title: Evidence for a late onset bipolar-I disorder sub-group from 50 years.
abstract: BACKGROUND
  Age of onset has been used to identify aetiological sub-groups in complex inherited disorders such as Alzheimer's disease and osteoarthritis. We examined the relationship between age of onset and family history in bipolar-I disorder in an attempt to identify subgroups.
  
  
  METHODS
  All patients discharged from a district in-patient service diagnosed with bipolar disorder in a 7-year period were ascertained from a case register (n=277). Diagnosis by DSM-IIIR criteria was confirmed; family history and age of first admission were recorded from case notes.
  
  
  RESULTS
  Age of first admission in those with a negative family psychiatric history was significantly older (P=0.029) with a skewed age distribution. This non-familial group contained significantly more subjects with first admission from the age of 50 years (P=0.007).
  
  
  CONCLUSIONS
  Patients with bipolar-I disorder whose age of first admission is 50 years or above may belong to a different aetiological sub-group.
authors.affiliation: Department of Psychiatry, University of Newcastle upon Tyne, Royal Victoria Infirmary, Newcastle upon Tyne NE1 4LP, UK. s.r.j.moorhead@ncl.ac.uk
authors.forename: Stephen R J
authors.initials: SR
authors.lastname: Moorhead
authors.forename: Allan H
authors.initials: AH
authors.lastname: Young
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001714:Bipolar Disorder / Q000145:classification / Q000175:diagnosis* / Q000235:genetics / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004739:England; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010343:Patient Admission; D012306:Risk