Confusion about measuring central nervous system effects

Abstract

Anticholinergic therapy together with behavioral treatment are the mainstays of treatment for the overactive bladder. Successful therapy and patient compliance depend very much on side effects. In the past, little attention has been paid to anticholinergic side effects in the central nervous system (CNS), which can be critical, especially for elderly patients. Incidence and intensity of CNS effects depend on the pharmacokinetic and pharmacodynamic properties that are decisive whether anticholinergics pass the blood-brain barrier as a result of passive and active transport mechanisms. To measure potential CNS side effects of anticholinergic drugs, rapid eye movement sleep analysis, quantitative-topographic electroencephalogram studies, and psychometric tests were performed. Structural changes in brain morphology (resulting from anticholinergics) also were analyzed in a postmortem study. However, the data of these studies do not always correlate with clinical experience. The results of clinical studies in elderly patients are also controversial mainly due to the different design of the studies. Spontaneous reporting may not be appropriate, but targeted tests for memory and cognitive function should be applied. Moreover, the treatment period must be adequate. Therefore, further clinical studies in patients with overactive bladder are mandatory, with adequate study design and adequate duration of anticholinergic therapy.