Tobacco and cognitive performance in schizophrenia patients: the design of the COGNICO study

People with schizophrenia constitute a substantial part of the people who still smoke. Regarding cognitive performance, the self-medication hypothesis states that patients smoke to improve their cognitive deficits based on the stimulating effects of nicotine. The aim of this paper is to describe in detail the methodology used in the COGNICO study. A quasi-experimental, observational, prospective, multicenter study with follow-ups over 18 months was conducted in three cities in northern Spain (Oviedo, Ourense and Santiago de Compostela). A total of 81 outpatient smokers with schizophrenia were recruited with a mean age 43.35 years (SD = 8.83), 72.8% of them male. They were assigned to 3 groups: a) control group (smokers); b) patients who quit smoking using nicotine patches; c) patients who quit smoking with Varenicline. The MATRICS neuropsychological battery was applied as a primary measure. In addition, a comprehensive assessment of patients was performed, including the number of cigarettes per day, physical and psychological dependence on nicotine and CO expired. Clinical evaluation (PANSS, HDRS, CGI, C-SSRS), anthropometric measurements and vital signs assessment was also performed. The aim is to identify the relationship between the pattern of tobacco use and cognitive performance by comparing scores on the neuropsychological battery MATRICS during the follow-up periods (3, 6, 12 and 18months). The importance of this study lies in addressing a topical issue often ignored by clinicians: the unacceptably high rates of tobacco use in patients with severe mental disorders.