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5 April 2018

Comparing visuospatial associative learning for a middle-aged birth cohort and patients with schizophrenia

Visuospatial memory is extremely heterogeneous in schizophrenia. In a large population study, around a fifth of patients with schizophrenia showed similar errors rates to the top 50% of the general population. Conversely, half of the patients sampled showed substantial impairments. 

Background

  • In the general population, visuospatial associative learning can start to decline from the age of 40.
  • Previous studies have shown that this cognitive function is substantially impaired in many patients with schizophrenia.
  • Scientists at Cambridge Cognition compared visuospatial memory for middle-aged, typically-developing adults and patients with schizophrenia.

 

Methods

  • The study included a total of >5000 participants drawn from the:
    • Northern Finland Birth Cohort 1966 (NFBC66), a general population sample.
    • Finnish SUPER study of schizophrenia, part of the Stanley Global Neuropsychiatric Genomics Initiative.
  • Visuospatial memory was assessed using the CANTAB Paired Associative Learning (PAL) Test, as shown in figure 1. The primary outcome variables were:
    • ‘Total errors adjusted’ (TEA): the total number of times the participant selected the incorrect box, adjusted for trials not completed due to early termination.
    • ‘First attempt memory score’ (FAMS): the total number of correct choices made by the participant on the first attempt of the trials.

 

Results

  • Compared with the general population, the SUPER sample of patients with schizophrenia made less than half as many correct first choices (FAMS) on average.
  • This pattern was mirrored in TEA. On average, the SUPER sample made more than twice as many errors (TEA) than the general population.
  • However, the distribution of scores was very different between the two groups, as visualized in figure 2.

 

Discussion

  • Visual memory is extremely heterogeneous in schizophrenia. Performance is characterized by a multimodal distribution which is not seen in the general population.
  • Around a fifth of patients with schizophrenia had error scores similar to the top 50% of the general population, while around half showed a substantial impairment.

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Tags : schizophrenia | birth cohort | pal | cias | visuospatial memory

Author portrait

Dr Jenny Barnett, CSO