Thiago Monteiro de Paiva Fernandes

Comparison of color discrimination in chronic heavy smokers and healthy subjects

Background: Cigarette smoke is probably the most significant source of exposure to toxic chemicals for humans, involving health-damaging components, such as nicotine, hydrogen cyanide and formaldehyde. The aim of the present study was to assess the influence of chronic heavy smoking on color discrimination (CD). Methods: All subjects were free of any neuropsychiatric disorder, identifiable ocular disease and had normal acuity. No abnormalities were detected in the fundoscopic examination and in the optical coherence tomography exam. We assessed color vision for healthy heavy smokers ( n = 15; age range, 20-45 years), deprived smokers ( n = 15, age range 20-45 years) and healthy non-smokers ( n = 15; age range, 20-45 years), using the psychophysical forced-choice method. All groups were matched for gender and education level. In this paradigm, the volunteers had to choose the pseudoisochromatic stimulus containing a test frequency at four directions (e.g., up, down, right and left) in the subtest of Cambridge Colour Test (CCT): Trivector. Results: Performance on CCT differed between groups, and the observed pattern was that smokers had lower discrimination compared to non-smokers. In addition, deprived smokers presented lower discrimination to smokers and non-smokers. Contrary to expectation, the largest differences were observed for medium and long wavelengths. Conclusions: These results suggests that cigarette smoke and chronic exposure to nicotine, or withdrawal from nicotine, affects CD. This highlights the importance of understanding the diffuse effects of nicotine either attentional bias on color vision.

Effects of smoking and smoking abstinence on spatial vision in chronic heavy smokers

Cigarette smoke is a complex chemical mixture, involving health-damaging components such as carbon monoxide, ammonia, pyridine, toluene and nicotine. While cognitive functions have been well documented in heavy smokers, spatial vision has been less characterized. In the article, we investigated smoking effects through contrast sensitivity function (CSF), a rigorous procedure that measures the spatial vision. Data were recorded from 48 participants, a group of non-smokers (n = 16), a group of chronic and heavy cigarette smokers (n = 16) and deprived smokers (n = 16); age range 20–45 years. Sinewave gratings with spatial frequencies ranging from 0.25 to 20 cycles per degree were used. All subjects were free from any neurological disorder, identifiable ocular disease and had normal acuity. No abnormalities were detected in the fundoscopic examination and in the optical coherence tomography exam. Contrary to expectations, performance on CSF differed between groups. Both smokers and deprived smokers presented a loss of contrast sensitivity compared to non-smokers. Post-hoc analyses suggest that deprived smokers were less sensitive at all spatial frequencies. These results suggest that not only chronic exposure to cigarette compounds but also withdrawal from nicotine affected spatial vision. This highlights the importance of understanding diffuse effects of smoking compounds on visual spatial processing.

Colour discrimination thresholds in type 1 Bipolar Disorder: a pilot study

Although some studies have reported perceptual changes in psychosis, no definitive conclusions have been drawn about visual disturbances that are related to bipolar disorder (BPD). The purpose of the present study was to evaluate colour vision in BPD patients. Data were recorded from 24 participants: healthy control group (n = 12) and type 1 BPD group (n = 12). The participants were 20–45 years old and they were free from neurological disorders and identifiable ocular disease and had normal or corrected-to-normal visual acuity. Colour discrimination was evaluated using the Lanthony D-15d, Trivector and Ellipse tests, using a psychophysical forced-choice method. The relationship of visual measures to mood state and cognitive function was also investigated. The results showed that BPD patients had higher colour discrimination thresholds in the D15d (p < 0.001), Trivector (p < 0.001) and Ellipse (p < 0.01) tests compared with healthy controls. Linear regression analysis showed that mood state was related to colour discrimination. BPD individuals were not impaired in cognitive tasks. The present study provided new evidence of potential links between type 1 BPD and visual processing impairments. This research suggests a new direction for studies and the need for research in this field of study.

Visual function alterations in epilepsy secondary to migraine with aura: A case report.

A 28-year-old White Brazilian female diagnosed with attention-deficit hyperactivity disorder began to experience severe headaches with photosensitivity. After misdiagnosis and inconclusive tests, the exams indicated the presence of idiopathic epilepsy secondary to migraine with aura. Because of the photosensitivity presented during the seizures, our purpose is to report impairments in visual processing after the patient became seizure free. Evaluation of the visual function was performed, including the analysis of contrast sensitivity and color discrimination. The results showed reduction in visual processing. A significant reduction in the contrast sensitivity function and color discrimination was observed for both eyes, with the left eye being more affected than the right eye. Results confirm that there was significant visual impairment compared with the normal pattern for both eyes. Even knowing that this is a rare case, our intent is to open new avenues for research involving photosensitive epilepsy in migraine with aura.

Tobacco Use Decreases Visual Sensitivity in Schizophrenia

Smoking prevalence in patients who are diagnosed with schizophrenia (SCZ) is higher than in the general population. Chronic tobacco use in SCZ patients may reduce the side effects of antipsychotic drugs, thus serving as a self-medication for such side effects. Understanding the ways in which chronic tobacco use influences visual sensitivity has clinical implications, which may serve as a tool for non-invasively diagnosing early-stage visual processing deficits. The present study evaluated the effects of chronic tobacco use on visual sensitivity in SCZ patients. Our purpose was to provide new directions for future research, mainly psychophysical and electrophysiological studies. In the present study, 40 smoker controls (SC), 20 SCZ tobacco users, and 20 SCZ tobacco nonusers were recruited from the Psychosocial Care Center. Visual sensitivity was compared between both SCZ groups and the SC group. Patients with SCZ who were chronic tobacco users presented lower visual sensitivity for chromatic (p < 0.001) and achromatic (p < 0.001) stimuli compared with the other groups. Our findings highlight the need to evaluate possible addictive behavior in patients with SCZ, which may contribute to public policies that seek to improve the quality of life of SCZ patients and their families.

