Among the total of 159 participants, ICAM-1 mRNA levels in PBMCs positively correlated with the gender, number of cigarettes smoked per day (p < 0.0001), smoking index (p < 0.0001), smoking duration (p < 0.0001), level of nicotine dependence (p < 0.0001), and the presence of cardiovascular diseases (p = 0.0313) (Table 3). Here, ICAM1 is linked to nicotine dependence.