Combined influence of illness duration and medication type on visual sensitivity in schizophrenia

Abstract

Objective: Patients with schizophrenia have visual processing impairments. The main findings from the literature indicate that these deficits may be related to differences in paradigms, medications, and illness duration. This study is part of a large-scale study investigating visual sensitivity in schizophrenia. Here we aimed to investigate the combined effects of illness duration and antipsychotic use on contrast sensitivity function. Methods: Data were collected from 50 healthy controls and 50 outpatients with schizophrenia (classified according to illness duration and medication type) aged 20-45 years old. The contrast sensitivity function was measured for spatial frequencies ranging from 0.2 to 20 cycles per degree using linear sine-wave gratings. Results: Patients with an illness duration 4 5 years had more pronounced deficits. Differences in the combined effects of illness duration and antipsychotic use were marked in patients on typical antipsychotics who had been ill 4 10 years. No significant differences were found between typical and atypical antipsychotics in patients with an illness duration o 5 years. Conclusion: Visual impairment was related to both long illness duration and medication type. These results should be tested in further studies to investigate pharmacological mechanisms.

Longer illness duration is associated with greater individual variability in functional brain activity in Schizophrenia, but not bipolar disorder

“…The frontal lobes in particular have been shown to be vulnerable to the progressive effects of schizophrenia-related morbidity ( Molina et al, 2004 , Premkumar et al, 2006 ), with regional dysconnectivity ( Woodruff et al, 1997 ) as well as a decline in structural integrity and function as illness persists ( Elsabagh et al, 2009 , Premkumar et al, 2008 ). Consistently, illness duration is a significant predictor of cognitive deficits ( Irani et al, 2011 ), with deterioration in cognitive abilities over the course of illness ( Altamura et al, 2015 , Almeida et al, 2019 , Wood et al, 2002 , Mathes et al, 2005 ). Our findings suggest illness duration-related changes in brain function that may lead to greater variability in patterns of brain activity.…”

“…As such, illness duration is considered an estimate, where the time span from disorder onset to proper diagnosis cannot be accounted for. Additionally, as detailed medical history was not available, conclusions that can be drawn from this study are limited by potential effects of medication ( Almeida et al, 2019 ) or other secondary effects such as sedentary lifestyle, social isolation, etc. that may play an important moderating role.…”

“…It should be acknowledged that this reflects an estimate of illness duration, as prodromal stages and potential delays in diagnosis cannot be fully accounted for. Furthermore, different medications can have a moderating effect on illness-related biological processes ( Almeida et al, 2019 ), and progressive changes in brain function may be related to the use of antipsychotic medication ( Lesh et al, 2015 ) as well as the duration of untreated illness ( Sarpal et al, 2017 ). As such, chronological considerations of illness duration cannot be fully separated from such processes, or other external social/personal factors (i.e., contact with clinical services and illness chronicity ( Premkumar et al, 2008 ); potential changes in variability over time can be regarded as being related to a range of chronicity related determinants.…”

“…Illness duration is defined as the time after the onset of a psychiatric disorder ( Breitborde et al, 2009 ). Understanding the neurobiological effects of illness duration has clinical implications, given its robust associations with poorer real-world outcomes and significant role in predicting cognitive performance ( Altamura et al, 2015 , Almeida et al, 2019 , Bowie et al, 2014 ). However, despite the influence of illness duration on patients’ functioning, this variable is often neglected in studies and rarely alluded to as a potential confounding factor ( Altamura et al, 2015 , Altamura et al, 2011 ).…”