title: Association between hippocampal volume and P300 event related potential in psychosis: support for the Kraepelinian divide.
abstract: BACKGROUND
  Abnormalities of the P300 event related potential (ERP) and of hippocampal structure are observed in individuals with psychotic disorders and their unaffected relatives. The understanding and clinical management of psychotic disorders are largely based on the descriptive Kraepelinian distinction between 'dementia praecox' and 'manic depressive psychosis', and not dependant on any well demarcated biological underpinnings. The hippocampus is postulated to be one of the main P300 generators, yet it remains unknown whether hippocampal volume decrements are associated with P300 deficits in psychosis, and whether any association is shared across non-affective and affective psychotic disorders.
  
  
  METHODS
  228 subjects from the Maudsley Family Psychosis Study comprising 55 patients with non-affective psychosis, 23 patients with psychotic bipolar disorder, 98 unaffected relatives, and 52 unrelated controls contributed structural MRI and ERP data. To study the relationship between hippocampal volume and P300 ERP, a seemingly unrelated regression methodology was used, accounting for whole brain volumes, clinical groups, age and gender in the analysis.
  
  
  RESULTS
  An association between left hippocampal volume and P300 latency in the combined sample comprising non-affective and affective psychotic patients, their relatives and controls was observed. There was an inverse relationship between brain structure and function in that prolongation of P300 latencies was associated with smaller left hippocampal volumes. On subdividing the sample based on Kraepelinian dichotomy, this association remained significant only for the non-affective psychosis group, comprising patients and their unaffected relatives.
  
  
  CONCLUSIONS
  Based on our findings, P300 latency, a measure of the speed of neural transmission, appears to be related to the size of the left hippocampus in schizophrenia, but not in psychotic bipolar disorder. It seems that underlying neuro-biological characteristics could help in unravelling the traditional Kraepelinian differentiation between the two major psychoses. The specificity of this brain structure-function association for schizophrenia opens the scope for further research using integration of multimodal biological data for objective categorisation of psychosis.
authors.affiliation: NIHR Biomedical Research Centre, Institute of Psychiatry (King's College London)/South London and Maudsley NHS Foundation Trust, London, UK. Anirban.Dutt@kcl.ac.uk
authors.forename: Anirban
authors.initials: A
authors.lastname: Dutt
authors.forename: Taposhri
authors.initials: T
authors.lastname: Ganguly
authors.forename: Madiha
authors.initials: M
authors.lastname: Shaikh
authors.forename: Muriel
authors.initials: M
authors.lastname: Walshe
authors.forename: Katja
authors.initials: K
authors.lastname: Schulze
authors.forename: Nicolette
authors.initials: N
authors.lastname: Marshall
authors.forename: Miguel
authors.initials: M
authors.lastname: Constante
authors.forename: Colm
authors.initials: C
authors.lastname: McDonald
authors.forename: Robin M
authors.initials: RM
authors.lastname: Murray
authors.forename: Matthew P G
authors.initials: MP
authors.lastname: Allin
authors.forename: Elvira
authors.initials: E
authors.lastname: Bramon
mesh_terms: D000328:Adult; D000368:Aged; D004569:Electroencephalography / Q000379:methods*; D018913:Event-Related Potentials, P300; D005260:Female; D006624:Hippocampus / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011618:Psychotic Disorders / Q000473:pathology* / Q000503:physiopathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D055815:Young Adult