Aerial and Terrestrial Patterns: A Novel Approach to Analyzing Human Running.

Biomechanical parameters are often analyzed independently, although running gait is a dynamic system wherein changes in one parameter are likely to affect another. Accordingly, the Volodalen® method provides a model for classifying running patterns into 2 categories, aerial and terrestrial, using a global subjective rating scoring system. We aimed to validate the Volodalen® method by verifying whether the aerial and terrestrial patterns, defined subjectively by a running coach, were associated with distinct objectively-measured biomechanical parameters. The running patterns of 91 individuals were assessed subjectively using the Volodalen® method by an expert running coach during a 10-min running warm-up. Biomechanical parameters were measured objectively using the OptojumpNext® during a 50-m run performed at 3.3, 4.2, and 5 m·s(-1) and were compared between aerial- and terrestrial-classified subjects. Longer contact times and greater leg compression were observed in the terrestrial compared to the aerial runners. The aerial runners exhibited longer flight time, greater center of mass displacement, maximum vertical force and leg stiffness than the terrestrial ones. The subjective categorization of running patterns was associated with distinct objectively-quantified biomechanical parameters. Our results suggest that a subjective holistic assessment of running patterns provides insight into the biomechanics of running gaits of individuals.

[Everyday stress, routines and bipolar spectrum]. / Stress quotidien, routines et spectre bipolaire.

BACKGROUND: Bipolar patients relapse more frequently under conditions of stress, even when compliant with prescribed medication. Although the biological bases of stress reactivity remain widely debated, the disruption of biological or circadian rhythms has been suggested as one possible mechanism through which stress increases the risk of episodes. This hypothesis has gained support from recent evidence demonstrating that the disruption of social rhythms is particularly implicated in the onset of manic episodes. However, it is currently unknown to what extent bipolar patients may differ from normal controls in terms of the basic prevalence and nature of daily life routines, or if such individuals are more sensitive to the disruption of such rhythms following exposure to stress. METHOD: Using a dimensional perspective of bipolar disorder, 1728 French university students were first screened concerning diverse psychological and clinical characteristics. Two hundred and twelve individuals at high or low-risk for mood and substance use disorders were then invited to participate in a week-long period of ambulatory monitoring using the experience sampling method (ESM). During this phase, participants were given a preprogrammed PDA microcomputer which provided ambulatory assessments of behaviour and stress at fixed intervals (randomized across participants). At the end of the ESM phase, the microcomputers were collected and structured diagnostic interviews were administered to each participant. For the purposes of the current study, analyses focused on a subsample of 92 individuals, reflecting the 28 participants who met lifetime criteria for a manic (n=15) or hypomanic episode (n=13), and the 64 individuals who were free of any lifetime disorder. Data were analyzed using hierarchical nonlinear (Bernoulli) models for repeated measures. Covariates included age, sex, frequency of substance use and cognitive vulnerabilities assessed at screening. A Bonferroni correction was applied to adjust alpha levels within each category of activity, social interaction or environmental context. RESULTS: A total of 2777 valid ESM assessments were provided by the final sample concerning their behaviour and activities across diverse daily life contexts. Individuals having a lifetime history of mania or hypomania were significantly less likely than normal controls to have daily life routines relative to being at work, in class, having social contact with work colleagues or students, and to be performing personal hygiene activities. However, such individuals were more likely to be in the company of a romantic partner at the same moment each day. Time-lagged analyses demonstrated that, following conditions perceived as stressful, individuals with a history of mania or hypomania were less likely to repeat the same activities or behaviour of previous days concerning being at parents' or family's house, being at friends, and travelling or commuting, but more likely to be in a work environment, and in a bar or restaurant. CONCLUSIONS: The findings provide support for the notion of differences in daily life rhythms and routines among individuals with bipolar spectrum conditions, as well as the possibility of increased stress vulnerability in this population. Although a conservative analytic strategy was employed to minimize chance associations, the present findings can be considered only as preliminary and should be interpreted with caution in light of the moderate sample size, young age and non treatment-seeking nature of the sample. Future controlled investigations using ambulatory monitoring techniques are needed to pursue the investigation of these questions in treated samples.

Effects of cannabis and psychosis vulnerability in daily life: an experience sampling test study.

