Research report Psychometric properties of the Affective Lability Scale (54 and 18-item version) in patients with bipolar disorder, first-degree relatives, and healthy controls Monica Aas a,b,n , Geir Pedersen a,b , Chantal Henry c,d,e,f,k , Thomas Bjella b , Frank Bellivier e,f,g,h,k , Marion Leboyer c,d,e,f,k , Jean-Pierre Kahn f,j , Renaud F. Cohen f,j , Sebastien Gard f,i , Sofie R. Aminoff a,l , Trine V. Lagerberg b , Ole A. Andreassen a,b,k , Ingrid Melle a,b , Bruno Etain c,e,f,k a NORMENT, KG Jebsen Center for Psychosis Research, Institute of Clinical Medicine, University of Oslo, Norway b NORMENT, Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway c AP-HP, Hôpital H. Mondor – A. Chenevier, DHU Pepsy, Pôle de Psychiatry, Créteil 94000, France d Université Paris Est, Faculté de médecine, Créteil 94000, France e Inserm, U955, Créteil 94000, France f Fondation Fondamental, Créteil, France g AP-HP, GH Saint-Louis – Lariboisière – Fernand Widal, Pôle Neurosciences, Paris 75010, France h Université Paris 7, Denis Diderot, Paris, France i Hôpital Charles Perrens, Centre Expert Trouble Bipolaire, Service de psychiatrie adulte, Pôle 3-4-7, Bordeaux 33000, France j Service de Psychiatrie et Psychologie Clinique, Université de Lorraine et CHU de Nancy, Hôpitaux de Brabois, Vandoeuvre Les Nancy 54500, France k ENBREC, European Network of Bipolar Research Expert Centres (ENBREC), Paris, France l Department of Specialized Inpatient Treatment, Division of Mental Health Services, Akershus University Hospital, 1478 Lørenskog, Norway article info Article history: Received 25 August 2014 Received in revised form 11 October 2014 Accepted 14 October 2014 Available online 23 October 2014 Keywords: ALS original 54 item version (ALS-54) ALS short 18 item version (ALS-18) Psychometric properties Bipolar disorders First-degree relatives Healthy controls abstract Introduction: The aim of this study was to investigate the psychometric properties of the original 54 item version (ALS-54) and the short 18 item version (ALS-18) of the Affective Lability Scale (ALS) in patients with bipolar disorders, their first-degree relatives and healthy controls. Internal Consistency and Confirmatory Factor Analysis were performed, comparing clinical and non-clinical group comparisons on ALS scores. Methods: A total of 993 participants (patients with bipolar disorders [n ¼422], first-degree relatives [n ¼201] and controls [n ¼370]) were recruited from France and Norway. Diagnosis and clinical characteristics were assessed using the Structured Clinical Interview for DSM-IV Axis I disorders (SCID-I), or the Diagnostic Interview for Genetic Studies (DIGS). Affective lability was measured using the ALS-54 and ALS-18. Results: Both ALS-54 and ALS-18 showed high internal consistency, but the subdimensions of both versions were highly inter-correlated. From confirmatory factor analysis both versions revealed acceptable to good model fit. Patients had significantly higher ALS scores compared to controls, with affected first-degree relatives presenting intermediate scores. Conclusion: Both the original ALS-54 version and the short ALS-18 version showed good psychometric properties. They also discriminated between patients with a bipolar disorder (high ALS), first degree relatives (intermediate ALS), and healthy controls (low ALS). A high correlation between ALS items for both versions was observed. Our study supports reducing the scale from 54 to 18 items. & 2014 Elsevier B.V. All rights reserved. 1. Introduction Affective lability can be defined as frequent and intense fluctua- tions in affect in response to both pleasant and unpleasant events (Thompson et al., 2011). Affective lability appears to be an impor- tant feature of several mental disorders, including bipolar disorders Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jad Journal of Affective Disorders http://dx.doi.org/10.1016/j.jad.2014.10.028 0165-0327/& 2014 Elsevier B.V. All rights reserved. n Correspondence to: NORMENT, KG Jebsen Center for Psychosis Research, TOP study group, Division of Mental Health and Addiction, Institute of Clinical Medicine, Bygg 49, Ullevål sykehus, PO Box 4956 Nydalen, 0424 Oslo, Norway. E-mail address: monica.aas@medisin.uio.no (M. Aas). Journal of Affective Disorders 172 (2015) 375–380