The Visuo-Motor Attention Test in Boys with Attention Deficit Hyperactivity Disorder (ADHD): Methylphenidate-Placebo Randomized Controlled Trial.

To assess the visuomotor attention ability in children with ADHD and controls and their response to placebo and Methylphenidate (MPH) treatment. 36 boys with ADHD and 36 age matched typical controls were administered the visuomotor attention test (VMAT) as a baseline and following a week of MPH(IR) or placebo administered to the study group, in a randomized crossover design. A significant difference between the study and control groups was found on several VMAT measures. No performance difference between ADHD dimensional sub-types was observed at the baseline assessment. Under MPH treatment a significant improvement in VMAT measures was observed and particularly in the combined and predominantly hyperactive (C\HI) type. The VMAT results obtained in the present study are consistent with previous findings. ADHD subtypes appear similarly short of visuomotor attention resources; a visuomotor test can be used in the assessment of gains derived from MPH treatment.

Auditory and Visual Executive Functions in Children and Response to Methylphenidate: A Randomized Controlled Trial.

Objectives: The aim of the study was to assess auditory and visually based executive functions (EFs) and the effect of methylphenidate (MPH) in children with ADHD. Methods: Thirty-six boys between the ages of 8.3 and 9.7 years with ADHD and 36 matched controls were included. The study group was randomized into MPH and placebo for 7 days each in a crossover design. A Cued Choice Reaction Time (CCRT) test that included incongruent cuing was administered at baseline and following 1 and 2 weeks. Results: The difference between the study and control groups was more evident with visual cues and incongruent cuing. Increased gains by children with predominantly hyperactive-impulsive\combined (HI\C) type of ADHD were observed under MPH. Conclusions: The differences between children with ADHD and typical children are more pronounce under incongruent auditory cuing . The gains attributable to MPH are more specific to tasks involving auditory and visual EFs and in children with HI\C type ADHDs.

The choice of freely preferred cadence by trained nonprofessional cyclists may not be characterized by mechanical efficiency.

BACKGROUND: Most cycling studies involve professional cyclists. Because training may affect riding style, it is of interest to determine the physiological basis for the personal choice of cycling cadence in nonprofessional cyclists. METHODS: Eleven nonprofessional (5.2±1.7-year-riding experience) male road cyclists, aged 35.0±11.0 years, underwent four separate laboratory test sessions. The first two sessions included habituation, anthropometry, V˙O2max,$\dot V{{\text{O}}_{\text{2}}}{\text{max}},$ and lactate threshold (LaTH) measurements. Freely preferred cadence at LaTH was determined during the second session (mean±SD=94.7±2.9 rev·min-1). During the third and fourth sessions participants performed LaTH tests at 60 and 95 rev·min-1 in a randomized order, with power output (PO) increments of 25 W every 4 min, up to ~90% of V˙O2max.$\dot V{{\text{O}}_{\text{2}}}{\text{max}}{\text{.}}$ Results: V˙O2,$\dot V{{\text{O}}_{\text{2}}},$ expired ventilation (V˙E),$({\dot V_E}),$ blood lactate (La), and calculated net mechanical efficiency (MEnet) rose with increased PO. At 95 rev·min-1, V˙O2, V˙E,$\dot V{{\text{O}}_2},{\text{ }}{\dot V_{\text{E}}},$ and La were significantly higher than at 60 rev·min-1 at all POs. MEnet at 95 rev·min-1 was lower than at 60 rev·min-1. Mean PO attained at LaTh did not differ significantly between 60 and 95 rev·min-1 (220.9±29.0 and 214.5±9.2 W, respectively). La values at LaTH were higher at 95 rev·min-1 than at 60 rev·min-1 (3.01±0.17 vs. 2.10±0.13 mM, p<0.05, respectively). CONCLUSIONS: Our findings indicate that mechanical and physiological efficiencies may not determine the choice of cycling cadence by nonprofessional cyclists. This choice may reflect the need to maintain endurance at the expense of riding at a lower than optimal riding efficiency.

Subthalamic nucleus deep brain stimulation does not improve visuo-motor impairment in Parkinson's disease.

