Reliable change indices for 16 neuropsychological tests at six different time points

Area of Science:

• Neuropsychology
• Cognitive Science
• Psychometrics

Background:

• Repeated neuropsychological testing is crucial for assessing cognitive change and longitudinal patient follow-up.
• Interpreting score changes requires reliable longitudinal reference data.
• Current methods may be subject to biases from successive assessments.

Purpose of the Study:

• To provide reference data for interpreting score changes in 16 common neuropsychological tests.
• To establish reliable change indices across six different time intervals between assessments.
• To enable accurate assessment of cognitive change in longitudinal studies.

Main Methods:

• Longitudinal analysis of data from the Normacog project involving 388 healthy Spanish participants (aged 18-84).
• Two assessment occasions with follow-up intervals of 1, 3, 6, 9, 12, or 24 months.
• Calculation of five reliable change indices, including discrepancy scores, standard deviation index (SDI), and reliable change index (RCI).

Main Results:

• Significant improvements in assessment scores were observed across all time points, particularly in memory-related variables.
• Reference data were generated using discrepancy scores (percentiles), SDI, RCI, RCI with practice effect (RCI+PE), and standardized regression-based formulae.
• The provided data facilitate the objective interpretation of cognitive score fluctuations.

Conclusions:

• The study offers essential data for determining the reliability of observed cognitive changes.
• Reliable change indices are supported as a method to mitigate biases associated with repeated testing.
• This research establishes a foundation for clinical implementation and the development of future reliable change indices.