ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effects of mild head injury (HI) on the victims'intelligence by measuring their intelligence quotient (IQ).</p><p><b>METHODS</b>This cohort study was performed in Khatam-ol-Anbia Hospital, Zahedan, Iran and the IQs of 30 mild HI patients were measured right after the injury (IQ0) and six months later (IQ6). The IQs of 90 close relatives of the patients were also measured at the same period of time as the non-exposure group. The IQs were measured with Wechsler adult intelligence scale-revised (WAIS-R). The IQ0, IQ6 and their differences (IQ change) were compared in HI patients and their relatives using the Student's t test.</p><p><b>RESULTS</b>The mean IQ0 of the HI patients was similar to their relatives. The IQ6 of HI patients appeared to be less than those of their relatives. Moreover, the IQ6 of the HI patients appeared to be less than their initial scores. HI was associated with more decrease in IQ6 compared with IQ0 and the female subjects showed more decrease in IQ6 compared with their IQ0.</p><p><b>CONCLUSION</b>HI seems to be associated with decrease in IQ six months after the injury and it is more evident in female HI patients.</p>