Smoking Cessation and the Risk of Hyperactive Delirium in Hospitalized Patients: A Retrospective Study

Objectives: The acute cessation of smoking often induces symptoms that are similar to those associated with delirium. We aimed to evaluate effects of sudden nicotine abstinence on the development of delirium and its motoric subtypes in hospitalized patients. Methods: The present study included patients who were referred to psychiatrists by ward physicians due to confusion. The presence of delirium was defined using the Confusion Assessment Method and the Delirium Rating Scale Revised–98, which was also used to assess the severity of delirium. Outcome variables, including the length of hospital stay and 3-month mortality rate, were collected by a retrospective chart review. Results: Delirium was confirmed in 210 of the 293 referred patients. Of the motoric subtypes of delirium, the hyperactive subtype was more common (68.1%) and was related to higher 3-month mortality (odds ratio [OR], 2.189; 95% confidence interval [CI], 1.07 to 4.49; P = 0.033) compared with hypoactive delirium. Patients undergoing sudden cessation of smoking (n = 55) were more likely to exhibit hyperactive delirium than were nonsmokers (P = 0.001). A multivariate analysis revealed that smoking cessation was an independent risk factor for hyperactive delirium (OR, 10.33; 95% CI, 2.31 to 46.09; P = 0.002). In addition, the amount of smoking was positively correlated with the severity of hyperactivity (r = 0.421, P = 0.003). Smoking status did not significantly influence overall delirium incidence. Conclusions: The present findings demonstrated that nicotine withdrawal was associated with hyperactive delirium, which suggests that they share common pathophysiologies that involve the dopamine, opioid, and cholinergic systems.