The term “fragile X syndrome” is named after a constriction recognizable on chromosome (at Xq 27.3) cultured at chromosome media without folic acid. The unstable part includes repetition of 3 nucleotides which is intensified at subsequent generation (DNA amplification) and gives rise to a more severe phenotype in the individual. About 20% of males have normal fragile X syndrome. The daughters of these individuals have abnormal chromosomes (carrier) and their grandchildren will be marked. In typical syndrome, the boys will suffer from mental retardation, macrocephalia, large or protruding ears, elongated face, and macroorchidism.

In terms of behavioral comorbidity, symptoms are similar to pervasive developmental disorder such as autism and attention deficit/hyperactivity disorder. The impairments in cognitive abilities are manifested as learning difficulties to severe problems.

Our patients were 2 boys (6 and 7 years old) referred due to their hyperactivity. In physical examination, attention deficit/hyperactivity disorder as well as fragile X syndrome were confirmed. In chromosome culture test, the constriction at Xq 27.3 was specified.

Objective: The present study aimed to determine the effectiveness of response inhibitation training on working memory in male students with attention deficit/ hyperactivity disorder.

Materials & Methods: The present research was a quasi-experimental study by pre-test, post-test design with control group. Forty male students with attention deficit/ hyperactivity disorder (8 to 10 years old) were selected by convenient sampling method from schools of Varamin and Gharchak province. They were divided into experimental and control group (each consists of 20 individuals) randomly and equally. The experimental group participated in response inhibitation training in 10 sessions (two sessions weekly each lasts for 60 minutes), while control group did not. Cornoldy Working Memory Test were used for assessment of all participants. Data were analyzed by analysis of covariance through SPSS version 16.

Results: Findings showed that response inhibitation training had positive and significant effect on the working memory of students with attention deficit/ hyperactivity disorder (P<0.001).

Conclusion: The results indicated that response inhibitation training program has led to the improvement of working memory of male students with attention deficit/ hyperactivity disorder. It is suggested that specialists with planing and implementation of response inhibitation training program promoted working memory of students with attention deficit/ hyperactivity disorder.