Table 1.

General characteristics of subjects

¹⁾Mean ± SD

²⁾Not Significant

³⁾Values with different superscripts within a row are significantly different at a=0.05 as determined by Duncan's multiple range test.

⁴⁾The sum of the number of cigarettes smoked per day in each year of life up until the time of the scan, divided by 20, the number of cigarettes in a packet