1. ¹Institute of Psychiatry, University of Bologna, Bologna, Italy
2. ²Department of Neuropsychiatry, Kansai Medical University, Osaka, Japan
3. ³Neurogenetics Section, Centre for Addiction and Mental Health (CAMH), University of Toronto, Toronto, Ontario, Canada

Correspondence: Dr A Serretti, Department of Psychiatry, University of Bologna, Viale Carlo Pepoli 5, Bologna 40123, Italy. E-mail: alessandro.serretti@unibo.it

Received 1 January 2007; Revised 20 June 2007; Accepted 9 July 2007; Published online 7 August 2007.

Abstract

Pharmacogenetic studies in mood disorders are rapidly proliferating after the initial reports linking gene variants to treatment outcomes. However, a considerable range of methodologies has been used, making it difficult to compare results across studies and limiting the representativeness of findings. Specification of sampling source (inpatients vs outpatients, primary vs tertiary settings), standardization of diagnostic systems and treatments, adequate monitoring of compliance through plasma levels, sufficient length of observation (at least 6 weeks for acute antidepressant treatments, though 3–6 months are preferable), the use of a range of response criteria and the inclusion of possible environmental confounding variables (life events, social support, temperament) are all potentially important issues when planning pharmacogenetic studies. We reviewed the state-of-the-art methodology and suggested possible guideline for future studies.