Temporal Stability of the Dutch Version of the Wechsler Memory Scale: Fourth Edition (WMS-IV-NL)

Objective: The Wechsler Memory Scale—Fourth Edition (WMS-IV) is one of the most widely used memory batteries. We examined the test–retest reliability, practice effects, and standardized regression-based (SRB) change norms for the Dutch version of the WMS-IV (WMS-IV-NL) after both short and long retest intervals. Method: The WMS-IV-NL was administered twice after either a short (M = 8.48 weeks, SD = 3.40 weeks, range = 3–16) or a long (M = 17.87 months, SD = 3.48, range = 12–24) retest interval in a sample of 234 healthy participants (M = 59.55 years, range = 16–90; 118 completed the Adult Battery; and 116 completed the Older Adult Battery). Results: The test–retest reliability estimates varied across indexes. They were adequate to good after a short retest interval (ranging from .74 to .86), with the exception of the Visual Working Memory Index (r = .59), yet generally lower after a long retest interval (ranging from .56 to .77). Practice effects were only observed after a short retest interval (overall group mean gains up to 11 points), whereas no significant change in performance was found after a long retest interval. Furthermore, practice effect-adjusted SRB change norms were calculated for all WMS-IV-NL index scores. Conclusions: Overall, this study shows that the test–retest reliability of the WMS-IV-NL varied across indexes. Practice effects were observed after a short retest interval, but no evidence was found for practice effects after a long retest interval from one to two years. Finally, the SRB change norms were provided for the WMS-IV-NL.