OBJECTIVE: To evaluate how bilateral subthalamic nucleus deep brain stimulation (STN-DBS) affects visuo-motor coordination (VMC) in patients with Parkinson's disease (PD). BACKGROUND: VMC involves multi-sensory integration, motor planning, executive function and attention. VMC deficits are well-described in PD. STN-DBS conveys marked motor benefit in PD, but pyscho-cognitive complications are recognized and the effect on VMC is not known. METHODS: Thirteen PD patients with bilateral STN-DBS underwent neurological, cognitive, and mood assessment before VMC testing with optimal DBS stimulation parameters ('on-stimulation') and then, on the same day without any medication changes, after DBS silencing and establishing motor function deterioration ('off-stimulation'). Twelve age-matched healthy controls performed 2 successive VMC testing sessions, with a break of similar duration to that of the PD group. The computer cursor was controlled with a dome-shaped 'mouse' hidden from view that minimized tremor effects. Movement duration, hand velocity, tracking continuity, directional control variables, and feedback utilization variables were measured. MANOVA was performed on (1) clinically measured motor function, (2) VMC performance and (3) mood and attention, looking for main and interaction effects of: (1) group (controls/PD), (2) test-order (controls: first/second, PD: on-stimulation/off-stimulation), (3) path (sine/square/circle) and (4) hand (dominant/non-dominant). RESULTS: Unified PD Rating Scale (UPDRS) Part III worsened off-stimulation versus on-stimulation (mean: 42.3 versus 21.6, p = 0.02), as did finger tapping (p = 0.02), posture-gait (p = 0.01), upper limb function (p<0.001) and backwards digit span (p = 0.02). Stimulation state did not affect mood. PD patients performed worse in non-velocity related VMC variables than controls (F(5,18) = 8.5, p<0.001). In the control group there were significant main effects of hand (dominant/non-dominant), path (sine/square/circle) and test-order (Test_1/Test_2). In the PD group, hand and path effects, but no test-order (on-stimulation/off-stimulation), were found. CONCLUSIONS: 'Low-level' clinically-measured motor function responds to STN-DBS but 'high-level' motor and cognitive functions relating to VMC may be unresponsive to STN-DBS.

Visuo-motor coordination deficits and motor impairments in Parkinson's disease.

BACKGROUND: Visuo-motor coordination (VMC) requires normal cognitive executive functionality, an ability to transform visual inputs into movement plans and motor-execution skills, all of which are known to be impaired in Parkinson's disease (PD). Not surprisingly, a VMC deficit in PD is well documented. Still, it is not known how this deficit relates to motor symptoms that are assessed routinely in the neurological clinic. Such relationship should reveal how particular motor dysfunctions combine with cognitive and sensory-motor impairments to produce a complex behavioral disability. METHODS AND FINDINGS: Thirty nine early/moderate PD patients were routinely evaluated, including motor Unified Parkinson's Disease Rating Scale (UPDRS) based assessment, A VMC testing battery in which the subjects had to track a target moving on screen along 3 different paths, and to freely trace these paths followed. Detailed kinematic analysis of tracking/tracing performance was done. Statistical analysis of the correlations between measures depicting various aspects of VMC control and UPDRS items was performed. The VMC measures which correlated most strongly with clinical symptoms represent the ability to organize tracking movements and program their direction, rather than measures representing motor-execution skills of the hand. The strong correlations of these VMC measures with total UPDRS score were weakened when the UPDRS hand-motor part was considered specifically, and were insignificant in relation to tremor of the hand. In contrast, all correlations of VMC measures with the gait/posture part of the UPDRS were found to be strongest. CONCLUSIONS: Our apparently counterintuitive findings suggest that the VMC deficit pertains more strongly to a PD related change in cognitive-executive control, than to a reduction in motor capabilities. The recently demonstrated relationship between gait/posture impairment and a cognitive decline, as found in PD, concords with this suggestion and may explain the strong correlation between VMC dysfunction and gait/posture impairment. Accordingly, we propose that what appears to reflect a motor deficit in fact represents a multisystem failure, dominated by a cognitive decline.

Adaptation to cyclic stance perturbations in Parkinson's disease depends on postural demands.

