Publications by authors named "Miguel Schwartz"

Early diagnosis of Parkinson's disease (PD) is important because it affects the choice of therapy and is subject to a relatively high degree of error. In addition, early detection of PD can potentially enable the start of neuroprotective therapy before extensive loss of dopaminergic neurons of the substantia nigra occurs. However, until now, studies for early detection of PD using volatile biomarkers sampled only treated and medicated patients.

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Attention deficit hyperactivity disorder (ADHD) is thought to involve an executive inhibitory control (IC) deficit, yet it is not clear if this is a general deficit affecting both cold and hot EC, and if methylphenidate (MPH) affects both systems in treated children. We explored this by using a Stroop-like task in children with ADHD as compared to controls, containing different types of emotional stimuli (six levels), and we investigated the role of intervention with MPH on IC as compared to placebo. Children with ADHD and controls (N = 40; 7-13 years old) were tested with a hot and cold Stroop-like task.

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The diagnosis of Parkinson's disease (PD) is based on the identification of at least two of the cardinal motor signs of the disease: rest tremor, bradykinesia, rigidity, and in progressive state the loss of postural reflexes. The disease is manifested mainly by motor signs but several non-motor features are present in patients with PD. Often, these non-motor symptoms can precede the motor features of the disease.

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Dopaminergic neurons in the basal ganglia normally fire in a continuous manner, maintaining the striatal dopamine concentration at a relatively constant level. In Parkinson's disease, dopaminergic treatment produces a discontinuous stimulation, inducing an intermittent pulsatile activation of the striatal receptors. It is likely that the oscillations in the dopamine level in the striatum contribute to the development of motor complications.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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