The paper of Walther and Mittal contains important new insights of motor behavior in psychosis and other severe mental illness (SMI) research. They discuss the role of motor abnormalities, eg, dyskinesia, parkinsonism, bradykinesia, motor coordination problems, neurological soft signs, stereotypies, hand gesture defects, and catatonia, as transdiagnostic markers directly linked to psychopathology in psychosis and other SMI. That motor abnormalities were inherent in psychotic disorders had been known for more than a hundred years and several meta-analyses confirm an increased risk of dyskinesia, parkinsonism, and neurological soft signs in antipsychotic-naive patients with schizophrenia compared to healthy controls.1,2 Over the years, several systematic reviews have demonstrated the clinical relevance of motor abnormalities, as they have been related to psychotic symptoms, negative symptoms, and cognitive deficits in psychosis.2,3 For clinical practice, the most important question is the diagnostic and treatment value of motor abnormalities in psychosis. Thus, elucidating the relation between motor behavior and the psychotic illness course is highly relevant for prediction and intervention. A recent systematic review showed that movement abnormalities have a prognostic value for clinical and functional outcome in psychosis. The review (68 studies, total of 23 630 subjects) showed that increased levels of movement abnormalities (in particular neurological soft signs, parkinsonism, and dyskinesia) were related to deteriorating symptomatic and poor functional outcome over time. This was found by individuals at clinical high risk for psychosis, patients with first-episode psychosis, and patients with chronic schizophrenia.4 Thus, motor abnormalities have prognostic value in psychotic disorders, justifying the important clinical questions in the Walther and Mittal paper, namely who will develop mental disorders among high-risk clinical patients, who will have favorable outcomes in the face of an existing mental disorder, and who benefits most from specific treatments?