Neurobehavioral changes/neurological

Neurobehavioral changes were observed in rats (Clark and Pearson 1973) and mice (Clark et al. 1971) exposed orally for intermediate durations. Necrosis and atrophy of the optic nerve and retina in dogs (Uga et a1. 1977) were observed after oral exposure. Based on the results of the human and animal studies, neurological effects (subtle and/or overt) may occur regardless of the route of exposure. Additional animal studies do not seem to be warranted at this time. 

Neuropsychological procedures are used in an effort to provide an unbiased estimate of the individual s cognitive capacity. In neurology and psychiatry, these tests have been used to help clinicians to better diagnose patients and to provide them with better treatments. We chose to use a fixed battery in our effort to assess neurobehavioral changes that might be associated with the chronic use of marijuana. That battery included tests of language skills, visual and spatial memory, attention, concentration, executive function, visuo-constructive skills, manual dexterity, simple reaction time, and complex reaction time in subjects in our studies. The various tests used are listed below. 

Styrene exposures between 50 and 100 ppm have been associated with neurological effects including decrements in color discrimination, nerve conduction, and neurobehavioral performance. These changes appear to be transient, with improvement... 

In summary, the above studies show that neurobehavioral evaluation of pesticide workers reveal increased prevalence of neurologic symptoms and changes in neurobehavioral performance indicative of mild cognitive and psychomotor dysfunction. These effects appear to be more prevalent during the period of exposure, but also persist beyond the period of exposure. Total cumulative exposure seems to be a greater risk factor for poor performance than any other covariant. Deficits in visuomotor speed as indexed by the digit symbol substimtion test and the trailmaking tests have been shown to be consistently effected as well as tests of selective attention and memory... 

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