Significant correlation between plasma and CSF anticholinergic activity in presurgical patients

Previous studies have suggested a possible link between cognitive impairment and anticholinergic burden as reflected by high serum anticholinergic activity (SAA). Thus, we hypothesized a close relationship between anticholinergic activity in cerebral spinal fluid (CSF) and blood. However, it has never been convincingly demonstrated that peripheral anticholinergic activity correlates with central anticholinergic levels in presurgical patients. Therefore, anticholinergic activity was measured in blood and CSF from 15 patients with admission scheduled for urological surgery to compare peripheral and central anticholinergic level. Blood and CSF probes were taken after routine premedication and before spinal anesthesia. Anticholinergic activity was determined by competitive radioreceptor binding assay for muscarinergic receptors. Correlation analysis was conducted for peripheral and central anticholinergic levels. The mean anticholinergic levels were 2.4+/-1.7 in the patients' blood and 5.9+/-2.1 pmol/mL of atropine equivalents in CSF. Interestingly, the anticholinergic activity in CSF was about 2.5-fold higher than in patients' blood. A significant linear correlation was detected between blood and CSF levels. Therefore we conclude that SAA levels adequately reflect central anticholinergic activity. When patients receiving or not receiving anticholinergic medication were compared, anticholinergic activity tended to increase in blood and CSF after receiving anticholinergic medication > or =4 weeks (p>0.05).