title: Modification by two genes of associations between general somatic health and incident depressive syndrome in older people.
abstract: OBJECTIVE
  To investigate the modifying effects of two candidate genes (serotonin transporter gene linked promoter region (5-HTTLPR) and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms) on the associations between general somatic morbidity and incidence of depression in an East Asian population with high frequencies of potential risk alleles.
  
  
  METHODS
  With a 2-year prospective study of a community sample (N = 521) of older people (aged 65+), information on baseline number of health complaints, diagnosis of moderate/severe depressive syndrome (Geriatric Mental State), and genotypes for 5-HTTLPR and MTHFR C677T polymorphisms were ascertained. Interactions between somatic morbidity and the two genotypes were investigated for incident depression.
  
  
  RESULTS
  Incident depression was present in 63 (12%) and was associated with worse somatic health. Significant interactions between number of somatic complaints and both genotypes were observed. For the 5-HTTLPR genotypes, the association between the number of somatic disorders and depression was significant in s/s homozygotes (chi2 = 8.80 (1 df), p = .003) but not in heterozygotes (chi2 = 0.23, p = .634) or l/l homozygotes (chi2 = 0.04, p = .840). For the MTHFR genotypes, the association between the number of somatic disorders and depression was significant in T/T homozygotes (chi2 = 4.97, p = .026) but not in C/T heterozygotes (chi2 = 1.24, p = .265) or C/C homozygotes (chi2 = 1.04, p = .307).
  
  
  CONCLUSIONS
  These findings suggest that associations between general somatic morbidity and late-life depression are modified by at least two genes, and that elders with particular genotypes are at greater risk for onset of depression in the presence of somatic ill health.
authors.affiliation: Department of Psychiatry and Depression Clinical Research Center, Chonnam National University Medical School, Kwangju, Republic of Korea.
authors.forename: Jae-Min
authors.initials: JM
authors.lastname: Kim
authors.forename: Robert
authors.initials: R
authors.lastname: Stewart
authors.forename: Sung-Wan
authors.initials: SW
authors.lastname: Kim
authors.forename: Su-Jin
authors.initials: SJ
authors.lastname: Yang
authors.forename: Il-Seon
authors.initials: IS
authors.lastname: Shin
authors.forename: Jin-Sang
authors.initials: JS
authors.lastname: Yoon
mesh_terms: D000368:Aged; D002908:Chronic Disease; D017931:DNA Primers / Q000235:genetics; D003866:Depressive Disorder / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D005492:Folic Acid / Q000031:analogs & derivatives* / Q000235:genetics; D005838:Genotype; D006304:Health Status; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics*; D011446:Prospective Studies; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D012720:Severity of Illness Index; D013001:Somatoform Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D013577:Syndrome
chemical_list: D017931:DNA Primers; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; C032418:5,11-methenyltetrahydrohomofolate; D005492:Folic Acid