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PubMed1998

Periodic limb movement disorder and restless legs syndrome in children with attention-deficit hyperactivity disorder.

Sleep disruption can lead to symptoms of attention-deficit hyperactivity disorder (ADHD) in children. Since periodic limb movement disorder and/or restless legs syndrome can cause sleep disruption, we assessed whether these two specific sleep disorders are likely to occur in children with ADHD. We asked a series of 69 consecutive parents of children with ADHD questions about the symptoms of periodic limb movement disorder. Based on a positive response to these periodic limb movement disorder queries, 27 children underwent all-night polysomnography. Eighteen children (aged 2 to 15 years) of the 27 (26% of the 69 children with ADHD) had 5 or more periodic leg movements in sleep per hour of sleep and had complaints of sleep disruption, thus fulfilling the criteria for periodic limb movement disorder. A comparably age- and sex-matched group of children referred to a sleep laboratory for sleep complaints but without ADHD showed only a 5% prevalence (2 of 38 subjects) of periodic leg movements in sleep (P=.017). Eight of the 18 children with ADHD and periodic limb movement disorder and one of the two control patients with periodic limb movement disorder had both a personal and parental history of restless legs syndrome symptomatology. This study further documents the occurrence of periodic limb movement disorder and restless legs syndrome in children and is the first large-scale study establishing a possible comorbidity between ADHD and periodic limb movement disorder. We propose that the sleep disruption associated with periodic limb movement disorder and restless legs syndrome and the motor restlessness of restless legs syndrome while awake could contribute to the inattention and hyperactivity seen in a subgroup of ADHD-diagnosed children.

Adolescent↗
PubMed2005

An automated system for measuring parameters of nematode sinusoidal movement.

BACKGROUND: Nematode sinusoidal movement has been used as a phenotype in many studies of C. elegans development, behavior and physiology. A thorough understanding of the ways in which genes control these aspects of biology depends, in part, on the accuracy of phenotypic analysis. While worms that move poorly are relatively easy to describe, description of hyperactive movement and movement modulation presents more of a challenge. An enhanced capability to analyze all the complexities of nematode movement will thus help our understanding of how genes control behavior. RESULTS: We have developed a user-friendly system to analyze nematode movement in an automated and quantitative manner. In this system nematodes are automatically recognized and a computer-controlled microscope stage ensures that the nematode is kept within the camera field of view while video images from the camera are stored on videotape. In a second step, the images from the videotapes are processed to recognize the worm and to extract its changing position and posture over time. From this information, a variety of movement parameters are calculated. These parameters include the velocity of the worm's centroid, the velocity of the worm along its track, the extent and frequency of body bending, the amplitude and wavelength of the sinusoidal movement, and the propagation of the contraction wave along the body. The length of the worm is also determined and used to normalize the amplitude and wavelength measurements. To demonstrate the utility of this system, we report here a comparison of movement parameters for a small set of mutants affecting the Go/Gq mediated signaling network that controls acetylcholine release at the neuromuscular junction. The system allows comparison of distinct genotypes that affect movement similarly (activation of Gq-alpha versus loss of Go-alpha function), as well as of different mutant alleles at a single locus (null and dominant negative alleles of the goa-1 gene, which encodes Go-alpha). We also demonstrate the use of this system for analyzing the effects of toxic agents. Concentration-response curves for the toxicants arsenite and aldicarb, both of which affect motility, were determined for wild-type and several mutant strains, identifying P-glycoprotein mutants as not significantly more sensitive to either compound, while cat-4 mutants are more sensitive to arsenite but not aldicarb. CONCLUSIONS: Automated analysis of nematode movement facilitates a broad spectrum of experiments. Detailed genetic analysis of multiple alleles and of distinct genes in a regulatory network is now possible. These studies will facilitate quantitative modeling of C. elegans movement, as well as a comparison of gene function. Concentration-response curves will allow rigorous analysis of toxic agents as well as of pharmacological agents. This type of system thus represents a powerful analytical tool that can be readily coupled with the molecular genetics of nematodes.

Acetylcholine↗
PubMed2003

Vestibular signals of posterior parietal cortex neurons during active and passive head movements in macaque monkeys.