The postural reactions of 10 moderate PD patients and 10 age matched controls were studied during stance on a sinusoidally back and forth moving platform during 5 blocks of 10, 1-min trials. Free stance was followed by weight bearing, lowering or raising the center of gravity (COG) by 10%. Next, a book was balanced on the head and finally, forward inclination was constrained. Normal stance strategy, including predictive muscle responses was found during free stance. Modifying COG height caused little response changes. Stance strategy became abnormal when head trajectory or forward inclination was restricted, indicating that ability to generate a nonstandard multi-joint stance strategy, rather than production of adequate stabilizing forces, is impaired in moderate, medicated PD patients.

Visuomotor tracking related to attention-deficit hyperactivity disorder (ADHD).

Deficient visuomotor tracking in children with attention-deficit hyperactivity disorder (ADHD) has been described, but the specific influence of attention on this deficit has not yet been elucidated. The present study compares visuomotor tracking under different conditions of attentional loading in children with ADHD with that of age-matched controls. A computerized visuomotor attentional tracking test that incorporated several levels of distraction was administered to 13 typical children. The same test, as well as a standard Matching Familiar Figures Test and the Proteus Maze test, was administered to 32 children with ADHD and 21 control children. Significant differences between children with ADHD and controls in visuomotor attentional tracking indices that relate to pacing and the accuracy of the tracking movements were observed under all levels of distraction. In parallel, a significant performance decrement was observed in all subjects once distraction was introduced. Discriminant analysis, based on the visuomotor attentional tracking test findings, resulted in correct classification of 92.3% of the typical children and 46% of the children with ADHD. Significant correlations between Matching Familiar Figures Test latency, as well as errors and visuomotor attentional tracking indices, were noted among children with ADHD when the visuomotor attentional tracking did not involve distraction. Under distraction, these correlations extended to the control group as well. In conclusion, visuomotor tracking appears to reflect the availability of attentional resources in general and is significantly affected by the presence of ADHD in particular. These results have potential implications related to the evaluation of children with ADHD on and off drugs.

Recruitment of attentional resources during visuomotor tracking: effects of Parkinson's disease and age.

The ability to recruit attentional resources during distracted tracking was studied in 19 moderate PD patients, 21 healthy elderly subjects and 20 young controls. All subjects tracked a 1-cm circle that moved across a computer screen along a sinusoidal path (training) and along a circular path (testing). Tracking consisted of maintaining a dot cursor within the target by moving an unseen manipulandum across a digitizing tablet. Distraction consisted of adding one or three, colored 12-mm circles that moved around and intersected with the target circle, and one or three dots that moved around and intersected with the subject-controlled cursor. The performance of tasks with a low level of distraction (one dot and one circle distractor) and of tasks with a high level of distraction (three dot and three circle distractors) was compared to performance with no distraction. The elderly and young controls did not differ in the baseline task. Both groups surpassed the patients, who failed to keep pace with the target, despite preserved ability to attain the necessary movement speed. Under a low level of distraction, the ability to adjust the direction of hand movement diminished in both control groups, but task management was unaltered. In the patients adjustment of hand movement direction lowered, as in the controls, but task management reduced significantly. Under a high level of distraction, all groups showed further decrement in both aspects of task performance. We conclude that PD, but not age, significantly reduces the attentional resources required for administrative control of tracking, which are associated with prefrontal function.

Dopamine-transporter imaging and visuo-motor testing in essential tremor, practical possibilities for detection of early stage Parkinson's disease.

BACKGROUND: Essential tremor (ET) is often an alternative diagnosis to Parkinson's disease (PD) and some ET patients may later develop PD. Unlike the former, PD patients have deficient visuo-motor coordination (VMC). Recently, we have attempted to exploit this difference in order to detect PD in ambiguous neurological cases. OBJECTIVE: To assess the possibility of using VMC testing for screening ET patients prior to [123I]-FP-CIT SPECT imaging. METHODS: Ten clinically diagnosed ET patients who showed deficient VMC were subjected to [123I-FP-CIT] SPECT imaging. We expected these patients to show subnormal striatal ligand uptake, as in PD. RESULTS: We found decreased [123I]-FP-CIT uptake in 80% of the patients. A significant correlation between ligand uptake and VMC was observed. CONCLUSIONS: Impaired VMC is a pertinent indication for further SPECT imaging in patients with ET, in order to establish a diagnosis of incipient PD.

Antipsychotic-induced rabbit syndrome: epidemiology, management and pathophysiology.