BACKGROUND: Epidemiological findings suggest that cannabis use is a risk factor for the emergence of psychosis, and that the induction of psychotic symptoms in the context of cannabis use may be associated with a pre-existing vulnerability for psychosis. This study investigated in a non-clinical population the interaction between cannabis use and psychosis vulnerability in their effects on psychotic experiences in daily life. METHOD: Subjects (N = 79) with high or low levels of cannabis use were selected among a sample of 685 undergraduate university students. Experience sampling method (ESM) was used to collect information on substance use and psychotic experiences in daily life. Vulnerability to develop psychosis was measured using a clinical interview assessing the level of psychotic symptoms. Statistical analyses were performed using multilevel linear random regression models. RESULTS: The acute effects of cannabis are modified by the subject's level of vulnerability for psychosis. Subjects with high vulnerability for psychosis are more likely to report unusual perceptions as well as feelings of thought influence than subjects with low vulnerability for psychosis, and they are less likely to experience enhanced feelings of pleasure associated with cannabis. There is no evidence that use of cannabis is increased following occurrence of psychotic experiences as would be expected by the self-medication model. CONCLUSION: Cannabis use interacts with psychosis vulnerability in their effects on experience of psychosis in daily life. The public health impact of the widespread use of cannabis may be considerable.

Cannabis use and dimensions of psychosis in a nonclinical population of female subjects.

OBJECTIVE: The aim of the present study was to explore the pattern of associations between cannabis use and dimensions of psychosis in a nonclinical population of female subjects. METHOD: The Community Assessment of Psychic Experiences (CAPE), a 42-item self-report questionnaire that evolved from the Peters et al. Delusions Inventory [Schizophr. Bull. 25 (1999) 553], was used to measure dimensions of psychosis in a sample of undergraduate female students (n=571). The participants were also asked to complete a self-report questionnaire collecting information on substance use. RESULTS: Three correlated dimensions of positive, negative and depressive experiences were identified using principal components factor analysis. Frequency of cannabis use was independently associated with the intensity of both positive and negative psychotic experiences. No significant association was found between cannabis use and the depressive dimension, or between alcohol use and any of the three positive, negative and depressive dimensions. CONCLUSION: This cross-sectional study supports the hypothesis that exposure to cannabis may induce the emergence of positive psychotic symptoms in subjects without clinical psychosis, and additionally suggests that cannabis users exhibit greater levels of negative symptoms. Prospective studies are required to explore the direction of causality and the impact of cannabis on the course of psychotic experiences in subjects from the general population.

Antidepressant-induced mania in bipolar patients: identification of risk factors.

BACKGROUND: Concerns about possible risks of switching to mania associated with antidepressants continue to interfere with the establishment of an optimal treatment paradigm for bipolar depression. METHOD: The response of 44 patients meeting DSM-IV criteria for bipolar disorder to naturalistic treatment was assessed for at least 6 weeks using the Montgomery-Asberg Depression Rating Scale and the Bech-Rafaelson Mania Rating Scale. Patients who experienced a manic or hypomanic switch were compared with those who did not on several variables including age, sex, diagnosis (DSM-IV bipolar I vs. bipolar II), number of previous manic episodes, type of antidepressant therapy used (electroconvulsive therapy vs. antidepressant drugs and, more particularly, selective serotonin reuptake inhibitors [SSRIs]), use and type of mood stabilizers (lithium vs. anticonvulsants), and temperament of the patient, assessed during a normothymic period using the hyperthymia component of the Semi-structured Affective Temperament Interview. RESULTS: Switches to hypomania or mania occurred in 27% of all patients (N = 12) (and in 24% of the subgroup of patients treated with SSRIs [8/33]); 16% (N = 7) experienced manic episodes, and 11% (N = 5) experienced hypomanic episodes. Sex, age, diagnosis (bipolar I vs. bipolar II), and additional treatment did not affect the risk of switching. The incidence of mood switches seemed not to differ between patients receiving an anticonvulsant and those receiving no mood stabilizer. In contrast, mood switches were less frequent in patients receiving lithium (15%, 4/26) than in patients not treated with lithium (44%, 8/18; p = .04). The number of previous manic episodes did not affect the probability of switching, whereas a high score on the hyperthymia component of the Semistructured Affective Temperament Interview was associated with a greater risk of switching (p = .008). CONCLUSION: The frequency of mood switching associated with acute antidepressant therapy may be reduced by lithium treatment. Particular attention should be paid to patients with a hyperthymic temperament, who have a greater risk of mood switches.