The posterior parietal cortex may function as an interface between sensory and motor cortices and thus could be involved in the formation of motor plans as well as abstract representations of space. We have recorded from neurons in the intraparietal sulcus, namely, the ventral and medial intraparietal areas (VIP and MIP, respectively), and analyzed their head-movement-related signals in relation to passive and active movements. To generate active head movements, we made the animals track a moving fixation spot in the horizontal plane under head-free conditions. When under certain circumstances the animals were tracking the fixation spot almost exclusively via head movements, a clear correlation between neuronal firing rate and head movement could be established. Furthermore, a newly employed paradigm, the "replay method," made available direct comparison of neuronal firing behavior under active and passive movement conditions. In such case, the animals were allowed to make spontaneous head movements in darkness. Subsequently, the heads were fixed and the previously recorded active head-movement profile was reproduced by a turntable as passive stimulation. Neuronal responses ranged from total extinction of the vestibular signal during active movement to presence of activity only during active movement. Furthermore, in approximately one-third of the neurons, a change of vestibular on-direction depending on active versus passive movement mode was observed, that is, type I neurons became type II neurons, etc. We suggest that the role of parietal vestibular neurons has to be sought in sensory space representation rather than reflex behavior and motor control contexts.

Animals↗
PubMed2006

Developmental changes in unimanual and bimanual aiming movements.

The aim of this study was twofold: (a) analyze the development of reaction time (RT) and movement time (MT) for bimanual and unimanual movements and (b) investigate the interaction of age and sex on the changes in RT and MT. Participants (5-, 8-, and 11-year-olds) were asked to aim at target buttons under three conditions of movement: unimanual, bimanual symmetrical, and bimanual nonsymmetrical. As expected, RTs for bimanual symmetrical movements were shorter than RTs for unimanual and bimanual nonsymmetrical movements in the 5-year-olds. By the age of 8, bimanual nonsymmetrical movements still yielded longer RTs than unimanual and bimanual symmetrical movements, which no longer differed from each other. Regarding MT, in the 2 younger groups there was an advantage of unimanual over bimanual symmetrical movements. The latter were executed faster than nonsymmetrical movements at all ages. These results suggest that the evolution of RT and MT with age reflects development of interhemispheric transfer of information. It appears that the functional improvement of such transfer, which depends on the corpus callosum, progressively enables contralateral motor inhibition and the coordination of complex bilateral movements. The exchange of movement feedback information could mature more slowly than that of feed-forward information, explaining the extended time course of MT evolution.

Age Factors↗
PubMed1999

Movement disorders following nonfunctional neurosurgery.

OBJECT: Knowledge is scarce about movement disorders that follow neurosurgical operations other than functional stereotactic surgery. The cases of 14 patients who suffered from movement disorders secondary to craniocerebral or spinal surgery are analyzed. None of these patients was initially treated by any of the authors. METHODS: Twelve patients underwent surgery for cerebral diseases. Nine of these patients harbored tumors and three patients had neurovascular disorders. Two patients underwent spinal surgery for cervicothoracic ependymoma or for multiple cervical disc herniations. Twelve of the 14 patients had immediate postoperative side effects such as hemiparesis, ataxia, and somnolence. In all but two patients, movement disorders became manifest only after a delay. Dystonic movement disorders developed in eight patients, unilateral tremors in three patients, unilateral facial myokymia in one patient, and hemichorea-hemiballism in two patients. The mean delay of onset for tremor was 5 weeks and that for dystonic movement disorders was 5.5 months. Movement disorders were transient in three patients; however, they were persistent in 11 patients at a mean follow-up period of 5 years. These movement disorders caused marked persistent disability in four patients. Lesions of the contralateral striatum were identified in patients with dystonic syndromes and lesions of the dentatothalamic outflow in patients with tremors. In three patients who had postoperative basal ganglia lesions after partial removal of astrocytomas, tumor regrowth was later documented. Medical treatment in patients with persistent movement disorders rendered only limited benefit. Two patients improved with botulin injections. In one patient postoperative hemidystonia was alleviated by contralateral thalamotomy. CONCLUSIONS: Dystonic syndromes and tremors are the most common movement disorders that occur after craniocerebral and spinal surgery. Postoperative movement disorders can lead to various degrees of functional disability. The pathoanatomical correlations are similar to those described in other patients with secondary movement disorders.

Adolescent↗
PubMed1999

[Three-dimensional analysis of eye movements induced by off-vertical axis rotation].

