Visual memory profile in 22q11.2 microdeletion syndrome: are there differences in performance and neurobiological substrates between tasks linked to ventral and dorsal visual brain structures? A cross-sectional and longitudinal study

BACKGROUND: Children affected by the 22q11.2 deletion syndrome (22q11.2DS) have a specific neuropsychological profile with strengths and weaknesses in several cognitive domains. Specifically, previous evidence has shown that patients with 22q11.2DS have more difficulties memorizing faces and visual-object characteristics of stimuli. In contrast, they have better performance in visuo-spatial memory tasks. The first focus of this study was to replicate these results in a larger sample of patients affected with 22q11.2DS and using a range of memory tasks. Moreover, we analyzed if the deficits were related to brain morphology in the structures typically underlying these abilities (ventral and dorsal visual streams). Finally, since the longitudinal development of visual memory is not clearly characterized in 22q11.2DS, we investigated its evolution from childhood to adolescence. METHODS: Seventy-one patients with 22q11.2DS and 49 control individuals aged between 9 and 16 years completed the Benton Visual Retention Test (BVRT) and specific subtests assessing visual memory from the Children’s Memory Scale (CMS). The BVRT was used to compute spatial and object memory errors. For the CMS, specific subtests were classified into ventral, dorsal, and mixed subtests. Longitudinal data were obtained from a subset of 26 patients and 22 control individuals. RESULTS: Cross-sectional results showed that patients with 22q11.2DS were impaired in all visual memory measures, with stronger deficits in visual-object memory and memory of faces, compared to visuo-spatial memory. No correlations between morphological brain impairments and visual memory were found in patients with 22q11.2DS. Longitudinal findings revealed that participants with 22q11.2DS made more object memory errors than spatial memory errors at baseline. This difference was no longer significant at follow-up. CONCLUSIONS: Individuals with 22q11.2DS have impairments in visual memory abilities, with more pronounced difficulties in memorizing faces and visual-object characteristics. From childhood to adolescence, the visual cognitive profile of patients with 22q11.2DS seems globally stable even though some processes show an evolution with time. We hope that our results will help clinicians and caregivers to better understand the memory difficulties of young individuals with 22q11.2DS. This has a particular importance at school to facilitate recommendations concerning intervention strategies for these young patients.