Platelet serotonin concentration and monoamine oxidase type B activity in female patients in early, middle and late phase of Alzheimer's disease

Coated-platelet levels and progression from mild cognitive impairment to Alzheimer disease

“…19 Previous investigators have examined a possible role of platelets as either a surrogate indicator of putative events involved in AD or as reservoirs of telltale amyloid markers. In the first instance, abnormal serotonin content, 23 mitochondrial function, 24 and nitric oxide abnormalities 25 in platelets have been observed in platelets from patients with AD. In the second instance, several studies have examined the presence of abnormal amyloid isoforms in advanced AD.…”

Monoamine oxidase inhibitors: Promising therapeutic agents for Alzheimer’s disease (Review)

“…This was demonstrated by [ 11 C]-L-deprenyl using whole hemisphere autoradiography (38)(39)(40), epidemiology (41,42), morphology (43), as well as single-photon emission computed tomography (44). Such studies demonstrated that: i) MAO activity in platelets was significantly increased in patients with AD and acted as a marker of behavioral characteristics in dementia disorders (41,(45)(46)(47)(48); ii) there were early and persistent alterations in MAO-A and -B in the brains of patients with AD (49); iii) activated MAO led to cognitive dysfunction (50); iv) activated MAO destroyed cholinergic neurons and caused disorders of the cholinergic system (51); v) activated MAO contributed to the formation of amyloid plaques (13,14) and vi) activated MAO was associated with the formation of NFTs.…”

“…An increased activity of this enzyme may constitute a marker for vulnerability towards behavioral disturbance (47). According to a Mini Mental State Examination (MMSE) of three groups with 23 patients in the early (MMSE score of [19][20][21][22][23][24], 23 patients in the middle (MMSE score of 10-18) and 28 patients in the late (MMSE score of 0-9) phases of AD, as well as 49 age-matched healthy females, significant correlations between MMSE scores and MAO-B activity and age were identified, suggesting that these markers may indicate the severity and/or clinical progress of AD (42,45).…”

Comparative platelet proteome analysis reveals an increase of monoamine oxidase-B protein expression in Alzheimer's disease but not in non-demented Parkinson's disease patients

“…In reference to the proposed immunological kit for measuring Mao-B in probable AD patients, a recurring issue in the literature is an apparent lack of reproducibility between the measurements reported in studies regarding the Mao-B enzyme activity in PD and AD patients based on the different methods used to isolate platelets from blood [15,59,64,65]. Hence, it might not be considered optimal to use Mao-B activity as a biomarker in routine analysis, and instead it is likely that the quantification of the level of Mao-B protein will turn out to be more reliable.…”

“…The issue of elevated Mao-B activity in platelets and brain tissue in AD [10] is not altogether incontovertible, since a more recent study reported that platelet Mao-B activity does not change in platelets of early and middle stages of AD patients whereas in late stages the activity is actually reduced [15]. Hence, it is critically important to be able to quantify differences in intracellular Mao-B protein levels in neurons, platelets or any other homogenous cell population of AD patients [16].…”