Off-vertical axis rotation (OVAR) is a method to stimulate the otolith organ. In order to elucidate the function of the otolith organ, we analyzed three-dimensional eye movements by video-oculographic technique during OVAR in 30 normal subjects. The eye movements induced by OVAR stimulation have two components: a constant horizontal deviation in the direction opposite to the rotation known as the bias component, and sinusoidal amplitude changes of eye movements known as the modulation component. Modulation components were detected in the horizontal, vertical, and torsional eye movements, but the bias components were only detected in the horizontal eye movements. The modulation components may compensate for changes in head orientation with respect to gravity. Since the bias component is caused by the velocity storage mechanism, the lack of bias components in vertical and torsional eye movements may suggest its specific relation to only horizontal eye movements. Our results also demonstrated that torsional and horizontal eye movements may originate from the utricle, whereas vertical eye movement may originate from the saccule. However, a lag phase between torsional and horizontal eye movements suggests that the most effective direction for stimulation of these two eye movements may be different.

Adult↗
PubMed1990

Shoulder shrug--a prognostic sign for recovery of hand movement after stroke.

A new clinical sign with prognostic significance for recovery of hand movements after stroke is described. Thirty-two patients with hemispheric cerebrovascular accident were assessed to determine whether the ability to shrug the hemiplegic shoulder at initial assessment correlated with the recovery of hand movements. The results of 29 of these patients with poor hand movements at initial assessment were analysed. Of 18 patients with absent shoulder shrug, only two patients (11%) showed return of good active movements in the involved hand at final evaluation, whereas eight (73%) of 11 patients who could shrug the hemiplegic shoulder at initial assessment went on to recover good movements in the hand (P = 0.00). In a subgroup of patients who demonstrated only synergistic flexion of fingers in the hemiplegic hand, one of five patients with absent shoulder shrug showed good hand movements at the final assessment in contrast to six of seven patients who initially could shrug the hemiplegic shoulder. Only one of 15 patients who showed total absence of hand movements at the initial assessment had a return of good hand movements. The data suggest that clinical assessment of shoulder shrug is a good prognostic indicator for recovery of voluntary movements in the hemiplegic hand especially when any hand movement, even if it is only synergistic finger flexion, is present at initial assessment. Total absence of hand movements at initial assessment is a poor prognostic sign.

Adult↗
PubMed1991

Temporal patterns of muscle activation for arm movements in three-dimensional space.

Little is known about the patterns of muscle activation that subserve arm movement in three-dimensional space. In this study, activation patterns of seven arm muscles were related to the spatial direction of human arm movement. Twenty movement directions defined two orthogonal vertical planes in space. The arm movements were moderately paced; each movement lasted approximately 500 msec. New techniques of EMG analysis were developed to describe the temporal pattern of muscle activation. For each muscle, a principal component analysis revealed a common phasic and tonic waveform for all directions of movement, within one plane. A temporal shifting procedure based on best covariance values revealed activation delays associated with different movement directions. The results show a consistent pattern of temporal shifting of the common waveform for movements in different directions. Coupled with past results showing that activation amplitude is a function of the cosine angle of movement or force direction, the present results suggest a relatively simple control strategy for mechanically complex arm movements: neural circuits produce a common phasic and tonic activation waveform that is scaled in amplitude and delayed in time, depending on the desired movement direction.

Arm↗
PubMed1990

Making arm movements within different parts of space: dynamic aspects in the primate motor cortex.

The activity of 176 individual cells in the arm area of motor cortex (areas 4 and 6) was studied while monkeys made arm movements of similar direction within different parts of extrapersonal space. The behavioral paradigm used was a 3-dimensional reaction-time task aimed at dissociating the direction of movement, which remained similar across the work space, from the patterns of muscular activity and the angular joint excursions necessary to perform these movements. In agreement with other studies (Georgopoulos et al., 1982; Schwartz et al., 1988), we found that, within a given part of space, the activity of 169 (96.0%) cells studied increased most for a given preferred direction and less for other directions of movement. This change was graded in an orderly fashion. We further analyzed the orientation in space of the cells' preferred directions under the differing conditions of the task. We found that, as movements with similar trajectories were made within different parts of space, the cells' preferred directions changed spatial orientation. This change was of different magnitudes for different cells, but at the level of the population, it followed closely the changes in orientation of the arm necessary to perform the movements required by the task. Movement population vectors (Georgopoulos et al., 1983, 1986, 1988) computed from cell activity proved to be good predictors of movement direction regardless of where in space the movements were performed. These results indicate that motor cortical cells can code direction of movement in a way which is dependent on the position of the arm in space. The data are discussed in relation to the existence of mechanisms which facilitate the transformation between extrinsic and intrinsic coordinates. These transformations are necessary to perform arm movements to visual targets in space.

Animals↗
PubMed1989

A comparison of movement direction-related versus load direction-related activity in primate motor cortex, using a two-dimensional reaching task.

