Number of platelet dense granules varies with age, schizophrenia and dementia.

In the present study we observed that the number of dense granules per platelet increases with age, attaining a maximum level above the age of about 40 years. Platelets of newborns apparently contain only a small number of dense granules per platelet. The numbers of platelet dense granules and platelet cell size in schizophrenic patients increase compared to age-matched healthy controls. In contrast, in Alzheimer-type dementia the number of platelet dense granules tends to decrease compared to healthy persons.