title: Predicting conversion to dementia in a memory clinic: A standard clinical approach compared with an empirically defined clustering method (latent profile analysis) for mild cognitive impairment subtyping.
abstract: BACKGROUND
  Mild cognitive impairment (MCI) has clinical value in its ability to predict later dementia. A better understanding of cognitive profiles can further help delineate who is most at risk of conversion to dementia. We aimed to (1) examine to what extent the usual MCI subtyping using core criteria corresponds to empirically defined clusters of patients (latent profile analysis [LPA] of continuous neuropsychological data) and (2) compare the two methods of subtyping memory clinic participants in their prediction of conversion to dementia.
  
  
  METHODS
  Memory clinic participants (MCI, n = 139) and age-matched controls (n = 98) were recruited. Participants had a full cognitive assessment, and results were grouped (1) according to traditional MCI subtypes and (2) using LPA. MCI participants were followed over approximately 2 years after their initial assessment to monitor for conversion to dementia.
  
  
  RESULTS
  Groups were well matched for age and education. Controls performed significantly better than MCI participants on all cognitive measures. With the traditional analysis, most MCI participants were in the amnestic multidomain subgroup (46.8%) and this group was most at risk of conversion to dementia (63%). From the LPA, a three-profile solution fit the data best. Profile 3 was the largest group (40.3%), the most cognitively impaired, and most at risk of conversion to dementia (68% of the group).
  
  
  CONCLUSIONS
  LPA provides a useful adjunct in delineating MCI participants most at risk of conversion to dementia and adds confidence to standard categories of clinical inference.
authors.affiliation: Centre for Public Health, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: Bernadette
authors.initials: B
authors.lastname: McGuinness
authors.affiliation: School of Psychology, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Barrett
authors.affiliation: Centre for Public Health, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: John
authors.initials: J
authors.lastname: McIlvenna
authors.affiliation: Centre for Public Health, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland.
authors.forename: Anthony Peter
authors.initials: AP
authors.lastname: Passmore
authors.affiliation: National Institute for Mental Health Research, Australian National University, Canberra, ACT, Australia; All Ireland Hub for Trials Methodology Research, Ulster University, Londonderry, Northern Ireland.
authors.forename: Gillian W
authors.initials: GW
authors.lastname: Shorter
keywords: Alzheimer's disease; Cognitive profiles; Latent profile analysis; Longitudinal study; Mild cognitive impairment