Functional Equivalence of WAIS-III/WMS-III Digit and Spatial Span under Forward and Backward Recall Conditions

The purpose of the current study was to examine the performance characteristics of the Wechsler Spatial Span subtest in a mixed clinical sample. Contrary to expectation, differential patterns of performance were obtained on the Digit and Spatial Span tasks. Forward Digit Span scores were significantly higher than backward recall scores, but this was not the case for Spatial Span. There were no differences between forward and backward raw Spatial Span scores at the mean level. Further, about one third of the sample showed better performance on backward compared to forward Spatial Span. In addition, performance on the Spatial Span backward task correlated unexpectedly with that of the WMS-III Immediate and Delayed Auditory Index scores. Overall, the findings suggest that clinicians should be hesitant when interpreting the Spatial Span task, and the backward condition in particular, as a measure of working memory. Finally, methodological concerns with the Spatial Span task are noted, raising additional concerns regarding the meaning of this task.     

Using Intraindividual Variability to Detect Malingering in Cognitive Performance

The utility of measures for detecting malingering was evaluated using a simulation design in which half the participants were encouraged to do their best and half were asked to feign head injury. Particular attention was focused on the utility of repeated assessment (intraindividual variability) in discriminating the groups. Participants were tested on three occasions on measures commonly used to detect malingering including a specific symptom validity test (SVT). The results indicated that multiple measures of malingering obtained in single assessment (occasion one) discriminated the groups effectively. In addition, however, intraindividual variability in performance, particularly of indicators from the SVT, provided unique information beyond level of performance. The results suggest that response inconsistency across testing sessions may be a clinically useful measure for the detection of malingering.     

Lymphocyte Subpopulations,Oxidative Burst and Apoptosis in Peripheral Blood Cells of Patients with Multiple Sclerosis–Effect of Interferon-β

At present, the most efficient therapeutical treatment of multiple sclerosis (MS) is achieved by IFN-β. However, its in vivo effects remain incompletely understood. If applied parenterally, the hydrophobic IFN-β acts primarily on blood cells with probable selectivity for functionally different lymphocyte subpopulations, monocytes and granulocytes. We have investigated the expression of the activation marker interleukin-2 receptor-α (CD25) on CD3⁺ T cells, CD19⁺ B cells, foetal-type γδ⁺CD3⁺ T cells and foetal-type CD5⁺CD19⁺ B cells of the peripheral blood. In addition, the oxidative burst activity and apoptosis have been determined in mononuclear and polymorphonuclear blood cells, respectively. The study accompanied a phase III trial with IFN-β1b (BETAFERON^®, Schering). Two groups of MS patients with relapsing-remitting course of the disease have been investigated at 8 time points (days 0, 5, 15, 31, 60, 90, 180 and 270 after starting therapy): (1) verum group (n=8) with application of 8 Mill. units IFN-β1b every other day, and (2) placebo group (n=4) with application of placebo for 3 months and therapy as in (1) from day 90 onward. The main results were: (1) Activated T cells decreased until day 180 in the verum group and return thereafter to pre-treatment values, whereas in the placebo group the values remained relatively stable over the whole observation period. (2) Activated B cells increased between days 90 and 270 in both groups, i.e. after verum application in both groups. (3) Foetal-type B cells were more activated than total B and T cells with increase over time in both groups. (4) Foetal-type T cells exerted relatively stable intra-individual levels with generally low CD25 expression, but punctual CD25 peaks in both groups. (5) The spontaneous oxidative burst was higher in lymphocytes, more variable in monocytes and faster increasing in granulocytes in the verum group than in the placebo group. (6) Apoptosis of mononuclear cells and granulocytes showed similar variations in the verum and placebo groups with the exception of a selective increase over time of the proportion of granulocytes undergoing induced apoptosis in the verum group. It is concluded that IFN-β has the following main effects on the immune system of MS patients: (1) the T cell immunity is systemically and reversibly suppressed, (2) the foetal-type lymphocytes, which are responsible for the first line of defence of infections, are stimulated in the long range, (3) the oxidative burst activity is increased in lymphocytes and granulocytes and instable in monocytes, and (4) the inducibility of apoptosis in granulocytes is increased. Re-examination of the altered blood cell parameters after long-term IFN-β therapy is warranted.