title: Association between subjective memory complaints and depressive symptoms after adjustment for genetic and family environmental factors in a Japanese twin study.
abstract: OBJECTIVE
  The aim of this study was to investigate the association between subjective memory complaints (SMCs) and depressive symptoms, with and without adjustment for genetic and family environmental factors.
  
  
  METHODS
  We conducted a cross-sectional study using twins and measured SMCs and depressive symptoms as outcomes and explanatory variables, respectively. First, we performed regression analyses using generalized estimating equations to investigate the associations between SMCs and depressive symptoms without adjustment for genetic and family environmental factors (individual-level analyses). We then performed regression analyses for within-pair differences using monozygotic (MZ) and dizygotic (DZ) twin pairs and MZ twin pairs to investigate these associations with adjustment for genetic and family environmental factors by subtracting the values of one twin from those of co-twin variables (within-pair level analyses). Therefore, differences between the associations at individual- and within-pair level analyses suggested confounding by genetic factors.
  
  
  RESULTS
  We included 556 twins aged ≥ 20 years. In the individual-level analyses, SMCs were significantly associated with depressive symptoms in both males and females [standardized coefficients: males, 0.23 (95% CI 0.08-0.38); females, 0.35 (95% CI 0.23-0.46)]. In the within-pair level analyses using MZ and same-sex DZ twin pairs, SMCs were significantly associated with depressive symptoms. In the within-pair level analyses using the MZ twin pairs, SMCs were significantly associated with depressive symptoms [standardized coefficients: males, 0.32 (95% CI 0.08-0.56); females, 0.24 (95% CI 0.13-0.42)].
  
  
  CONCLUSIONS
  This study suggested that SMCs were significantly associated with depressive symptoms after adjustment for genetic and family environmental factors.
authors.affiliation: Department of Health Promotion Science, Osaka University Graduate School of Medicine, Suita, Osaka, Japan. haruka.tanaka@mcn.ac.jp.|Mie Prefectural College of Nursing, 1-1-1 Yumegaoka, Tsu, Mie, 514-0116, Japan. haruka.tanaka@mcn.ac.jp.
authors.forename: Haruka
authors.initials: H
authors.lastname: Tanaka
authors.affiliation: Department of Health Promotion Science, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.|Japan Society for the Promotion of Science, Tokyo, Japan.
authors.forename: Soshiro
authors.initials: S
authors.lastname: Ogata
authors.affiliation: Mie Prefectural College of Nursing, 1-1-1 Yumegaoka, Tsu, Mie, 514-0116, Japan.
authors.forename: Kayoko
authors.initials: K
authors.lastname: Omura
authors.affiliation: Center for Twin Research, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Honda
authors.affiliation: Department of Health Promotion Science, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Kamide
authors.affiliation: Mie Prefectural College of Nursing, 1-1-1 Yumegaoka, Tsu, Mie, 514-0116, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Hayakawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D003863:Depression / Q000453:epidemiology* / Q000235:genetics; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008569:Memory Disorders / Q000453:epidemiology* / Q000235:genetics; D008875:Middle Aged; D012307:Risk Factors; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic; D055815:Young Adult
keywords: Depressive symptoms; Subjective memory complaints; Twin study