The prevalence effect in a laboratory environment: Changing the confidence ratings. (9/59)

RATIONALE AND OBJECTIVES: We sought to assess whether or not prevalence levels affected the confidence ratings of readers during the interpretation of cases in a laboratory receiver operating characteristic-type observer performance study. MATERIALS AND METHODS: We reanalyzed a previously conducted observer performance study that included 14 readers and 5 different levels of prevalence. The previous study yielded the observation that in the laboratory we could not detect a "prevalence effect" in terms of differences in areas under the receiver operating characteristic curves. The detection ratings (for presence or absence) of lung nodules, interstitial disease, and pneumothorax for the five prevalence levels were compared, and a test for trend in averaged ratings as a function of abnormality prevalence was performed within a mixed-model setting that accounts for different sources of variability and correlations induced by the study design. RESULTS: The ratings of the cases in terms of confidence that the specific abnormality in question is present tend, on average, to be larger when actual disease prevalence is lower. The rate of the increase of the average confidence ratings with the decreasing prevalence of a specific abnormality is very similar for actually positive and actually negative cases for every considered abnormality. The observed trend in the changes of the average confidence ratings as a function of prevalence levels was statistically significant (p < 0.01). CONCLUSION: Expectations of disease prevalence in the case mix during a laboratory observer performance study may systematically affect the behavior of observers in terms of their actual confidence ratings.  (+info)

Modulation of quinpirole-induced compulsive-like behavior in rats by environmental changes: implications for OCD rituals and for exploration and navigation. (10/59)

BACKGROUND: Rats treated chronically with the D2-3 dopamine agonist quinpirole were previously proposed as an animal model of obsessive-compulsive disorder (OCD) since their behavior is based on repeated, compulsive-like persistent traveling between a few places in the open field. The aim of the present study was to determine properties of the physical environment that shape such behavior. For this, quinpirole-treated rats were first exposed to an arena with an array of objects (landmarks) and after the development of compulsive-like behavior, the arena was manipulated by multiplying the number of objects, changing their spacing, relocating object array, or removing the objects. RESULTS: When the number of objects was retained but they were spaced further apart, rat routes converged at 1-2 of the objects and at the corner at which the rats had been introduced into the arena (start corner). When object spacing was retained but their number was increased, the rats traveled between the objects with the routes converging only at the start corner. Finally, when object array was relocated to different places within the arena, the rats extended their routes from the start corner to the object array, regardless of array location. CONCLUSION: Quinpirole-treated rats organized and updated their progression primarily according to the proximal layout of landmarks, but did so with excessive repetitions compared with saline-treated rats. The behavior of quinpirole-treated rats paralleled human OCD rituals that are linked to the immediate physical environment, featuring an excessive rate of performance. Finally, when only a few objects were present, they were perceived by the rats as positional cues (beacons) that routes converged at them. In contrast, in the presence of many objects, the routes passed between the objects as if using them as directional cues.  (+info)

Thirty cases of obsession treated by point-stimulation and with small dose of chlorimipramine. (11/59)

OBJECTIVE: To investigate the clinical therapeutic effects of point-stimulation for obsession. METHODS: Sixty cases of obsession were divided into two groups: a control group of 30 cases treated with chlorimipramine (Chl), and a treatment group of 30 cases treated by point-stimulation (PS) plus chlorimipramine (PS+Chl). The therapeutic effects and side-effect were evaluated according tb the criteria set in Yale-Brown Obsession Scale (Y-BOCS), Hamilton's depression scale (HAMD), brief psychiatric rating scale (BPRS) and treatment emergent symptom scale (TESS). RESULTS: The cure rate and markedly effective rate were respectively 26.7% and 56.6% in the control group, and 43.3% and 50% in the treatment group, suggesting that the therapeutic effect in the treatment group was better than that in the control group. The incidence of adverse side-effects was 73.33% in the control group and 46.67% in the treatment group, with a significant difference between the two groups (P<0.05). CONCLUSION: Point-stimulation plus small dose of chlorimipramine was superior to the simple chlorimipramine treatment, indicating that the combined method was more effective and safe for obsession with less side effects.  (+info)

