People living with psychotic illness 2010

Appendix 9. Cognition

Page last updated: November 2011

Two short cognitive tests of five minutes each were selected to assess general cognitive ability. Both tests are widely used with people with a psychotic disorder.

The Digit Symbol Coding test from the Repeatable Battery for the Assessment of Neuropsychological Status was used to assess current general cognitive ability.20 The population comparison came from Australian Schizophrenia Research Bank general population data.21

The National Adult Reading Test-Revised14 was used to estimate general cognitive ability prior to illness onset. Only the predicted full scale IQ score was included in this report. The population comparison came from National Adult Reading Test-Revised standardised norms.

There were 1,619 participants (88.7%) with valid Digit Symbol Coding test data and 1,546 participants (84.7%) with valid National Adult Reading Test-Revised data.

Participants had a mean Digit Symbol Coding test score of 38.6 (standard deviation 10.7) compared to a population average of 54.2 (standard deviation, 9.8).

The mean National Adult Reading Test-Revised score was 98.1 (standard deviation, 11.3) for participants compared to a population average of 107.4 (standard deviation, 17.1).