A neuropsychological and behavioural profile of attention deficits in fragile X syndrome

Cornish K, Munir F, Wilding J.

Section of Developmental Psychiatry, Divisiono f Psychiatry, University of Nottingham, Jubilee Campus, Nottingham, United Kingdom.

INTRODUCTION: Fragile X syndrome is a well-recognised cause of developmental delay in males and to a lesser extent females. The aim of the present study was to present a detailed cognitive and behaviour analysis of the core attention impairments frequently associated with fragile X. PATIENTS AND METHODS: Two complementary studies were conducted. Study 1 examined the severity and range of behavioural problems in a group of 25 fragile X boys with fragile X compared with five control groups: a learning disabled comparison group (Down's syndrome-Trisomy 21) and four groups of normal developing control children. Two well validated rating scales were used as measures of behaviour: Study 2 examined performance by the above groups on a novel computerised task of attention that measured the ability to inhibit irrelevant responses. RESULTS: Findings from Study 1 revealed that fragile X children were significantly more hyperactive, inattentive and impulsive in comparison with the Down's syndrome children but not in comparison to the poor attention control groups. The findings from Study 2 revealed that the main impairment in fragile X was in inhibiting repetition of successful responses and in switching attention from one type of response to another in a sequence, whether it has been successful or not. CONCLUSION: Emerging evidence now supports the hypothesis that the fundamental deficit in fragile X is in controlling the flow of sequences of input and output. It is suggested that this control require inhibition.