title: Serotonin transporter clustering in blood lymphocytes predicts the outcome on anhedonia scores in naïve depressive patients treated with antidepressant medication.
abstract: BACKGROUND
  We have shown that serotonin transporter (SERT) clustering in blood lymphocytes is altered in major depression and correlates with pharmacological therapeutic responses measured with the Hamilton scale. In the present report, we extend these results to the self-assessment anhedonia scale, as anhedonia is a cardinal symptom of major depression that is difficult to treat with first-line antidepressants.
  
  
  METHODS
  We collected blood samples from 38 untreated depression patients at the time of enrolment and 8 weeks after pharmacological treatment. We used the self-assessment anhedonia scale to evaluate anhedonia symptoms before and after treatment. We also used quantitative immunocytochemistry to measure SERT clusters in blood lymphocytes.
  
  
  RESULTS
  Evaluation of the distribution of SERT clusters size in the plasma membrane of lymphocytes identified two subpopulations of naive depression patients: Depression I (D-I) and Depression II (D-II). While naïve D-I and D-II patients initially showed similar anhedonia scores, D-II patients showed a good response in anhedonia symptoms after 8 weeks of psychopharmacological treatment, whereas D-I patients failed to show any improvement. Psychopharmacological treatment also induced an increase in the number of SERT clusters in lymphocytes in the D-II group, and this increase correlated with the improvement in anhedonia symptoms.
  
  
  CONCLUSIONS
  SERT clustering in peripheral lymphocytes can be used to identify patient response to antidepressant therapy as ascertained by anhedonia scores.
authors.affiliation: Instituto de Investigaciones Biomédicas de Vigo (IBIV), Rebullon Psychiatric Hospital, Vigo, Galicia Spain.
authors.forename: Tania
authors.initials: T
authors.lastname: Rivera-Baltanas
authors.affiliation: Instituto de Investigaciones Biomédicas de Vigo (IBIV), Rebullon Psychiatric Hospital, Vigo, Galicia Spain.
authors.forename: Roberto Carlos
authors.initials: RC
authors.lastname: Agis-Balboa
authors.affiliation: Division of Pharmacy, College of Pharmacy and Nutrition, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5 Canada.
authors.forename: Raquel
authors.initials: R
authors.lastname: Romay-Tallon
authors.affiliation: Division of Neurology, Department of Medicine, College of Medicine, University of Saskatchewan, Saskatoon, SK Canada.
authors.forename: Lisa E
authors.initials: LE
authors.lastname: Kalynchuk
authors.affiliation: Instituto de Investigaciones Biomédicas de Vigo (IBIV), Rebullon Psychiatric Hospital, Vigo, Galicia Spain.
authors.forename: Jose Manuel
authors.initials: JM
authors.lastname: Olivares
authors.affiliation: Division of Pharmacy, College of Pharmacy and Nutrition, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK S7N 5E5 Canada.
authors.forename: Hector J
authors.initials: HJ
authors.lastname: Caruncho
keywords: Biomarker; Depression symptoms; Protein clustering; Psychiatric scales; Serotonin