Shoulder joint-related motor cortex cells show continuously graded changes in activity, centered on a preferred movement direction, during active arm movements in 8 directions away from a central starting position (Georgopoulos et al., 1982). We demonstrate here that many of these cells show similar large continuously graded changes in discharge when the monkey compensates for inertial loads which pull the arm in 8 different directions. These load-dependent discharge variations are typically unimodal, centered on one load direction called the cell's load axis, and are often sufficiently continuous, symmetric, and broad as to show a good fit to a sinusoidal curve. A vectorial representation of cell activity indicates that the pattern of load-dependent activity changes in the population forms a signal whose direction is appropriate to compensate for the loads. The responses of single cells to different combinations of movement and load direction are often complex. Nevertheless, the mean activity of the sample population under any condition of movement direction and load direction can be described reasonably well by a simple linear summation of the movement-related discharge without any loads, and the change in tonic activity of the population caused by the load, measured prior to movement. The strength of the load-dependent discharge variation differs among cells. Cells can be sorted into 2 phasic and 2 tonic groups that show differing degrees of sensitivity to loads. In particular, it was found that the greater the degree of cell discharge variation associated with different actively maintained limb postures, the greater the activity changes caused by loads. No similar correlation was found for the degree of discharge variation during movement. Preliminary evidence suggests that phasic and tonic cell groups may be spatially segregated in the motor cortex. These observations are consistent with the idea that there exists in the motor cortex activity encoding aspects of movement kinematics, as well as movement dynamics. These observations are in agreement with studies of more distal arm joints, showing that the activity of certain motor cortex cells varies with the patterns of muscle activity and output forces required to produce a movement. These experiments extend the description of the control of the direction of movement of a multiple degree-of-freedom joint into the spatial (direction) domain to a greater extent than previously achieved.

Animals↗
PubMed1989

[Development of mandibular movements associated with growth and development of stomatognathic system].

In order to clarify the development of mandibular movements associated with growth and development of the stomatognathic system, we compared the mandibular movements of children with normal occlusion at different Hellman's dental age between IIA and IIIB, during tooth tapping movements using the following 7 different kinds of frequency; ad lib.; 1 time/sec, 2 times/sec and 3 times/sec movements with reguration; 1 time/sec, 2 times/sec and 3 times/sec movements without reguration. Then, we determined the correlation between the results and the subjects' chronological age and obtained the following findings. 1) During 5 strokes between the 3rd and 7th strokes after the start of the tooth tapping movements, mandibular movements were not very diversified among 30 tooth tapping movements using the 7 different kinds of frequency, and the mean values were almost consistent. 2) In the 5 strokes between the 3rd and 7th strokes at all dental age, each determined item showed minimal dispersion during the 3 times/sec unregurated movements. 3) In the following items, changes related to age were noted during the 3 times/sec unregurated movements. (1) Cycle time decreased and became closer to the calculated value (333.33 msec), and maximum velocity in closing increased as age advanced. (2) Although there was no significant correlation with the subjects' chronological age, degree of mandibular opening, duration of opening phase, duration of closing phase, duration of occluding phase and velocity peak time in opening decreased, and maximum velocity in opening increased as age advanced. (3) Velocity peak time in closing was only slightly influenced by age. 4) These results indicate that mandibular movements develop in the course of growth and development of the stomatognathic system.

Humans↗
PubMed1988

[Fetal respiratory movements].

In the human species, foetal breathing movements are detectable from the fifteenth week of gestation and their incidence increases until the start of the third trimester. Over the last 10 weeks, breathing movements are present for 30% of the time. These are contemporaneous with body and ocular movements, suggesting an association between breathing movements and paradoxical sleep, as has been seen in the foetal lamb. These phases of activity alternate with phases of foetal immobility during which breathing movements are often absent. The incidence of foetal movements rises in the late post-prandial period, under the effect of maternal hyperglycaemia. After the establishment of regular uterine contractions, foetal breathing movements disappear, perhaps under the effect of prostaglandins E2 and/or a reduction in placental blood flow. Maternal hypercapnia leads to a rise in foetal breathing movements, which corresponds in the animal to the paradoxical sleep state. In the foetal lamb, hypoxaemia is accompanied by a cessation of breathing movements coinciding with a passage to quiet sleep. It is probable that the human foetus produces a similar reaction to hypoxaemia. During quiet sleep an inhibition of the respiratory centres would exist, disappearing during paradoxical sleep. Alcohol and certain anaesthetic agents lead to an inhibition of foetal breathing movements. The effect of tobacco remains controversial. The role of foetal breathing movements in pulmonary maturation is discussed in the human species.

