Road vehicle collision suicide in Australia: Trends, collision types, and individual characteristics.

BACKGROUND: Suicide by road vehicle collision in Australia is under-explored with mixed findings. We aimed to address this research gap by examining time trends, different types of vehicle collision, and individual characteristics related to vehicle-collision suicide. METHOD: We retrospectively analyzed deaths by suicide between 1st January 2001 and 31st December 2017 in Australia, using coronial records from the National Coronial Information System. The travel mode used and collision counterpart were retrieved from records of death by vehicle-collision suicide using all available information. We conducted negative binomial regression analysis to examine annual changes in suicide rate by vehicle collision on a public road (N = 640) and other methods of suicide (N = 41,890), and logistic regression analysis to examine individual characteristics associated with the likelihood of dying by suicide via road vehicle collision. RESULTS: Overall, the national suicide rate involving road vehicle collision significantly increased, while the rate by other methods significantly decreased. Drivers accounted for 61% of suicide events by vehicle collision, of which 72% were single-vehicle collisions (commonly involving a tree). For multiple-vehicle collision suicide events, 82% involved collision with a truck. Pedestrians accounted for more than one-third of suicide events, of which 58% involved collision with a truck and 23% involved collision with a car/van. Individuals who were male (odds ratio 1.15; 95% CI 0.88-1.50), aged <25 years old (odds ratio 5.27; 95% CI 3.05-9.10), non-Indigenous (odds ratio 3.36; 95% CI 1.71-6.62), and born overseas (odds ratio 1.40; 95% CI 1.10-1.79) were more likely to die by vehicle-collision suicide than by other methods of suicide. CONCLUSIONS: This study provides a better understanding of road vehicle collision suicide in Australia and informs future research directions on topic. Our findings can be used to inform suicide prevention initiatives to reduce vehicle-collision suicide deaths.

Widening socioeconomic inequalities in Australian suicide, despite recent declines in suicide rates.

PURPOSE: This study aims to investigate trends in socioeconomic inequalities of suicide from 1979 to 2013 for Australian males and females aged 15-34 years and 35-64 years. METHODS: Data on suicides and population were obtained from national registries. An area-based measure of socioeconomic status (SES) was used, and categorized into low, middle, and high SES areas. Suicide rates for each SES groups were estimated using a negative binomial regression model, adjusted for confounders. Socioeconomic inequalities in suicide were assessed using absolute and relative risk of low-to-high SES areas. Secular changes in socioeconomic inequalities were assessed using trend tests for relative risk. RESULTS: For young males, there was an increase in socioeconomic inequality driven by a significant decrease in suicide rates in high SES areas. For older males, inequality in suicide increased by 29%, which was related to a marked increase in suicide rates in low SES areas. Inequalities in both young and older female suicides also increased. These increases occurred when corresponding suicide rates in high SES areas decreased. CONCLUSIONS: Recent widening socioeconomic inequalities in Australian suicide have been primarily associated with declines in suicide rates in high SES areas. However, an increasing inequality in older male suicide is linked with low SES. Efforts targeting people from poor areas, especially older males, should be considered when developing suicide prevention strategy.

The effect of stimulus strength on binocular rivalry rate in healthy individuals: Implications for genetic, clinical and individual differences studies.

Binocular rivalry (BR) occurs when conflicting images concurrently presented to corresponding retinal locations of each eye stochastically alternate in perception. Anomalies of BR rate have been examined in a range of clinical psychiatric conditions. In particular, slow BR rate has been proposed as an endophenotype for bipolar disorder (BD) to improve power in large-scale genome-wide association studies. Examining the validity of BR rate as a BD endophenotype however requires large-scale datasets (n=1000s to 10,000s), a standardized testing protocol, and optimization of stimulus parameters to maximize separation between BD and healthy groups. Such requirements are indeed relevant to all clinical psychiatric BR studies. Here we address the issue of stimulus optimization by examining the effect of stimulus parameter variation on BR rate and mixed-percept duration (MPD) in healthy individuals. We aimed to identify the stimulus parameters that induced the fastest BR rates with the least MPD. Employing a repeated-measures within-subjects design, 40 healthy adults completed four BR tasks using orthogonally drifting grating stimuli that varied in drift speed and aperture size. Pairwise comparisons were performed to determine modulation of BR rate and MPD by these stimulus parameters, and individual variation of such modulation was also assessed. From amongst the stimulus parameters examined, we found that 8cycles/s drift speed in a 1.5° aperture induced the fastest BR rate without increasing MPD, but that BR rate with this stimulus configuration was not substantially different to BR rate with stimulus parameters we have used in previous studies (i.e., 4cycles/s drift speed in a 1.5° aperture). In addition to contributing to stimulus optimization issues, the findings have implications for Levelt's Proposition IV of binocular rivalry dynamics and individual differences in such dynamics.

No Relationship Between Binocular Rivalry Rate and Eye-Movement Profiles in Healthy Individuals: A Bayes Factor Analysis.

Binocular rivalry (BR) is an intriguing phenomenon in which conflicting images are presented, one to each eye, resulting in perceptual alternations between each image. The rate of BR has been proposed as a potential endophenotype for bipolar disorder because (a) it is well established that this highly heritable psychiatric condition is associated with slower BR rate than in controls, and (b) an individual's BR rate is approximately 50% genetically determined. However, eye movements (EMs) could potentially account for the slow BR trait given EM anomalies are observed in psychiatric populations, and there has been report of an association between saccadic rate and BR rate in healthy individuals. Here, we sought to assess the relationship between BR rate and EMs in healthy individuals (N = 40, mean age = 34.4) using separate BR and EM tasks, with the latter measuring saccades during anticipatory, antisaccade, prosaccade, self-paced, free-viewing, and smooth-pursuit tasks. No correlation was found between BR rate and any EM measure for any BR task (p > .01) with substantial evidence favoring this lack of association (BF(01) > 3). This finding is in contrast to previous data and has important implications for using BR rate as an endophenotype. If replicated in clinical psychiatric populations, EM interpretations of the slow BR trait can be excluded.

Dichoptic viewing methods for binocular rivalry research: prospects for large-scale clinical and genetic studies.

Binocular rivalry (BR) is an intriguing phenomenon that occurs when two different images are presented, one to each eye, resulting in alternation or rivalry between the percepts. The phenomenon has been studied for nearly 200 years, with renewed and intensive investigation over recent decades. The rate of perceptual switching has long been known to vary widely between individuals but to be relatively stable within individuals. A recent twin study demonstrated that individual variation in BR rate is under substantial genetic control, a finding that also represented the first report, using a large study, of genetic contribution for any post-retinal visual processing phenomenon. The twin study had been prompted by earlier work showing BR rate was slow in the heritable psychiatric condition, bipolar disorder (BD). Together, these studies suggested that slow BR may represent an endophenotype for BD, and heralded the advent of modern clinical and genetic studies of rivalry. This new focus has coincided with rapid advances in 3D display technology, but despite such progress, specific development of technology for rivalry research has been lacking. This review therefore compares different display methods for BR research across several factors, including viewing parameters, image quality, equipment cost, compatibility with other investigative methods, subject group, and sample size, with a focus on requirements specific to large-scale clinical and genetic studies. It is intended to be a resource for investigators new to BR research, such as clinicians and geneticists, and to stimulate the development of 3D display technology for advancing interdisciplinary studies of rivalry.