Background: “Practice effects” (PE), or performance improvements due to prior exposure to testing, are known to confound cognitive test results, particularly when short intervals occur between two test sessions. Objective: We examined two subsamples with short or long re-test intervals from a recent clinical trial. Methods: Thirty-four non-depressed adults with mild Huntington Disease (HD) participated. Three cognitive tests were administered at screening and again at baseline, before active treatment randomization. Half the sample had a 24-hour retest interval while the other half was >6-days. Results: The two groups differed on demographic/clinical factors (age, Total Motor Score and Total Functional Capacity). After controlling for age and motor score, PE differences were found on three of the five UHDRS cognitive tests: the longer interval group showed larger PE on Symbol-Digit Modalities and Stroop color, while the rapid interval group had larger PE on Stroop interference. Controlling for screening cognitive performance yielded similar results. Conclusions: Length of interval between screening and baseline visits and level of disease severity may influence stability of UHDRS cognitive test results in clinical trials in HD.
Practice Effects and Stability of Neuropsychological and UHDRS Tests Over Short Retest Intervals in Huntington Disease
Abstract Background: In Huntington disease (HD), cognitive changes due to disease-progression or treatment are potentially confounded by “practice effects” (PE) — performance improvement from prior exposure to test materials. Objective: A practice run-in (“dual baseline”) was used in an HD cognitive trial to determine if PE could be minimized and evaluate performance trajectories over multiple visits. Methods: Non-depressed adults ( N = 36) with mild to moderate HD-related cognitive deficits participated in a clinical trial to examine the efficacy of citalopram to enhance cognition. Cognitive tests were administered at three visits (2 weeks separating each visit), before active treatment randomization. Some tests were also administered at screening. Therefore 3–4 pre-treatment repetitions were available. We examined test improvement using repeated-measures ANOVAs with planned pairwise comparisons. Results: Despite the practice run-in and use of alternate test forms, results indicated ongoing improvements over at least three test sessions on all three UHDRS cognitive tests. Trails A and B showed improvements between the third and fourth session, which suggests that one pre-baseline visit may not be effective in reducing practice on this important and commonly used test. Conclusions: Overall, 7 out of 13 variables showed some degree of short-term PE, even after multiple sessions and alternate forms. Tests assessing processing speed and memory may be particularly confounded by ongoing PE across at least 2–3 sessions. Practice run-in periods and alternate forms may help minimize the impact of such effects in HD clinical trials but awareness of which tests are most susceptible to PE is important in clinical trial design.
Results of the citalopram to enhance cognition in Huntington disease trial
AbstractBackgroundHematopoietic stem cell transplant (HSCT) recipients have increased morbidity from respiratory viral infections. Pandemic influenza A – A(H1N1)/pdm09 – in 2009–2010 was associated with increased severity of illness in patients with underlying co‐morbidities including HSCT, but the factors that contribute to severe disease in HSCT patients are not well characterized.MethodsWe conducted a multicenter review of microbiologically proven influenza A(H1N1)pdm09 in the HSCT population between April 2009 and April 2010 to determine factors that are associated with severe disease.ResultsWe identified 37 adult patients (26 allogeneic and 11 autologous HSCT recipients). Median time from transplant to diagnosis was 411 days (range 4 days–14.9 years). Three cases were hospital acquired. Twenty‐eight of 37 (75.7%) had confirmed A(H1N1)pdm09. Presumed viral lower respiratory tract infection was present in 12/37 (32.4%) patients. Antiviral therapy was given to 33/37 (89%) patients, primarily oseltamivir (n = 24) and oseltamivir before or after another antiviral (n = 8). Excluding those with nosocomial A(H1N1)pdm09, 18/34 (52.9%) were hospitalized and 6 (33%) required admission to an intensive care unit. Mortality within 30 and 60 days of symptom onset was 7/37 (18.9%) and 11/37 (29.7%), respectively. Factors associated with mortality included nosocomial acquisition (P = 0.023), receipt of mycophenolate mofetil (P = 0.001), or antilymphocyte antibody (P = 0.005) within the past 6 months, reduced‐intensity conditioning (P = 0.027), and bacteremia (P = 0.021).ConclusionsA(H1N1)pdm09 infection was particularly severe in HSCT recipients, specifically among those receiving augmented immunosuppression for graft‐versus‐host disease. The high mortality of the nosocomial cases highlights the need for strict infection‐control measures in hospitals during influenza outbreaks.