Diagnostic tests yield measurements on very different types of scales. Quantitative scales may consist of non-negative integers, either unbounded or bounded, with a fixed number of different values, or they may consist of continuous or percentage values. Remembering a different threshold value for each diagnostic variable would be cumbersome, in particular if covariates have to be taken into account. As a convenient way to overcome such problems we propose to compute z-scores for all measurements. They will be adjusted for covariates so that any individual can be judged on any test result on one single scale with an appropriate standard normal quantile as threshold. Two issues need to be addressed: Selection of covariates in the regression model which delivers the adjustment and normality of the residuals. The first will be treated by cross-validation and the latter by applying an appropriate transformation. We apply this methodology to neuropsychological tests and adjust for age, length of education and sex. Normality of residuals is needed on the diagnostically relevant side only. This allows to use parametric transformations, which can be easily implemented, e.g. in database systems. Since we have measurements at baseline and at follow-up we also analyze change values in a similar manner. For ease of interpretation, we transform the resulting z-scores back to the original scale.
The epsilon4 allele of the ApoE gene has a negative impact on cognitive performance, notably on episodic memory functions, in physically and mentally healthy aged persons. Practice effects seen in carriers of the ApoE epsilon4 were inferior in most areas tested to the effects seen in ApoE epsilon4 non-carriers. Further follow-up of these subjects will help to determine the clinical significance of these findings.
The new diagnostic criteria for mild cognitive impairment (MCI) from the International Working Group on Mild Cognitive Impairment (Winblad et al., 2004, p. 243) list "evidence of decline over time in objective cognitive tasks" as one diagnostic sign, implying the repeated neuropsychological testing. This study aimed to compare different assessment methods of longitudinal change based on the performances of 366 cognitively healthy participants (237 men, 129 women) examined with a German version of the California Verbal Learning Test (Delis, Kramer, Kaplan, & Ober, 1987) at baseline and 2 years later. Age, education, gender, and baseline performance were taken into account. Results revealed marked practice effects after 2 years. Normal ranges for change that controls for practice effects and regression to the mean proved to be superior to other reliable change indexes. This new method allows for more valid interpretation of change in neuropsychological functioning and thus diagnosis of MCI.
Background In a high proportion of patients with favorable outcome after aneurysmal subarachnoid hemorrhage (aSAH), neuropsychological deficits, depression, anxiety, and fatigue are responsible for the inability to return to their regular premorbid life and pursue their professional careers. These problems often remain unrecognized, as no recommendations concerning a standardized compre-
Neuropsychological outcome is underreported, and there is great variety in assessment in currently published clinical articles on aSAH. Prospective randomized trials treating aSAH may benefit from implementing more comprehensive and standardized neuropsychological outcome measures. This approach might identify otherwise unnoticed treatment effects in future interventional studies of aSAH patients.
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