Nelson Hauck Filho

Establishing a clinically relevant cutoff to the Dependency Scale from the dimensional clinical personality inventory

The Clinical Dimensional Personality Inventory (IDCP) is a 163-item self-report tool developed for the assessment of 12 dimensions of personality pathology. One of the scales comprising the instrument-the Dependency scale-is intended to provide psychometric information on traits closely related to the Dependent Personality Disorder (DPD). In the present study, we used both Item Response Theory modeling and Receiver Operating Characteristic curve analysis to establishing a clinically meaningful cutoff for the IDCP Dependency Scale. Participants were 2.481 adults, comprised by outpatients diagnosed with DPD, outpatients diagnosed with other PDs, and adults from the general population. The Wrights item map graphing technique revealed that outpatients were located at the very high levels in the latent scale continuum of the Dependency Scale, with a very large effect size for the mean difference between patients and non-patients. The ROC curve analysis supported a cutoff at 2.3 points in the Dependency Scale, which yielded 0.86 of sensitivity and 0.79 of specificity. Findings from the present investigation suggest the IDCP Dependency Scale is useful as a screening tool of the core features of the DPD. We address potential clinical applications for the instrument, and discuss limitations from the present study.

Comprometimento Executivo nas Fases Leve à Grave da Doença de Parkinson

A Doenca de Parkinson (DP) e uma desordem neurodegenerativa caracterizada por disfuncoes motoras, mas tambem marcada por alteracoes executivas. O presente estudo investigou funcoes executivas em individuos saudaveis e pacientes parkinsonianos com grau variavel de comprometimento. Foram avaliados 30 controles saudaveis e 40 pacientes com DP utilizando os instrumentos Hoehn e Yahr, WAIS-III, MEEM, MoCA, Stroop e BADS. Pacientes com DP evidenciaram significativo prejuizo nas funcoes executivas, quando comparados as pessoas do grupo controle. Houve um percentual de 72,5% de pacientes com disfuncao executiva (DE), distribuidos em todos os estagios da DP, sendo que mulheres, individuos com menor escolaridade e aqueles com idade avancada apresentaram disfuncoes mais severas do que os demais pacientes. Portanto, o numero de pacientes com alteracoes executivas foi significativo, nao estando estas relacionadas ao agravamento da doenca. No entanto, algumas variaveis dos individuos da amostra se mostraram protetivas para o agravamento das disfuncoes.

Effects of statistical models and items difficulties on making trait-level inferences : a simulation study

Researchers dealing with the task of estimating locations of individuals on continuous latent variables may rely on several statistical models described in the literature. However, weighting costs and benefits of using one specific model over alternative models depends on empirical information that is not always clearly available. Therefore, the aim of this simulation study was to compare the performance of seven popular statistical models in providing adequate latent trait estimates in conditions of items difficulties targeted at the sample mean or at the tails of the latent trait distribution. Results suggested an overall tendency of models to provide more accurate estimates of true latent scores when using items targeted at the sample mean of the latent trait distribution. Rating Scale Model, Graded Response Model, and Weighted Least Squares Mean- and Variance-adjusted Confirmatory Factor Analysis yielded the most reliable latent trait estimates, even when applied to inadequate items for the sample distribution of the latent variable. These findings have important implications concerning some popular methodological practices in Psychology and related areas.