The basic role of cerebellar dysfunctions in schizophrenia pathophysiology is already well-known. Importantly, cerebellar signs such as gait and balance coordination deficits are objectively manifested and measurable. However, both early detection and treatment monitoring of the illness are still-based mainly on subjective psychopathological symptoms.

To introduce an objective and quantitative approach to the cerebellar gait and balance disorders in schizophrenia.

An original (internationally patented) method for objective equilibriometric quantification of stepping locomotion (a kind of motion analysis system) was developed and then applied repetitively in 230 schizophrenic patients and 230 well-matched healthy controls.

Subclinical but objectively measurable equilibriometric locomotor ataxia (ELA) was identified in a large proportion of the investigated patients. Its severity fluctuated along with the changes in the clinical state. As a rule, the degree of ELA transiently increases during psychotic exacerbation and gradually returns to its prepsychotic level during therapeutic remission. Data analysis revealed that the basic (prepsychotic and postpsychotic) ELA could be viewed as a new schizotaxic biomarker (trait-marker) for schizophrenia, while the degree of its severity could serve as a new objectively measurable state-marker for psychosis. Besides, its dynamics during antipsychotic treatment might be used as an objective measure of the therapeutic response (a kind of surrogate pharmacodynamic biomarker).

Objective quantification of the ELA allows for early detection of subclinical signs of cerebellar ataxia (or schizotaxia) in individuals at high-risk for schizophrenia, whereas in psychotic patients it permits their objective antipsychotic-treatment monitoring.

The authors have not supplied their declaration of competing interest.