Influence of anticholinergic activity in serum on clinical symptoms of Alzheimer's disease

Alzheimer's disease (AD) is well known as a disease characterized by degeneration of cholinergic neuronal activity in the brain. It follows that patients with AD would be sensitive to an 'anticholinergic burden', and also that medicine with anticholinergic properties would promote various clinical symptoms of AD. Despite the relevance of this important phenomenon to the clinical therapeutics of AD patients, few reports have been seen concerning the relationship between anticholinergic burden and clinical AD symptoms. Therefore, we wished to investigate the relationship between serum anticholinergic activity (SAA) and the severity of clinical symptoms of AD patients. Twenty-six out of 76 AD patients referred by practitioners to our hospital were positive for anticholinergic activity in their serum, and the remaining 50 patients were negative. Cognitive and psychiatric symptoms in AD patients were compared between the positive SAA (SAA+) group and the negative SAA (SAA-) group. The SAA+ group showed a significantly (p < 0.05) lower total score on the Mini-Mental State Examination, and significantly (p < 0.05) higher scores on the Functional Assessment Staging and the Behavioral Pathology in Alzheimer's Disease Rating Scale (BEHAVE-AD). In particular, certain subscales of the BEHAVE-AD, i.e. the items of paranoid and delusional ideation, hallucinations and diurnal rhythm disturbances, had higher scores in the SAA+ group. Moreover, it was shown that many more psychotropic medicines were prescribed to the SAA+ group. By means of logistic regression analysis, the items of paranoid and delusional ideation and diurnal rhythm disturbances in the BEHAVE-AD were positively correlated with SAA in patients. We hypothesized that SAA in AD patients would be associated with clinical symptoms, especially delusion and diurnal rhythm disturbances.