Relationship between intelligence quotient (IQ) and cerebral metabolic rate of oxygen in patients with neurobehavioural disability after traumatic brain injury.

ABSTRACT

OBJECTIVE: Cerebral metabolism may play a significant role in neurobehavioural disability following traumatic brain injury (TBI). In this study, we examined the relationship between intelligence quotient (IQ) and the cerebral metabolic rate of oxygen (CMRO2) in the lateral prefrontal cortex, which was measured by 15O-labelled gas positron emission tomography (PET), in patients with TBI. MATERIALS AND METHODS: The subjects were 12 patients (eight males and four females) who suffered from neurobehavioural disability following TBI. Their mean age was 33.3 years. The cause of injury was traffic accidents in all patients and the mean period after injury was 44.8 months. These patients underwent 15O-labelled gas PET and tests using either the Wechsler Adult Intelligence Scale-Revised (WAIS-R) or the Wechsler Intelligence Scale for Children-Revised (WISC-R). Pearson's correlation between CMRO2 and total IQ (TIQ) was calculated. RESULTS: A statistically significant correlation was observed between TIQ and CMRO2 in the right Brodmann areas (BAs) 44 and 45. The lower the WAIS score, the higher the CMRO2 in both areas. CONCLUSION: Neurological function negatively correlated with the metabolism of oxygen. It was possible that changes in brain networks increased the neuronal activity in the undamaged areas and that the increased activity compensated for the function decline.