Table 1: Prevalence of affective disorders before surgery.

Author and Publication year	Country	Study features	N Participants	Mean age	Sex	Other features of the study	Surgery/Setting	Instruments	Results
Da Silva et al. 2015 [34]	Marseille (France)	Retrospective study	92	/	/	Focusing on lifetime mood disorders prevalence	Candidates to surgery	Standardized evaluation of psychiatric comorbidity	Lifetime mood disorders prevalence: 33 % bipolar disorder, 29 % depressive disorder. 48 % of patients suffering from bipolar disorder were previously diagnosed as suffering from major depressive disorder. 60 % of the patients suffering from major depressive disorder were not considered to have any mood disorder.
Grothe KB et al. 2014 [31]	Rochester (MN-USA)	Retrospective study	935	47.4 ± 12.3 years	75% F	Bipolar disorder prevalence	Candidates to surgery	Mood Disorder Questionnaire (MDQ); BDI-II	5.8% of the preoperative sample screened positive for symptoms of BD, 22% of BD patients underwent bariatric surgery.
Duarte-Guerra LS et al. 2014 [32]	Sao Paulo, Brazil	Retrospective study	393	43	79.1% F	To replicate previous findings on frequency of psychiatric disorders and associated factors among obese patients seeking bariatric surgery	Candidates to surgery	SCID-I	Current anxiety disorders 46.3%; lifetime psychiatric disorders 80.9%; lifetime affective disorders 64.9%, bipolar disorders 35.6%, depressive disorders 29.3%.
Salwen JK et al. 2014 [30]	New York	Retrospective study	187			Childhood abuse and adult interpersonal abuse prevalence	Candidates to surgery		61% childhood abuse, 30.5% adult interpersonal abuse, 15% depressive symptoms.
Hayden MJ et al. 2014 [36]	Australia	Prospective observational study	204			To evaluate the comorbidity Axis I; follow up study (2 years),	LAGB		39.7% Axis I, Mood disorders 26.5%, Anxiety disorders 15.2%, BED 13.2%. After surgery: Axis I 20%.
Lin HY et al. 2013 [37]	Taiwan	Retrospective study	841		M/F	Patients 2007-2010	Bariatric surgery vs Non-surgical	Taiwanese Depression Questionnaire (TDQ); Chinese Health Questionnaire (CHQ), SCID	42% mental disorders, mood disorders 27% in surgical group.
Mitchell et al. 2012 [103]	Pittsburgh (USA)	Retrospective study	199	46	M/F	Current and lifetime Axis I disorders	LAGB, RYGB	Longitudinal Assessment of bariatric Surgery	MDD lifetime 38.7%, MDD current 7%.
Hayden MJ et al., 2012 [33]	Melbourne (Australia)	Observational study	201			Evaluate BDI validity in obese patients	Candidates to surgery	SCID-I, BDI-I, BDI IA	26.9% (54) Mood Disorders, 37 MDD.
Alciati A. et al. 2011 [105]	Milan (Italy)	Retrospective study	120	44.4 ± 10.7 (bipolar spectrum); 41.6 ± 10.9 (no psychiatric disorders)	17m/55 F (bipolar spectrum	To evaluate the rate of childhood parental loss and relation with bipolar spectrum	Candidates to surgery	SCID-CV semi-structured interview related to childhood parental loss	91.7% had a bipolar spectrum disorder; 28% reported a childhood parental loss, more frequent in BD II.
Abiles V et al. 2010 [106]	Granada (Spain)	Observational study	50 patients (26 type III Obesity, 24 type IV Obesity) and 25 normal-weight controls	O-IV 38.54; O-III 39.31; CN 40.72	M/F	To analyze the psychopathological characteristics of obese candidates for bariatric surgery	Candidates to surgery	General Health Questionnaire, Rosenberg Self-Esteem Scale, Apgar Family Function Questionnaire, Spanish version of the Quality of Life Index, Eysenck Personality Questionnaire-Revised, Food Craving Questionnaire-Trait, Eating Disorders Examination-Questionnaire Version-4	The depression score significantly differed among groups, with the O-III and O-IV groups showing the highest values.
Muhlhans et al. 2009 [17]	Erlangen (Germany)	Observational study	145	38.6 for F; 39.1 for M	M/F (146)	To investigate the prevalence of Axis I psychopathology in bariatric surgery candidates	Candidates to surgery	Structured Clinical Interview for DSM-IV (SCID); Eating Disorder Examination (EDE)	Lifetime MDD 50.7%, current MDD 25.3%.
Mauri et al. 2008[16]	Pisa (Italy)	Observational study	282		M/F	Prevalence Axis I-II and QoL	Candidates to surgery	SCID I-II, Ham-D Bulimic Investigatory Test, short-form Quality of Life Enjoyment and Satisfaction Questionnaire	Lifetime Axis I 37.6%; Mood Disorders lifetime 22.0%, current MDD 4.5%. QoL significantly more impaired in patients with comorbid Axis I.
Wildes JE et al. 2008 [107]	Pittsburgh (USA)	Retrospective study	230			Childhood maltreatment and Axis I diagnosis	Candidates to surgery	Childhood Trauma Questionnaire, short form; SCID-I	66% history of childhood maltreatment; elevated rates of both unipolar and bipolar mood disorders.
Kalarchian et al. 2007 [15]		Observational study	288			Prevalence psychiatric disorders	Candidates to surgery		Lifetime psychiatric disorders (66.3%); Bipolar Disorder 1.4%.
Alciati et al. 2007 [12]	Milan (Italy)	Retrospective study	83	44.4 ± 10.7	M/F	To investigate the prevalence of bipolar spectrum (including sybsyndromal hypomania) in patients seeking surgical treatment).	Candidates to surgery	SCID-CV questionnaire; Hypomania Symptom Check list (HCL-32)	Bipolar spectrum disorder 89% of the sample, highest prevalence BD -II, comorbidity with panic disorder 30%.
Rosenburger PH et al. 2006 [14]	New Haven (USA)	Retrospective study	174			Current and lifetime psychiatric disorders and association with eating disorders	Candidates to surgery	SCID-I	MDD 14.9% (Lifetime), 3.4% (Current).
Sanchez-Romàn S. et al. 2003 [27]	Mexico	Retrospective study	70	49 +/-10.4	25 M, 35 F		Candidates to surgery	SCID-I	60% Axis I disorder, most frequent anxiety disorders and mood disorders.

F: Female; M: Male; RYGB: Roux-Y-Gastric Bypass; LAGB: Laparoscopic Adjustable Gastric Banding; MDD: Major Depressive Disorder; BD: Bipolar Disorder; BED: Binge Eating Disorder; SCID-I: Structured Clinical Interview for DSM IV Axis I disorders; Ham-D: Hamilton Rating Scale for Depression; BDI: Beck Depression Inventory; Beck Depression Inventory-II (BDI-II); QoL: Quality of Life