. It is concluded that Parkinsonian patients are unable to use sensory information accurately to plan and execute complex or new movements.

Executive function in Parkinson's disease: set-shifting or set-maintenance?

In order to distinguish impairment in set-shifting in Parkinson's disease (PD) from inability to inhibit distraction by stimuli that compete for attention, 18 nondemented patients with idiopathic PD and 13 normal controls equated for age and education, were administered the Odd-Man Out (OMO) test and the Stroop Color-Word Test. PD patients were significantly impaired on the OMO test but showed no evidence of interference during the Stroop test. Analysis of error patterns during the OMO test indicated that the requirement to repeatedly switch rules, rather than the requirement to maintain steady responding between rule switches, was responsible for impaired OMO performance. It is concluded that the OMO test is fundamentally a test of set shifting, rather than a test of set maintenance in PD. In addition, analysis of a larger sample of PD patients revealed a significant positive relationship between number and severity of extrapyramidal signs and error production on the OMO, and between the latter and global mental function. These relationships were independent of each other, suggesting that impairment in set-shifting function in PD may arise from pathology of the fronto-striatal system independently of changes in cognitive ability.

Set-shifting and spatial orientation in patients with Parkinson's disease

Individuals with Parkinson's disease were compared to normal control subjects on a series of widely used neuropsychological measures. The two groups were matched for gender, handedness, age, education, and occupation. The neuropsychological tests were chosen to measure two specific functions: (a) spatial orientation (i.e., measures of personal orientation, extrapersonal orientation, right/left orientation, and mental rotation), and (b) the ability to shift mental set (e.g., generating responses from alternating categories). The tests chosen to measure spatial orientation had no set-shifting component, and the tests chosen to measure set-shifting had no spatial orientation component. Multivariate statistical analyses revealed a significant difference between the subjects with Parkinson's disease and the control subjects on the measures of set-shifting ability. In contrast, no significant difference between the groups was observed on the measures of spatial orientation. These results are discussed in terms of the current speculation in the literature regarding the relationship between set-shifting deficits and a disruption of dopaminergic fibers to the prefrontal cortex in Parkinson's disease.

Prism adaptation and other tasks involving spatial abilities in patients with Parkinson's disease, patients with frontal lobe lesions and patients with unilateral temporal lobectomies

Patients in the early stages of Parkinson's disease were compared with patients who had sustained damage specific to either the frontal or temporal lobes and normal controls on a delayed alternation task, a test of the left right orientation and a prism adaptation task. On the former two tasks age accounted for more of the variability in performance than did site of brain lesion. However, patients with frontal lobe, right temporal lobe or basal ganglia damage were significantly impaired on the adaptation task. The results are discussed with regard to "switching", "sequencing" and "internal guidance" of movement hypotheses.

Parkinson's disease: a conceptualization of neuropsychological deficits within an information-processing framework

Parkinson's disease patients are frequently impaired in a variety of neuropsychological tasks involving memory, perceptual motor performance and cognitive flexibility. Although various theories have been forwarded to explain specific impairments, few attempts have been made to account for all the deficits within a single theoretical framework. Furthermore, the frequent occurrence of dementia, the adverse side effects of medication and the motor symptoms of the disease tend to interfere with neuropsychological performance. This has hindered the clear delineation of the neuropsychological profile of Parkinsonian patients. The present paper examines the evidence for intellectual deficits in non-demented Parkinson's disease patients. A number of problems inherent in cognitive research on Parkinson's disease are discussed. The contribution of dementia, motor symptom severity and medication in the expression of these intellectual impairments is examined. It is suggested that many of the neuropsychological deficits described in Parkinson's disease may result from a common underlying deficit in some aspect of information processing. Although it is not possible to pinpoint the precise mechanism(s) involved on the basis of the available evidence, several possibilities are suggested by cognitive and electrophysiological data.

Major depression in Parkinson's disease and the mood response to intravenous methylphenidate: possible role of the "hedonic" dopamine synapse

The euphoric response to equivalent doses of intravenous methylphenidate (MTP) was assessed in a group of 13 Parkinsonian patients affected by major depression, in a group of 11 nondepressed Parkinsonians, in a group of 14 nonparkinsonian subjects suffering from major depression, and finally in a group of 12 controls with no CNS or psychiatric disease. Subjects of all four groups were matched for age, sex and other main characteristics. Depressed and nondepressed Parkinsonians were also matched for duration and severity of illness, and for the type of antiparkinsonian treatment. The response to MTP was evaluated in the context of a double-blind, placebo-controlled study. Parkinsonian patients with major depression exhibited a significant lack of sensitivity to the euphoriant effects of MTP, in comparison with the other three groups. Euphoria produced by central stimulants has been shown to depend on the activity of a dopamine synapse in humans, which is thought to be situated at the limbic terminals of dopamine neurons located in the ventral tegmental area. Degeneration of this system may have predisposed our Parkinsonian patients to major depression.

