Non-invasive assessment of acute effects of cigarette smoking on cerebral circulation

The usefulness of sequential single photon emission computed tomograph technique using Tc-99m hexamethylpropyleneamine oxime was tested to assess the acute effects on cerebral circulation of cigarette smoking and other activation task. The evaluation of reproducibility, photo-stimulation study, and carbon dioxide inhalation study were carried out. In the subjects, who were examined for cerebral perfusion under the resting condition repeatedly, no significant perfusion changes were detected in visual analysis, in quantitative analysis, or in distribution change mapping. The significant increase of CBF in the occipital lobes was found by photo-stimulation. The CO2 reactivity, estimated by a pair of perfusion images obtained under normocapnia and hypercapnia, was lower in the affected side than in the non-affected side of the patients with unilateral major occlusive lesions in the carotid system. These results showed our method was applicable to assess acute effects on regional CBF of cigarette smoking. Five normal volunteers were investigated for the CBF response to cigarette smoking. Although localized CBF increases were detected in two cases, no characteristic pattern could be found. These results suggested that in normal subjects, the effects of cigarette smoking on regional cerebral circulation varied among individuals, depending on the pharmacological properties of the absorbed nicotine including different sensitivity of each subject to nicotine.