Cross-Cutting Advancements Usher in a New Era for Motor Research in Psychosis

Abstract

As gesture serves as an interaction point between motor, language, and sensory-integration processes, an intersection also implicated in psychosis, schizophrenia researchers have recently turned toward this area as well. 1 The findings of Walther et al 2 move our understanding of this nascent field significantly ahead, with results indicating that deficits in gesture performance and perception are closely tied with clinical and functional outcome in individuals with schizophrenia over a 6-month period. More broadly, this article suggests that a test of hand gesture may provide a viable method for predicting clinical course and potentially highlighting a novel vulnerability subtype in schizophrenia patients. Given the importance of these findings, and the relative ease of such assessments, the questions remain-why are we not seeing more studies like this, and where are the translational applications? Further, in addition to aberrant gesture, schizophrenia has been linked with a range of motor signs including delays in developmental milestones, clumsiness, poor coordination, abnormalities in gait, posture and neuromusculature, diffuse neurological soft signs, catatonia, psychomotor slowing, and both medication-induced and spontaneous hyper/hypo dyskinesias spanning muscle groups throughout the body. Despite the broad array of affected behaviors and characteristics, and the long history of movement and motor research in this area, 3 the question remains, why is this such a neglected area in our field?There are several factors that have been impeding more widespread use of motor variables in cuttingedge research. First, rigid intradisciplinary boundaries between neurology and psychiatry have historically kept abnormalities in movement and socio-emotional behavior distinct. In a related issue, until recently, key relevant target structures such as the basal ganglia and cerebellum have been viewed primarily as a motor centers and related movement behaviors have not been linked into the sophisticated comprehensive models or etiological theories that are often necessary generate enthusiasm about a domain or target. Second, the advent of first-generation antipsychotic medications, which produce characteristic movement disorders in some patients, contributed to further confusion about etiology of movement signs. More broadly, both generations of neuroleptics have also continued to serve as a tricky barrier for definitive research in this area. 4 Third, empirical studies have relied almost entirely on drug-induced motor abnormality assessments, 5 or scales designed to follow diffuse markers (eg, neurological soft signs). 6 While these instruments can be reliable at a particular site, they require highly specialized training, miss more subtle movements, and can press investigators to impose subjective categories on continuous phenotypes. Fourth, although it has been clear for some time that there are motor abnormalities present in psychosis, the translational relevance of these markers is uncertain. Finally, motor behaviors...

Objective and quantitative equilibriometric evaluation of individual locomotor behaviour in schizophrenia: Translational and clinical implications

“…With relatively few exceptions (limited to the most disorganized and severely psychotic or negativistic cases), the majority of patients follow the instructions and cooperate adequately during the test. Nowadays, it is already confirmed that the objectively evaluated neuromotor and psychomotor disturbances reflect the brain dysfunctions in schizophrenia more reliably than the subjective symptoms . Our research data provide further evidence that the treatment decisions for the individual schizophrenic patients are more correct if they are guided by the objectively measured LMPs .…”

“…Such an objective and quantitative evaluation at a single‐patient level is in line with the modern tendency for personalized and precision medicine in the psychiatric neuroscience research, aimed at replacing the traditional categorical diagnostic approach with a more dimensional one that looks for “theranostic” rather than for diagnostic biomarkers . It is interesting to note that just in the last few years the motor dimension was proposed to be included in the translational psychiatric neuroscience research . It is noteworthy that instrumental motor measures are capable of detecting subthreshold movement abnormalities that are not detectable to the eye.…”

“…Despite their objective character, however, in the everyday clinical practice, these motor disturbances are still recorded and evaluated subjectively, by clinical observation and description. Just in the recent years, a few motion analysis laboratories began to evaluate them by objective instrumental methods . Hence, it is reasonable to presume that (in the absence of clinically manifested neurological symptoms) the abnormal LMPs in the majority of schizophrenic patients reflect psychomotor disturbances .…”

“…As mentioned before, every single schizophrenic patient might combine prototypical schizotaxic LMPs (indicating locomotor ataxia) with atypical nonschizotaxic ones (indicating either hypolocomotion or hyperlocomotion). Evaluating such subclinical combinations of qualitative and quantitative locomotor abnormalities could allow us to make more reliable predictions for more appropriate drug therapy and its more accurate dosage, which might lead to individualized or personalized treatment strategies . On the other hand, the diversity of possible locomotor combinations could explain why the individual reactions to one and the same antipsychotic treatment might vary from patient to patient and why these individual reactions are more predictable by objective evaluation of the patient's motor abnormalities .…”

Research domain criteria (RDoC) grows up: Strengthening neurodevelopment investigation within the RDoC framework

“…As not all individuals in a high-risk group do go on to develop a psychotic disorder, this is highly relevant (Mittal & Walker, 2011). Irrespective of medication (i.e., the motor abnormalities are present in neuroleptic naïve samples), these spontaneous jerking movements in the head, face, lips, and torso can continue to emerge during the adolescent prodromal period, until onset, when they remain a key clinical feature of the illness (Pappa and Dazzan, 2009; Mittal, 2016; Kendler, 2016). At least one cross-sectional study suggests that with advanced age, all patients with schizophrenia will eventually develop these behaviors (Quinn et al, 2001).…”