Visuospatial Working Memory in School-aged Children Exposed In Utero to Cocaine

Abstract

Objective: Among the neurocognitive impairments reported as associated with prenatal cocaine exposure, slower response time, and less efficient learning in school-aged children are common to findings from several laboratories. This study presents performance data on a spatial working memory task in 75 prenatally cocaine exposed (CE) and 55 nondrug-exposed (NDE) 8- to 10-year-old children.

Methods: Children were administered a novel neuropsychological measure of immediate- and short-term memory for visuospatial information, the Groton Maze Learning Test^© (GMLT), a computer-based hidden maze learning test that consists of a “timed chase test” (a simple measure of visuomotor speed), eight learning trials followed by a delayed recall trial after an 8-minute delay and a reverse learning trial. Performance is expressed as correct moves per second and number of errors per trial.

Results: Across all trials, the cocaine-exposed group showed significantly slower correct moves per second and made significantly more errors. There were no significant main effects for amounts of alcohol, tobacco, or marijuana exposure. After an 8-minute delay and compared to the eighth trial, cocaine-exposed children showed less consolidation in learning compared to nonexposed children. When asked to complete the maze in reverse, cocaine-exposed children showed a greater decrement in performance (decreased correct moves per second and increased errors) compared to the eighth learning trial.

Conclusions: Children exposed in utero to cocaine exhibit a possible impairment in procedural learning and diminished efficiency in creating and accessing an internal spatial map to master the hidden maze.

Keywords:

• prenatal cocaine exposure
• visuospatial working memory
• delayed recall
• spatial map

This work was supported by several agencies that included NIDA grants RO1-DA-06025 (LCM), DA-017863 (LCM) and KO5 (LCM) and grants from NICHD P01-HD03008 and an unrestricted educational grant from Pfizer Inc. Additionally, the work was supported in part by the Yale Children's Clinical Research Center grant MO1-RR06022, General Clinical Research Centers Program, National Center for Research Resources, NIH. The authors gratefully acknowledge the database management support of Ireneusz Sielski and our close collaboration with Dr. Richard Schottenfeld and his substance abuse treatment programs for pregnant cocaine-using women. Many of the women in our studies were active participants in his studies and much of our information regarding their perinatal drug use was obtained through our collaboration with Dr. Schottenfeld.

Notes

¹For more information about the GMLT, please contact Dr. P. J. Snyder by E-mail: [email protected]; the GMLT is available for use from CogState, Ltd. (www.cogState.com).