A comparative neuropsychological test battery differentiates cognitive signatures of Fragile X and Down syndrome.
BACKGROUND
Standardised neuropsychological and cognitive measures present some limitations in their applicability and generalisability to individuals with intellectual disability (ID). Alternative approaches to defining the cognitive signatures of various forms of ID are needed to advance our understanding of the profiles of strengths and weaknesses as well as the affected brain areas.


OBJECTIVE
To evaluate the utility and feasibility of six non-verbal comparative neuropsychological (CN) tasks administered in a modified version of the Wisconsin General Test Apparatus (WGTA) to confirm and extend our knowledge of unique cognitive signatures of Fragile X syndrome (FXS) and Down syndrome (DS).


METHODS
A test battery of CN tasks adapted from the animal literature was administered in a modified WGTA. Tasks were selected that have established or emerging brain-behaviour relationships in the domains of visual-perceptual, visual-spatial, working memory and inhibition.


RESULTS
Despite the fact that these tasks revealed cognitive signatures for the two ID groups, only some hypotheses were supported. Results suggest that whereas individuals with DS were relatively impaired on visual-perceptual and visual-spatial reversal learning tasks they showed strengths in egocentric spatial learning and object discrimination tasks. Individuals with FXS were relatively impaired on object discrimination learning and reversal tasks, which was attributable to side preferences. In contrast, these same individuals exhibited strengths in egocentric spatial learning and reversal tasks as well as on an object recognition memory task. Both ID groups demonstrated relatively poor performance for a visual-spatial working memory task.


CONCLUSIONS
Performance on the modified WGTA tasks differentiated cognitive signatures between two of the most common forms of ID. Results are discussed in the context of the literature on the cognitive and neurobiological features of FXS and DS.
Kogan
C S
CS
School of Psychology, University of Ottawa, Ottawa, ON, Canada. ckogan@uottawa.ca
Boutet
I
I
Cornish
K
K
Graham
G E
GE
Berry-Kravis
E
E
Drouin
A
A
Milgram
N W
NW
D000293:Adolescent; D000328:Adult; D002170:Canada; D002648:Child; D003071:Cognition; D003937:Diagnosis, Differential; D004192:Discrimination, Psychological; D004314:Down Syndrome / Q000175:diagnosis* / Q000523:psychology; D005240:Feasibility Studies; D005600:Fragile X Syndrome / Q000175:diagnosis* / Q000523:psychology; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008570:Memory, Short-Term; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D021641:Recognition, Psychology; D012193:Reversal Learning; D013028:Space Perception; D013647:Task Performance and Analysis; D014796:Visual Perception; D055815:Young Adult