Rabbit syndrome is an antipsychotic-induced rhythmic motion of the mouth/lips, resembling the chewing movements of a rabbit. The movement consists of a vertical-only motion, at about 5Hz, with no involvement of the tongue. Usually, the involuntary movements associated with rabbit syndrome appear after a long period (in most cases months or years) of antipsychotic treatment; however, a few patients with the syndrome have had treatment histories with no antipsychotic involvement. The reported prevalence of rabbit syndrome ranges from 2.3 to 4.4% of patients treated with typical antipsychotics. There have been isolated reports of rabbit syndrome in patients treated with the atypical agents risperidone and clozapine. Patients with rabbit syndrome are most often misdiagnosed as having oral tardive dyskinesia. In such cases the key for correct diagnosis is the involvement of tardive tongue movements, which does not occur in rabbit syndrome. The treatment of rabbit syndrome is empirical, reflecting poor understanding of its neuropathology. The first step is to reduce the amount of antipsychotic treatment as much as possible. However, since, in most cases, full withdrawal of antipsychotic treatment is impossible, the syndrome cannot be completely abolished without additional measures. The next stage of treatment involves specific drugs that aim to control the syndrome. Anticholinergic drugs are the best known treatment. Rabbit syndrome does not respond to treatment with levodopa or dopamine agonists. The most striking aspect of this syndrome is its specificity. Rabbit syndrome affects only the buccal region, and within this area it involves a highly stereotyped involuntary movement. This immediately focuses attention on the basal ganglia, in particular the substantia nigra pars reticulata, which is also implicated in oral dyskinesia. Continuing neurophysiological and pharmacological research of the basal ganglia holds the key to better understanding and treatment of this syndrome in the coming years.

Response selection and execution in patients with Parkinson's disease.

Different studies report diverse, sometimes conflicting findings, regarding the ability of Parkinson's disease (PD) patients to benefit from advanced cuing in choice reaction time (RT). Thus, conclusions about the changed state of underlying processes such as set formation, motor programming and motor initiation are not certain. In the present study, visual choice RT testing that utilized brief (100 ms) color signals (red/blue), was followed by auditory choice reaction time (CRT) testing with brief (100 ms) low/high pitch sound stimuli. Response consisted of either index or middle finger flexion. The signals were then combined so that the color stimuli cued the sound stimuli with an 800-ms interstimuli interval. Cuing validity was reduced from 100% during training to 76% during final testing. In addition, the same sound stimuli were presented randomly, without visual cuing, in which case response should have been suppressed. Tested subjects include 19 moderate PD patients, 21 elderly controls and 20 young controls. The patients did not differ from the controls in error rate but were slower to respond, except under 100% congruent cuing, indicating that their extended RT in CRT results from slowed stimulus-response linking and not from impaired motor initiation/execution. In the final condition patients showed no perseverance and demonstrated normal speed of set shifting in incongruent trials.

Visuo-motor coordination is normal in patients with major depression.

Depression and Parkinson's disease (PD) are strongly associated with each other. Similarly, deficient visuo-motor coordination (VMC) accompanies PD from its earliest clinical stages. This double association suggests that a VMC dysfunction would be found in patients with major depression. Previous reports are ambiguous on this matter. Therefore, the present study was undertaken in order to determine whether MD patients pass or fail a VMC test on which PD patients are known to be deficient.Sixty-five MD patients were tested. Fifty-four (83%) had normal VMC. VMC was found to be independent of age, disease duration, severity of depression, or treatment. A deficit was found in 12 patients (17%). In this group too, VMC capabilities did not correlate with depression, or its treatment.These results negate an effect of depression, its accompanying frontal cortical changes, or its treatment on VMC. We propose that abnormal VMC in depression indicates coexisting illness, including possible preclinical PD.

Impaired visuomotor function in schizophrenic patients compared with control subjects.

Visuomotor function was studied in 36 schizophrenic patients treated with atypical antipsychotics and in 22 control subjects. Patients showed significant disturbances in ability to control movement direction when tracing objects on screen and in keeping pace with a moving target in tracking tests. The impairments were not related to medication dose or to extrapyramidal side effects. Visuomotor impairment may be part of illness-related pathology in schizophrenia.