Inverted U shaped effect of nicotine on the severity of depressive symptoms: A population-based survey

To investigate whether that nicotine concentration represented by the degree of smoking dependence variably influence the rate and severity of depressive symptoms.Cross-sectional, analytical study, involving 300 medical students selected by random sampling techniques were asked to complete a questionnaire contains three parts: demographic information, Beck Depression Inventory with cutoff point for depression is 17 and the Fagerström Test for Nicotine dependence with cutoff point for severe dependence is five.A total of 233 medical students completed the questionnaire; their mean age was (21.38 ± 1.74). The rate of smoking was 22.7% while that of depression was 32.2%. Low dependent smokers in contrast to other groups of smokers and non-smokers display the lowest rate of depressive symptoms (15%), while the highest rate recorded among severely dependent smokers (71.4%, p = 0.0001). After adjustment of other risk factors, regression analysis reveal that severe dependent smokers associated with 12.5 odds of depressive symptoms than non-smokers (p = 0.0001, C.I. 4.10-38.29).In comparison with light and moderate smokers, heavy smokers demonstrate higher risk of depressive symptoms in medical students.