Color vision impairments in schizophrenia and the role of antipsychotic medication type

Schizophrenia patients (SCZ) demonstrate deficits in many domains of mental functioning, including visual perception. An issue that has been relatively unexplored, in terms of explaining variation in visual function in SCZ, however, is medication use. The present study explored potential medication effects on color vision in SCZ, a process that is strongly linked to dopaminergic function in the retina. SCZ patients who had clear-cut either typical (n = 29) or atypical (n = 29) monotherapy, without any other concurrent medication, and a group of age- and gender-matched healthy controls participated in the study. Color vision was assessed by the Cambridge Colour Test, using the Trivector and Ellipse subtests. The results demonstrated impaired color perception in patients with schizophrenia, especially in those receiving typical antipsychotics, but these deficits were subtle and not generalized to all parameters. Our findings are consistent with the known neurophysiology of the retina and visual pathways, and with the effects of dopamine blocking medications, but the results should be carefully interpreted.

Tobacco use and lower accuracy in a novel facial detection task.

The aim of the present study was to investigate the ways in which tobacco addiction affects a person’s ability to recognize facial patterns. Facial detection was assessed in 16 individuals with tobacco use disorder and 16 healthy nonsmokers. Facial stimuli were taken from the Ignatian Educational Foundation (FEI) database, from which 12 male and 12 female faces were randomly selected. In the facial detection task, the subjects’ task was to detect the location of a face when it was presented with a face/nonface pair on the screen. The order of stimulus presentation was randomized within sessions. Bayesian adaptive estimation was used for stimulus presentation. Presentation times varied between 16.7 and 3,006 ms. Lower response accuracy was associated with worse discrimination. No predictive effects of the cognitive tests on facial detection were found. A person’s ability of facial detection can be applied to provide initial descriptions of impairments in the visual processing system. Early stage visual processing is impaired by chronic smoking, and subjects are able to recognize this. Therefore, there is a possibility of reversing this effect and promoting a better prognosis. The present task has biopsychosocial applications and may improve smokers’ health by detecting subtle initial changes in visual processing.

Spatial vision loss in bipolar disorder: Case series and literature review.

Several studies have investigated cognition in bipolar disorder (BPD), but there is a large gap in the literature with regard to visual processing in BPD. The contrast sensitivity function (CSF) is one of the main measures that is used to verify and describe spatial processing responses and their mechanisms. The present article describes a retrospective case series and literature review of the presentation and outcome of visual processing in BPD. Our series included 5 patients with Type I BPD, 22- to 41-years-old. None of the patients had a history of neurological or cardiovascular disease, head trauma, chronic contact with such substances as organic solvents, or current or prior drug abuse. They also did not present comorbidities. None of the patients had ocular disease, based on fundoscopic and optical coherence tomography examinations. Patients with BPD had lower CSF at low and high spatial frequencies when compared with a nonclinic group. Further control studies are needed to confirm or refute the assumption that BPD affects visual processing.

Cognition-enhancing effect of vagus nerve stimulation on refractory epilepsy secondary to lissencephaly: A case report.

A 19-year-old White Brazilian female with epilepsy was evaluated after failing to become seizure free even with the use of antiepileptic drugs. Due to difficulty of communication, a neurocognitive assessment indicated the presence of attenuated delayed psychomotor and cognitive development. In addition to refractory epilepsy, with 30 seizures/day, a clinical diagnosis of lissencephaly was confirmed after MRI and electroencephalography monitoring. The intervention for reducing the seizures consisted of vagus nerve stimulation (VNS). After 30 days, relatives reported significant cognitive and behavioral improvement, such as reduced aggression and impulsivity, which lasted 60 and 90 days (follow-up). Furthermore, there was an improvement in psychomotor and self-care capacity. At this time, there was a significant reduction in seizures from about 30 seizures/month to 5 seizures/month. This case highlights the significant cognitive improvement even before the reduction of seizures in a patient with intractable drug-resistant epilepsy after VNS implant. Even though this is a rare case, the use of VNS in lissencephaly may be a potential tool for cognitive and behavioral improvement.

Psychophysical evaluation of contrast sensitivity using Gabor patches in tobacco addiction

This study, an extension of Fernandes et al. (2017), provided consistent contrast sensitivity function (CSF) measurements in a large sample. CSF was assessed for luminance stimuli in different 48 chronic smokers and 50 healthy nonsmokers. Stimuli for the CSF were Gabor patches with spatial frequencies of .2, 2.5, 5.0, 10.0, and 20.0 cycles per degree (cpd). The use of Gabor patches minimizes uncertainty in spatial position and detection of frequencies. The Gabor patches consisted of vertical gratings that were multiplied by a two-dimensional spatial Gaussian envelope. All of the groups were matched for gender and level of education. All of the participants were free from any neurological disorder, cardiovascular disease, and identifiable ocular disease, and they had normal or corrected-to-normal visual acuity. No abnormalities were detected on the fundoscopic examination or optical coherence tomographic examination. The smoker group had a lower CSF compared with healthy nonsmokers at all spatial frequencies. These results indicate that cigarette smoking or chronic exposure to its constituent compounds affects early-stage visual discrimination, suggesting the existence of deficits in early visual spatial processing in smokers.