are only weakly related to tobacco use disorder. 
Functional Consequences of Tobacco Use Disorder
Medical consequences of tobacco use often be gin when tobacco users are in their 40s and
usually become progressively more debilitat ing over time. One-half of smokers who do
not stop using tobacco will die early from a tobacco-related illness, and smoking-related
morbidity occurs in more than one-half of tobacco users. Most medical conditions result
from exposure to carbon monoxide, tars, an d other non-nicotine components of tobacco.
The major predictor of reversibility is duration of smoking. Secondhand smoke increases
the risk of heart disease and cancer by 30%. Long-term use of nicotine medications does
not appear to cause medical harm. 
Comorbidity
The most common medical diseases from smoking are cardiovascular illnesses, chronic
obstructive pulmonary disease, and cancers. Smoking also increases perinatal problems,
such as low birth weight and miscarriage. Th e most common psychiat ric comorbidities are
alcohol/substance, depressive, bipolar, anxiet y, personality, and attention-deficit/hyper-
activity disorders. In individuals with curren t tobacco use disorder, the prevalence of cur-
rent alcohol, drug, anxiety, depressive, bi polar, and personality disorders ranges from
22% to 32%. Nicotine-dependent smokers are 2.7–8.1 times more likely to have these dis-
orders than nondependent smokers, never-smokers, or ex-smokers.