Introduction:
Oxidative stress is induced by tobacco smoking and is also associated with anxiety and depression, two common psychiatric disorders, frequently associated with tobacco use.

Aim:
The aim of this study was to correlate tobacco use and mixed anxious-depressive disorder with oxidative stress markers useful in clinical practice.

Material and Methods:
A study assessing uric acid, vitamin C and malondialdehyde, as oxidative stress markers, was conducted in 31 smokers versus non-smokers with mixed anxious-depressive disorder. Other useful parameters assessed were: serum cholesterol, triglycerides and creatinine. Smoking profile was quantified by the number of pack-years (PY) and the Fagerström nicotine dependence score (FNDS) with exhaled carbon monoxide (CO) validation, while mixed anxious-depressive disorder was certified by the Hamilton Anxiety/Depression Scale (HAM-A/D.)

Results:
In both smokers and non-smokers were found very high values of the HAM-A anxiety evaluation score (17–41) as well as for the HAM-D depression evaluation score (12–26), as most subjects were diagnosed with severe anxiety and moderate depression. Malondialdehyde (MDA), serum concentration was significantly increased in 73% of the smokers, while vitamin C was lower in 90% of both smoking and non-smoking patients. Lower concentrations of uric acid were found in smokers, suggesting a decreased endogenous production. The correlation matrix between the biochemical and the clinical parameters for the assessment of oxidative stress in smokers and non-smokers diagnosed with mixed anxious-depressive disorder had statistically significant correlation coefficients (r=0.39–0.84; p˂0.05), which could explain the variation in serum MDA and Vitamin C concentrations depending on the severity of the nicotine dependence.

Conslusions:
Tobacco smoking amplifies oxidative stress described in psychiatric disorders. Monitoring most important biomarkers of both tobacco exposure and of oxidative stress can improve mixed anxious-depressive disease management.