engleski

Platelet serotonin and monoamine oxidase and plasma dopamine-beta hydroxylase as peripheral biochemical markers in early and late onset Alzheimer's disease

Introduction. Alzheimer's disease (AD) is a chronic and progressive, multifactorial and complex disorder. Post mortem brain studies indicated that the alterations in the neurotransmitter system could be involved in the etiology and progress of AD. The age at onset and the course of AD could be related to the lifestyle, genetic, spciodemographic, environmental, clinical and pharmacological factors. The objective of the study was to determine peripheral biochemical markers (platelet serotonin/5-HT/ concentration, and the activity of platelet monoamine oxidase type B /MAO-B/ and plasma dopamine-beta hydroxylase /DBH/) in patients with AD subdivided according to the onset of disease and presence of psychotic features. Subjects & Methods. Each diagnosis of the probable AD fulfilling NINCDS-ADRDA criteria was established by two psychiatrists according to the ICD-10 and DSM-IV-TR criteria. Cognitive impairment was evaluated using the Mini Mental Status Examination (MMSE). The study included 43 male and 144 female patients with AD subdivided in two groups according to early (before age 64) or late (after age 65) onset AD. Control group consisted of sex- and age-matched medication free healthy subjects (65 female and 51 male). Platelet 5-HT concentration and platelet MAO-B activity were determined using spectrofluorimetric methods, and plasma DBH using photometric method. Results. The changes in biochemical parameters were not related to the presence of psychotic features. Platelet 5HT concentration and plasma DBH activity were decreased, while platelet MAO-B activity was increased in patients with AD. The highest platelet MAO-B activity was found in male and female patients with early onset AD. Patients with late onset AD had lower values of plasma DBH activity as compared with patients with early onset AD and healthy controls. Conclusions. The results from our ongoing study support the presumption that platelet 5-HT concentration, platelet MAO-B and plasma DBH activity could be used as peripheral biological markers for different categories of AD. In addition, high platelet MAO-B and low plasma DBH activity could be used as predictors of AD. Our results of the altered MAO-B and DBH activity in patients with AD support the presumption that toxic and reactive metabolites of catecholamine neurotransmitters could be involved in the etiology of AD.

platelet; plasma; marker; Alzheimer's disease

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