Have we failed to detect some withdrawal symptoms?
Thirty years ago, a list of signs and symptoms of tobacco withdrawal were derived from experimental studies. Amazingly, since then not a single new symptom has been included in the DSM or most other definitions of withdrawal. How likely is it that the scientists got it exactly right back then? In fact, several new symptoms to include have been suggested. The two with probably the most data are anhedonia (decrease in pleasure or interest in rewards) and impulsivity. A well‐done recent clinical study (Cook et al, Jl Abnormal Psychology 124:215) found that smoking cessation decreased reported pleasure from recreational, social and accomplishment rewards. This effect began on the first day and lasted about 4 days. The increase was about the same magnitude as other withdrawal symptoms and did predict inability to stop smoking. Since we now know nicotine increases the rewarding effects of non‐drug rewards, it makes sense that stopping smoking would decrease pleasure. In addition, anhedonia‐like effects with nicotine abstinence have been found in animals. Plus, anhedonia is closely associated with depression, an already recognized withdrawal symptom. The other likely new symptom is impulsivity. A recent meta‐analysis (Hughes et al, Nicotine Tobacco Research, epub ahead of print), found a consistent increase in ratings of impatience during experimental studies in humans. This review also noted that some, but not all, studies suggested abstinence increases delay discounting (i.e. made smokers value smaller, more immediate monetary rewards over larger delayed rewards) and decreases response inhibition (e.g. as seen in those with ADD). Although none of the studies reported whether impatience predicted problems quitting, one would think that increased impulsivity would undermine resolve to quit. Other candidate symptoms with less evidence include drowsiness, mood swings, decreased positive affect, cold symptoms, constipation, cough, and dizziness. Email if you want info on these.