May 1, 2023
Author: Manish Verma
Editor: Dr. Jitendra Kumar Sinha
Schizophrenia is a multifaceted psychiatric disorder that impairs an individual’s cognitive, affective, and behavioral functions. It arises from intricate alterations in the brain’s structure and function. Ongoing research endeavors are striving to unveil the pathophysiological underpinnings of this disorder and to develop innovative therapeutic modalities. Despite these efforts, there is still a long way to go before we can fully comprehend the intricacies of this disorder and develop effective interventions to mitigate its debilitating effects on individuals and society.
Recently, a study published in Schizophrenia Bulletin aimed to explore the possible association between fixational saccades and schizophrenia. Fixational saccades are tiny, involuntary eye movements that occur during visual fixation, and are suggested to reflect the activity of the cortical-subcortical-cerebellar circuit, which is known to be altered in schizophrenia and is linked to cognitive and behavioral impairments.
Visual fixation is a crucial and ubiquitous behavioral pattern that facilitates information acquisition and decision-making in humans. The act of visual fixation is accompanied by the occurrence of both small (microsaccades) and large (macrosaccades) saccades, which are spontaneous and frequent in nature. These fixational saccades have been found to be sensitive to the structural and functional changes in the cortical-subcortical-cerebellar circuit and have been shown to be closely associated with cognitive processes. Despite this, there is a significant dearth of research examining the performances of fixational saccades in individuals with schizophrenia.
The researchers enrolled 140 drug-naïve patients experiencing first-episode schizophrenia and 160 age-matched healthy controls. Participants were instructed to maintain their gaze on a stationary point for six seconds, while their eye movements were recorded. The findings revealed that patients with schizophrenia had abnormal fixational saccades, primarily in the vertical direction, along with longer duration, faster peak velocity, and larger amplitude saccades, especially in the horizontal direction.
Notably, the study highlighted a correlation between fixational saccade abnormalities and cognitive and positive symptoms of schizophrenia. Patients with more deviant fixational saccades had higher scores on the Positive and Negative Syndrome Scale (PANSS), a measure of symptom severity, and lower scores on the Measurement and Treatment Research to Improve Cognition in Schizophrenia Consensus Cognitive Battery (MCCB), a cognitive function test.
The study’s findings suggest that fixational saccades hold potential as a biomarker for diagnosing schizophrenia and assessing the severity of symptoms. The researchers developed a machine learning algorithm that classified patients with 85% accuracy in 60 seconds, based solely on their fixational eye movements. This implies that fixational saccades could serve as a non-invasive and objective tool for diagnosing and treating schizophrenia.
In conclusion, this study sheds light on the possible role of fixational saccades as a marker for schizophrenia. Further investigations are necessary to validate and expand upon these findings. However, the study’s results suggest that fixational saccades may offer a promising avenue for developing new biomarkers and therapies for this intricate disorder.
References:
- Liu, X., Li, Y., Xu, L., Zhang, T., Cui, H., Wei, Y., Xia, M., Su, W., Tang, Y., Tang, X., Zhang, D., Spillmann, L., Max Andolina, I., McLoughlin, N., Wang, W., & Wang, J. (2023). Spatial and Temporal Abnormalities of Spontaneous Fixational Saccades and Their Correlates With Positive and Cognitive Symptoms in Schizophrenia. Schizophrenia bulletin, sbad039. Advance online publication. https://doi.org/10.1093/schbul/sbad039
- Kantrowitz, J. T., Correll, C. U., Jain, R., & Cutler, A. J. (2023). New Developments in the Treatment of Schizophrenia: An Expert Roundtable. The international journal of neuropsychopharmacology, pyad011. Advance online publication. https://doi.org/10.1093/ijnp/pyad011
- Velligan, D. I., & Rao, S. (2023). The Epidemiology and Global Burden of Schizophrenia. The Journal of clinical psychiatry, 84(1), MS21078COM5. https://doi.org/10.4088/JCP.MS21078COM5
- Sinha, Jitendra & Sachdeva, Punya & Ahmad, Faizan & Sarkar, Jasmine & Izhar, Raafiah & Rahman, Ayesha & Ghosh, Shampa. (2023). Pharmacotherapy and Emerging Treatment Strategies for Schizophrenia. 10.1007/978-981-19-7022-1_10.
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