To the Editor: There is relatively little information about the long-term cognitive effects of long-term, recreational gasoline inhalation among functional subjects who are still residing in their communities (1). We present a case of severe cognitive impairment secondary to long-term gasoline inhalation with a background of low intellect.
Mr. A, a 19-year-old man, was seen for the second time with psychosis and bizarre behavior secondary to long-term gasoline inhalation over the last 2 years. To enhance the effects, he would heat the gasoline container under a hot water tap or in the oven and would add washing detergent and medicines, hoping to get an extra "high" from sniffing this concoction.
Mr. A had a developmental delay in childhood, especially in gross motor and language skills. School reports reflected that very poor performance and polysubstance abuse were prominent from his teenage years. Cognitive testing at age 16, before recreational gasoline inhalation, demonstrated global impairments and placed him within the mildly mentally deficient category on the Wechsler Intelligence Scale for Children (WISC-III). A second cognitive assessment on the Wechsler Adult Intelligence Scale (WAIS-III) (2) was administered during this admission. The results he obtained on the verbal, performance, and full-scale IQ all fell within the extremely low category of cognitive functioning. It was clear that there had been a considerable decrease in intellectual functioning since the first assessment.
Since there was no obvious structural brain deficit, a single photon emission computed tomography (SPECT) scan was performed to ascertain whether there was functional impairment. It showed a global decrease in brain activity, especially in the frontal lobes. The anterior edge had such low activity that on a coronal section, they were markedly flattened, with a "Swiss cheese" appearance. This finding was consistent with the poor executive functioning exhibited on the WAIS-III. There was also decreased activity in the inferior orbital lobes, the temporal lobes, and the cerebellum. It is unclear to what extent the SPECT scan abnormalities were related to the developmental delay in childhood or the effects of long-term gasoline inhalation. However, with the extent of frontal lobe functional impairment, it is likely that this was significantly worsened by gasoline inhalation abuse. This might explain the poor impulse control and judgment, which worsened Mr. A’s addiction to gasoline inhalation. Gasoline inhalation continues to perpetuate frontal lobe damage, creating a vicious cycle of increasing addiction and brain damage.
A magnetic resonance imaging scan would likely provide only equivocal information on the extent of brain damage because brain mass remains constant, despite the continued loss of brain functional capacity. The SPECT scan was useful for outlining the functional capacity of the brain and might be a useful adjunct in the future for assessing brain impairment from substance inhalation.