Prism adaptation in Parkinson's disease

Prism adaptation is impaired by lesions in the basal ganglia in non-human primates, suggesting that this area is involved in this form of visuomotor learning. We investigated the ability of patients with Parkinson's disease to prism adapt. Patients and controls wore prisms which deflected vision laterally by 11 degrees. After baseline testing with a localisation task that permitted no feedback about performance accuracy, prism adaptation was tested at 4 minute intervals over a 28 minute trial. All subjects erred initially, reaching too far to the left of the target, but a separate pointing task encouraged adaptation and reaching error decreased at a similar rate in Parkinsonians and controls. Immediately after the prisms were removed, all subjects reached to the right of the target. This negative after effect was present in controls but not patients when assessed 4 minutes later, suggesting that the patients could not maintain the new sensorimotor relationship imposed by the prisms after their removal. This is similar to performance on visuospatial and executive tasks in Parkinsonians, where ongoing behaviour cannot be modulated without external guidance.

Intellectual impairment in Parkinson's disease: clinical, pathologic, and biochemical correlates

The prevalence of overt dementia in 27 studies representing 4,336 Parkinson's disease (PD) patients was 39.9%. The studies reporting the highest incidence of intellectual impairment (69.9%) used psychologic assessment techniques, whereas studies identifying the lowest prevalence of dementia (30.2%) depended on nonstandardized clinical examinations. Neuropsychologic investigations reveal that PD patients manifest impairment in memory, visuospatial skills, and set aptitude. Language function is largely spared. Intellectual deterioration in PD correlates with age, akinesia, duration, and treatment status. Neuropathologic and neurochemical observations demonstrate that PD is a heterogeneous disorder: the classic subcortical pathology with dopamine deficiency may be complicated by atrophy of nucleus basalis and superimposed cortical cholinergic deficits, and a few patients have the histopathologic hallmarks of Alzheimer's disease. Mild intellectual loss occurs with the classic pathology, and the more severe dementia syndromes have cholinergic alterations or Alzheimer's disease. Thus, PD includes several syndromes of intellectual impairment with variable pathologic and neurochemical correlates.

Mood changes associated with "end-of-dose deterioration" in Parkinson's disease: a controlled study

Fluctuations of mood and psychic activation were assessed in relation to "mobile" and "immobile" periods in 18 patients with Parkinson's disease presenting typical "end-of-dose deterioration". Twelve subjects with chronic but active rheumatoid arthritis presenting increased physical disability due to severe morning joint stiffness with a repetitive pattern of mobile and immobile periods acted as controls. The overall degree of disability and its fluctuations were close enough in the two groups for fair comparison of changes in affective behaviour. Temporary immobility was accompanied by adverse changes of mood and activation, which were significantly more marked in the Parkinson's disease group than in the controls, though to a lesser extent in those Parkinson's disease patients rated depressed even in their mobile periods. The possible correlation between mood changes and fluctuations of central dopaminergic function in the Parkinson's disease patients is discussed.

Prognostic implications of the motor symptoms of Parkinson's disease with respect to clinical, computertomographic and psychometric parameters

Forty-four Parkinson patients (19 patients of the rigid-akinetic type, 13, of the rigid-akinetic-tremor type, and 12, of the tremor type) were included in a study in order to analyse correlations of the expression of the motor symptoms tremor, rigidity, akinesia, with other clinical parameters, computertomographic aspect of brain atrophy and psychometrically assessed cognitive parameters. Rigidity and akinesia are significantly positively correlated with the severity of motor dysability, stage of the disease, and brain atrophy, as is akinesia with a history of pharmacotoxic psychosis. Tremor is significantly negatively correlated with motor dysability, stage of the disease, and history of pharmacotoxic psychosis. Akinesia is correlated with visuomotor dysfunction (tested with Bender Gestalt Test) and rigidity with the depression score (Zung scale). The tremor type is favorable, the rigid-akinetic type unfavorable with respect to motor disability and psychosis.

The concept of subcortical and cortical dementia: another look

The subcortical dementias such as progressive supranuclear palsy, Huntington's disease, and Parkinson's disease are said to be characterized by the presence of slowed mentation, apathy, and the absence of aphasia, agnosia, and apraxia, symptoms that are claimed to be more common in cortical dementias such as Alzheimer's disease. Conceptual problems (such as vagueness of terms and difficulties with symptom definition) and methodological problems (such as improper matching of comparison groups and inadequate assessment techniques) found in currently available studies require a reappraisal of this classification of dementias into cortical and subcortical forms. A review of recent clinical, neuropathological, and neurochemical studies offers little support for this classification system, although adequate systematic studies have not been performed.