Hippocampal volume and auditory attention on a verbal memory task with adult survivors of pediatric brain tumor.

Objective: We examined the nature of verbal memory deficits and the possible hippocampal underpinnings in long-term adult survivors of childhood brain tumor.

Method: 35 survivors (M = 24.10 ± 4.93 years at testing; 54% female), on average 15 years post-diagnosis, and 59 typically developing adults (M = 22.40 ± 4.35 years, 54% female) participated. Automated FMRIB Software Library (FSL) tools were used to measure hippocampal, putamen, and whole brain volumes. The California Verbal Learning Test-Second Edition (CVLT-II) was used to assess verbal memory.

Results: Hippocampal, F(1, 91) = 4.06, ηp² = .04; putamen, F(1, 91) = 11.18, ηp² = .11; and whole brain, F(1, 92) = 18.51, ηp² = .17, volumes were significantly lower for survivors than controls (p < .05). Hippocampus and putamen volumes were significantly correlated (r = .62, p < .001) with each other, but not with total brain volume (r = .09; r = .08), for survivors and controls. Verbal memory indices of auditory attention list span (Trial 1: F(1, 92) = 12.70, η² = .12) and final list learning (Trial 5: F(1, 92) = 6.01, η² = .06) were significantly lower for survivors (p < .05). Total hippocampal volume in survivors was significantly correlated (r = .43, p = .01) with auditory attention, but none of the other CVLT-II indices. Secondary analyses for the effect of treatment factors are presented.

Conclusion: Volumetric differences between survivors and controls exist for the whole brain and for subcortical structures on average 15 years post-diagnosis. Treatment factors seem to have a unique effect on subcortical structures. Memory differences between survivors and controls are largely contingent upon auditory attention list span. Only hippocampal volume is associated with the auditory attention list span component of verbal memory. These findings are particularly robust for survivors treated with radiation.