Alzheimer and platelets: low-density platelet populations reveal increased serotonin content in Alzheimer type dementia

Clin Biochem. 2014 Oct;47(15):51-3. doi: 10.1016/j.clinbiochem.2014.07.007. Epub 2014 Jul 17.


Introduction: Alzheimer's disease (AD) is a progressive form of dementia characterized by an increase in the toxic substance β-amyloid in the brain. Platelets display a substantial heterogeneity with respect to density. They further contain a substantial amount of β-amyloid precursor protein. Platelets take up and store serotonin (5-HT) that plays an important role in the pathogenesis of severe depression. The current study aims to investigate platelet serotonin content in different platelet density populations.

Material and methods: The study involved 8 patients (age 70±8 (SD) years) (3 females/5 males) with moderate AD. 6 healthy elderly subjects (age 66±9 (SD) years) (3 females/3 males) served as controls. The platelet population was divided into 17 subpopulations according to density, using a linear Percoll™ gradient. Platelets were counted in all fractions. After cell lysis an ELISA technique was employed to determine the 5-HT content in each platelet subfraction.

Results: The two study groups did not differ significantly regarding platelet distribution in the gradients, but AD sufferers have a significantly higher 5-HT content (p<0.05) in the lighter platelet populations.

Discussion: AD-type dementia proved to be associated with lighter platelets containing more 5-HT. It is possible that platelets from AD patients release less 5-HT. It is speculated that AD synapses are affected in a manner comparable to platelets, which could explain why 5-HT reuptake inhibitors are less effective in AD dementia.

Keywords: Alzheimer's disease; Fibrinogen; Platelet activity; Platelet density; Platelet heterogeneity; Platelets; Serotonin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Alzheimer Disease / blood*
  • Alzheimer Disease / pathology
  • Amyloid beta-Peptides / metabolism*
  • Blood Platelets / metabolism*
  • Blood Platelets / pathology
  • Female
  • Humans
  • Male
  • Serotonin / blood*


  • Amyloid beta-Peptides
  • Serotonin