Blood Glucose↗
PubMed1984

Elicitation of motion sickness by head movements in the microgravity phase of parabolic flight maneuvers.

During parabolic flight maneuvers in a Boeing KC-135 aircraft 44 college students were tested for motion sickness susceptibility. These subjects were categorized as 1) insusceptible, 2) moderately susceptible, or 3) highly susceptible to motion sickness during exposure to varying gravitoinertial force levels. After categorization, they were tested in the microgravity phase of parabolic flight to see how three types of head movements affected their baseline susceptibility. The head movements evaluated included side-to-side swivel, shoulder-to-shoulder roll, and front-up head and trunk movements; each type of head movement was used on a separate test day for eyes-open and eyes-covered conditions. Ten cycles of head movements were made in each parabola until a motion sickness endpoint, nausea, was reached or 40 parabolas had been completed. All types of head movements significantly increased susceptibility for subjects in all categories; eyes-open conditions were always more stressful than eyes-closed for each kind of head movement. These findings show unequivocally that natural head movements in microgravity can elicit symptoms of motion sickness. They suggest that head movements play an important etiological role in space motion sickness. In ground based studies where head movements are necessary to elicit symptoms, they are also necessary to elicit adaptation. We describe the use of paced and incremented head movement schedules as a possible way of partially alleviating space motion sickness.

Aerospace Medicine↗
PubMed1984

[A roentgenographic study of extension movements in osteoarthritic knees].

Serial lateral roentgenographs were taken of extension movements in 120 normal knees and 153 osteoarthritic knees, and analysis was made of both gliding and rolling movements of the medial femoral condyle with respect to the tibia. In normal knees, the medial femoral condyle showed a smooth forward shift with respect to the tibia in their extension movements from flexion 90 degrees to maximum extension, made gliding movements from flexion 90 degrees to 60 degrees, and then, added with an element of rolling movements, took its final extension position. Index of contact for flexion 90 degrees and maximum extension position was 40.94 +/- 4.87% and 54.38 +/- 6.55%, respectively, and index of shift was 14.33 +/- 4.66%, with no differences by age. In osteoarthritic knees, with the grade of disease, the alteration on the cartilaginous surface of the medial femoral condyle progressed and a rhythm disturbance occurred between gliding and rolling movements; from flexion 90 degrees to 60 degrees gliding movements were made similarly to normal knees, from flexion 60 degrees rolling movements increased, and further from flexion 30 degrees to the final extension position, rolling movements rather than gliding movements played the leading role, with observed strong forward shift of the medial femoral condyle and extension disturbance of the knee joint. Index of contact for 90 degrees and maximum extension position was 40.41 +/- 6.71% and 60.80 +/- 9.52%, respectively, and index of shift was 23.39 +/- 9.94% with an index of rearward shift of over 5% on the way to extension observed in 39 joints (25%). According to the above result, it was concluded that the aggravation of osteoarthritic knees could be partly due to abnormal gliding and rolling of the medial femoral condyle in knee extension movements.

Adult↗
PubMed1977

Fetal movements in utero: nature, assessment, prognostic value, timing of delivery.

Fetal movements in utero are an expression of fetal well-being. However, a sudden increase of fetal movements is a sign of acute fetal distress, such as in cases of cord complications or abruptio placentae. Decreased fetal movements are seen in cases of chronic fetal distress such as preeclampsia, hypertension in pregnancy, etc. It was shown that in these cases a pronounced decrease up to cessation of fetal movements occurred before fetal death in utero while fetal heart beats were still audible for at least 12 hours. This situation was called "movements alarm signal" (MAS). This sign points to a severely disturbed fetus and indicates impending intrauterine fetal death. Such a development is an indication for immediate delivery of the fetus, provided it is viable. High-risk pregnant women are instructed to assess and record fetal movements daily as a monitor of fetal condition. A special device which records fetal movements is used to confirm the women's assessment of fetal movement. It was shown that fetal movement monitoring was found to be more reliable than the urinary estriol determination in predicting impending fetal death in utero. It was also shown that in cases of MAS, fetal heart rate (FHR) changes will appear 1 to 4 days after the MAS has appeared. Meconium was found in only 50% of these cases. Increased fetal movements are manifested as a response to various stimuli such as sound, light, touch, and ultrasound. Classification of high-risk pregnancies into 3 groups according to the hormone assays, enzyme assays, ultrasonic cephalometry, fetal movements, and FHR is suggested.

