Patients with schizophrenia have an increased risk of venous thromboembolism (VTE). The increased risk is more marked among new users and those prescribed atypical antipsychotic drugs. Platelet activation, changes of plasma coagulation, or fibrinolysis are likely to be responsible for the increase in thrombotic events.

In the prospective ANTRE (ANtipsychotics ThRombosis Embolism) study we investigated the plasma levels of markers indicating activation of platelets (soluble P-selectin), coagulation (factor VIII) and fibrinolysis (D-dimers) in a group of thirty patients (seventeen males) with newly diagnosed psychosis (mean age 28.2, range 18–52 years) and in thirty-one healthy volunteers who were matched for age, gender and body mass index. We measured the haemostatic parameters at the time of patients’ admission) and after three and twelve months during outpatient antipsychotic treatment.

At baseline there were significantly increased plasma levels of sP-selectin (P = 0.0003), D-dimers (P = 0.0007) and factor VIII (P = 0.0076) in the group of patients with acute psychosis as compared to healthy volunteers. After three and twelve months of patients’ follow up we still observed increased levels of sP-selectin and D-dimers. Plasma levels of factor VIII were significantly increased after 3 months, but decreased after 12 months.

We found an increase in markers of activation of haemostasis in patients in acute as well as in chronic stage of psychosis. Our results could explain the possible pathological mechanisms of VTE that are independent from antipsychotic treatment and play a role mainly in the acute phase of the disease.