Platelet phenolsulphotransferase activity, monoamine oxidase activity and peripheral-type benzodiazepine binding in demented patients.

Blood platelet phenolsulphotransferase and monoamine oxidase activities, as well as platelet peripheral-type benzodiazepine binding have been studied in several neuropsychiatric disorders, in order to identify biochemical markers for altered brain functioning. In the present work, we determined platelet phenolsulphotransferase and monoamine oxidase activities in demented patients: they showed significantly higher phenolsulphotransferase and monoamine oxidase activities than controls. A significant positive correlation was found between enzyme activities and severity of illness. In the same subjects, we evaluated platelet peripheral-type benzodiazepine binding: a significant reduction of Bmax values was observed in demented patients, whereas Kd values did not substantially differ between the two subject groups. These findings are discussed with reference to central nervous system biochemical abnormalities of demented subjects: it may be that in Dementia of Alzheimer type either some central biochemical changes are reflected in certain peripheral tissues (such as platelets), or a systemic derangement occurs together with a cerebral involvement.