Acoustic Stimulation↗
PubMed1998

Partial inactivation of the primary motor cortex hand area: effects on individuated finger movements.

After large lesions of the primary motor cortex (M1), voluntary movements of affected body parts are weak and slow. In addition, the relative independence of moving one body part without others is lost; attempts at individuated movements of a given body part are accompanied by excessive, unintended motion of contiguous body parts. The effects of partial inactivation of the M1 hand area are comparatively unknown, however. If the M1 hand area contains the somatotopically ordered finger representations implied by the classic homunculus or simiusculus, then partial inactivation might produce weakness, slowness, and loss of independence of one or two adjacent digits without affecting other digits. But if control of each finger movement is distributed in the M1 hand area as many studies suggest, then partial inactivation might produce dissociation of weakness, slowness, and relative independence of movement, and which fingers movements are impaired might be unrelated to the location of the inactivation along the central sulcus. To investigate the motoric deficits resulting from partial inactivation of the M1 hand area, we therefore made single intracortical injections of muscimol as trained monkeys performed visually cued, individuated flexion-extension movements of the fingers and wrist. We found little if any evidence that which finger movements were impaired after each injection was related to the injection location along the central sulcus. Unimpaired fingers could be flanked on both sides by impaired fingers, and the flexion movements of a given finger could be unaffected even though the extension movements were impaired, or vice versa. Partial inactivation also could produce dissociated weakness and slowness versus loss of independence in a given finger movement. These findings suggest that control of each individuated finger movement is distributed widely in the M1 hand area.

Animals↗
PubMed2000

Movement cueing and motor execution in patients with dystonia: a kinematic study.

To investigate whether the type of movement cueing influences motor performance in patients with dystonia, we studied externally triggered (ET) and self-initiated (SI) sequential rapid arm movements in patients with generalized or focal dystonia and healthy control subjects. The ET task required subjects to initiate movements in response to consecutive visual cues; the SI task allowed them to start at will. To determine whether patients found sequential motor tasks more difficult than single tasks, we also analyzed single ET movements. Control subjects performed the SI task significantly faster than the ET task. Their single ET movements and first ET sequential submovements had similar speeds. Patients with generalized dystonia were slow in performing the single movement, the ET and the SI sequential tasks, and they executed the SI sequence more slowly than the ET. They made long pauses between SI sequential submovements, had longer reaction times during the ET sequences, and performed the first ET submovement more slowly than the single ET movement. Patients with focal dystonia had normal reaction times but they performed single and sequential tasks slowly, made long pauses during SI tasks, and also executed the first ET submovement more slowly than the single ET movement. Our findings indicate that patients with dystonia have a general impairment of sequential movements. The more marked slowness in executing SI than ET movements observed in patients with generalized dystonia shows that dystonia impairs internal cueing more than external cueing mechanisms. Overall, these findings imply abnormal activation of primary and nonprimary motor areas during movement in dystonia. The greater impairment of SI tasks as well as the delayed motor responses during ET task suggest predominant underactivity of the supplementary motor area.

Adolescent↗
PubMed2001

The association between risk factors for tardive dyskinesia and phenylalanine-induced abnormal movements in schizophrenia.

We examined whether an oral challenge dose of the amino acid phenylalanine (a dopamine precursor) exacerbates the abnormal movements of tardive dyskinesia (TD). We also examined age, gender, treatment duration, and baseline movement severity in relation to phenylalanine-induced changes in movements. Lastly, we assessed the influence of fasting amino acid levels on phenylalanine-induced movements. In a placebo-controlled fashion, the abnormal involuntary movement scale (AIMS) was obtained on 25 patients before and after a phenylalanine challenge drink. A general linear model determined the relative effects of age, gender, treatment duration, and fasting amino acid levels on the magnitude of induced movements. Age and treatment duration did not affect phenylalanine-induced movements. Lower fasting levels of phenylalanine were associated with greater movements after controlling for age, F = 11.89, p < 0.003. The severity of abnormal movements at baseline also predicted response to phenylalanine, F = 8.62, p = 0.0079. Brain amino acid and neurotransmitter pools are influenced by changes in dietary protein, which may have implications in the development and prevention of movement disorders. This study suggests that fasting amino acid levels may predict differences in vulnerability to movements during an influx of neurotransmitter precursors, perhaps due to long-term compensatory changes in receptor sensitivity. Copyright 2001 John Wiley & Sons, Ltd.

Journal Article↗