Eye-movements during number comparison: Associations to sex and sex hormones

Eye-Movements During Navigation in a Virtual Environment: Sex Differences and Relationship to Sex Hormones

Sex differences in spatial navigation have been related to different navigation strategies. For example, women are more likely to utilize local landmark-information in the environment compared to men. Furthermore, sex differences appear to be more pronounced when distances need to be judged in Euclidian terms and an allocentric representation of the environment is necessary. This suggests differential attentional processes during spatial navigation in men and women. However, eye-tracking studies on spatial navigation exploring these attentional processes are rare. The present study (39 men and 36 women) set out to investigate sex differences in eye-movements during spatial navigation in a 3D environment using virtual reality goggles. While we observed the expected sex differences in overall navigation performance, women did not benefit from the landmark-based instructions. Gaze fixations were in accordance with the preferred Euclidian strategy in men, but did not confirm the expected landmark-based strategy in women. However, high estradiol levels where related to an increased focus on landmark information. Surprisingly, women showed longer gaze distances than men, although the utilization of distal landmarks has been related to allocentric representations preferred by men. In fact, larger gaze distances related to slower navigation, even though previous studies suggest that the utilization of distal landmarks is beneficial for navigation. The findings are discussed with respect to the utility of virtual reality presentation for studies on sex differences in navigation. While virtual reality allows a full first-person immersion in the environment, proprioceptive and vestibular information is lacking.

The clinical phenomenology and correlations of oculogyric tics

BACKGROUND

Oculogyric tics are identified in a substantial proportion of patients with Tourette syndrome (TS) and related tic-disorders. Nevertheless, studies assessing its frequency and clinical correlations are lacking.

MATERIALS AND METHODS

We reviewed video-recordings and clinical history of 201 patients with TS and chronic motor/phonic tic disorder, diagnosed according to DSM-5.

RESULTS

Oculogyric tics presented in 22.4% of our patients. Transient upward gaze was the most common phenomenology in patients with simple oculogyric tics; whereas eye-closure followed by upward and lateral deviations was the most commonly observed phenomenon in patients with combined oculogyric tics. Oculogyric tics have a median duration of 799 ms (range 299-34,500 ms). Patients with oculogyric tics were younger (P = 0.023) and had a higher frequency of cranial tics (P = 0.037) compared to those without oculogyric tics. No differences in tic severity, frequency of attention-deficit/hyperactivity disorder, obsessive-compulsive disorder or use of dopamine receptor antagonists were observed in patients with and without oculogyric tics.

CONCLUSIONS

Oculogyric tics are a common phenomenology in chronic tic disorders. They are more common in younger patients with TS and are markers of other cranial tics, but not of TS severity or comorbid neuropsychiatric syndromes.

Sex differences in patients with Tourette syndrome

BACKGROUND

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by the presence of motor and phonic tics. It is at least three times more common in males compared with females; however, the clinical phenomenology between sexes has not been fully examined. We aimed to contrast the clinical features between males and females with TS and chronic tic disorder.

METHODS

We studied 201 consecutive patients fulfilling the diagnostic criteria for TS, persistent (or chronic) motor and vocal tic disorder and provisional tic disorder that were considered within the TS spectrum disorder. We performed blinded evaluations of video-recordings and retrospectively reviewed the clinical charts of all patients.

RESULTS

Age ranges between 4 and 65 years. Males represented 77.6% of patients in the cohort. Overall, no differences were observed in the frequency, distribution and complexity of tics between sexes, except for a higher frequency of attention-deficit/hyperactivity disorder (ADHD) (P = .003) among males. Patients younger than 18-years old, in addition to a higher frequency of ADHD (P = .026), males had a statistically higher frequency of complex motor tics (P = .049) and earlier age at onset (P = .072) than females in the multivariate regression analysis. However, these differences were lost in patients older than 18 years, due to increased complexity of tics in females with aging.

CONCLUSIONS

A sexual dimorphism was observed between patients with TS mainly before age of 18 years, suggesting an earlier onset of some types of tics and ADHD in males compared to females.