Why did the white bear return? Obsessive-compulsive symptoms and attributions for unsuccessful thought suppression. (12/59)

The current study examined the nature and consequences of attributions about unsuccessful thought suppression. Undergraduate students with either high (n=67) or low (n=59) levels of obsessive-compulsive symptoms rated attributions to explain their unsuccessful thought suppression attempts. We expected that self-blaming attributions and attributions ascribing importance to unwanted thoughts would predict more distress and greater recurrence of thoughts during time spent monitoring or suppressing unwanted thoughts. Further, we expected that these attributions would mediate the relationship between obsessive-compulsive symptom levels and the negative thought suppression outcomes (distress and thought recurrence). Structural equation models largely confirmed the hypotheses, suggesting that attributions may be an important factor in explaining the consequences of thought suppression. Implications are discussed for cognitive theories of obsessive-compulsive disorder and thought suppression.  (+info)

Schizotypal personality traits in Gilles de la Tourette syndrome. (13/59)

OBJECTIVES: Gilles de la Tourette syndrome (GTS) is a chronic tic disorder associated with comorbid psychopathology, including obsessionality, affective instability and attention-deficit hyperactivity disorder. Evidence linking GTS with schizophrenia-like symptoms is limited and equivocal, despite a common putative substrate involving dopaminergic dysfunction within frontostriatal circuits. The aim of this study was to quantify the prevalence of schizotypal traits in GTS and to detail the relationship between schizotypy and comorbid psychopathology. MATERIALS AND METHODS: A total of 102 subjects with GTS were evaluated using the Schizotypal Personality Questionnaire and standardized neurological and psychiatric rating scales. The predictive interrelation between schizotypy, tic-related symptoms and psychiatric comorbidities was investigated using correlation and multiple regression analyses. RESULTS: In our clinical population, 15% of the subjects were diagnosed with the schizotypal personality disorder according to the DSM-IV criteria. The strongest predictors of schizotypy were obsessionality and anxiety ratings. The presence of multiple psychiatric comorbidities correlated positively with schizotypy scores. CONCLUSIONS: Schizotypal traits are relatively common in patients with GTS, and reflect the presence of comorbid psychopathology, related to the anxiety spectrum. In particular, our preliminary results are consistent with a shared neurochemical substrate for the mechanisms underpinning tic expression, obsessionality and specific schizotypal traits.  (+info)

Mood parameters and severe physical symptoms of the female reproductive cycle. (14/59)

OBJECTIVE: The cyclic variation of physical and psychological phenomena has been accepted as a natural consequence of the cyclicity of the human female reproductive function. The exact nature of these changes, however, has not been fully understood. The aim of our study was to investigate the fluctuation of psychological and physical symptoms throughout the female reproductive cycle in healthy, non-PMDD women. METHOD: 63 psychiatrically healthy, non-PMDD women with normal regular menstrual cycles and not using hormonal contraceptive methods participated in the study. Participants completed the PRISM calendar every night for three consecutive cycles and on three predefined days of the first cycle they completed several other psychometric measures (SCL-51, STAI, ZSDS, EAT and Mind and Body Cathexis Scale). Based on an at least 66% increase in physical symptoms from the late follicular to the late luteal phase on the PRISM, subjects were assigned to LPPS (luteal phase physical symptoms) and nonLPPS (no luteal phase physical symptoms) groups. Average of psychometric scores obtained at the three predefined days were compared between the two groups. RESULTS: There was a significant difference between the two groups only in case of the interpersonal sensitivity subscale of the SCL-51. CONCLUSION: Our results indicate that the appearance of severe physical symptoms in the late luteal phase of the female reproductive cycle is not accompanied by a worsening of psychological symptoms. The appearance of enhanced psychological symptomatology attributed to the luteal phase of the female reproductive cycle thus seems to be independent of the appearance of severe physical symptoms.  (+info)

Obsessive and compulsive symptoms in prediagnosed Huntington's disease. (15/59)

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Prevalence of psychopathology in childhood epilepsy: categorical and dimensional measures. (16/59)

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