Cognitive planning deficits affect patients with Parkinson's disease (PD) and traditional psychometric tests meet difficulties to evaluate their impact on daily life activities. Virtual reality (VR) may provide a new means of assessment. The objective of this study was firstly to develop a virtual environment (VE) useful to explore planning and secondly to examine the effectiveness of using VR in the assessment of cognitive planning for patients with PD. A virtual supermarket (VS) was designed in which participants carried out a task close to daily activities: a test of shopping list. There were two preliminary sessions to familiarize the participants with the software and the supermarket's layout. Then, during the assessment session, participants completed the task, without any time limitation. Global intellectual efficiency was assessed in order to exclude patients with dementia. Data related to the performance in the VS were recorded. Five patients with PD and five age-matched healthy volunteers, meeting inclusion criteria, constituted our convenience sample. The patients did not perform as well as the control group. In particular, the session's duration and the distance covered were longer. The patients' path is specific with numerous stops, turning around, and hesitancies. Finally, their motivation for further training sessions is aroused. The results underline the potential of using VR in the assessment of cognitive planning in PD. A larger analysis is currently being carried out to confirm and to explore all the outcome measures.
Background: Silymarin is a well-known hepatoprotective agent. Tacrine, the first drug marketed for Alzheimer’s disease (AD), induces an elevation of serum liver transaminase prohibiting an effective dosage in many patients. This 12-week randomised, double-blind, placebo-controlled study was undertaken to evaluate the ability of silymarin to antagonise or prevent the hepatotoxic effects of tacrine and to analyse its action on tacrine efficacy and tolerability. Methods: Outpatients suffering from mild-to-moderate dementia of the Alzheimer type were randomly assigned to two treatment groups: tacrine + silymarin and tacrine + placebo. The study was double-blind for silymarin and open for tacrine and was conducted in 22 French neurology and geriatric centres. Silymarin (420 mg/day) was given first (1 week) and tacrine was added at 40 mg/day for 6 weeks, then increased to 80 mg/day (6 weeks). Serum ALAT was the main evaluation criterion (> upper limit of normal, ULN). Serum ASAT as well as adverse side effects and cognitive performance assessed by MMSE and the Syndrome Kurtz test (SKT) were secondary evaluation criteria. Null hypotheses were evaluated with Fisher’s exact test. Findings: 222 patients were recruited and received silymarin and tacrine (110 patients) or placebo and tacrine (112 patients). 28 patients dropped out; 217 were included in the intent-to-treat analysis. No statistical difference was observed between the two groups for serum ALAT (p = 0.39). Fewer patients had ALAT levels >5 ULN in the silymarin group (–33.3%). Side effects and notably gastrointestinal disorders were much less frequent in the silymarin group. Cognitive performance remained unchanged in both groups. Interpretation: Silymarin does not prevent tacrine-induced ALAT elevation but does reduce the rate of gastrointestinal and cholinergic side effects without any impact on cognitive status. As a consequence, silymarin (420 mg/day) could be co-administered with tacrine to improve tolerability in the initial phases of AD treatment.
Methodology used for the development of anti-Alzheimer's disease (AD) drugs raises specific problems which are rarely examined in the literature. While the general development scheme is similar to that required for most drugs, some specific aspects must be analyzed, highly dominated by the dual goal of pharmacology, i.e., to obtain both symptomatic and etiopathogenic drugs. During preclinical studies, aged or lesioned animals are mainly useful for symptomatic drugs, whereas transgenic models or neurodegeneration-induced techniques would probably lead to etiopathogenic drugs potentially slowing down the process of AD. The first administrations of a new compound to human beings raise the question of the activity measurement techniques. Psychometry remains the most informative procedure to detect and analyze the activity of the drugs on the different components of cognition. Electrophysiology and neuroimaging need some complementary studies before they can be proposed as surrogate criteria in phase III trials. At this stage of development, American and the recently published European guidelines are of great help while insisting on long-term (6 months) placebo controlled trials with the use of the triple efficacy criterion: an objective cognition scale, a global assessment, and the opinion of the caregiver. In the long term, pharmacoepidemiology and pharmacoeconomy will have to confirm the rationale of this recent progress in the methodology of anti-AD drug development.
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