Nicotine consumption and schizotypy in first-degree relatives of individuals with schizophrenia and non-psychiatric controls

Abstract

Individuals with schizophrenia have very high rates of cigarette smoking, and much has been discovered about the influence of nicotine on brain functioning in schizophrenia. However, less is understood about the relationship between nicotine consumption and milder phenotypes related to schizophrenia, specifically schizotypy. This study examined the relationship between nicotine consumption and schizotypy in two unmedicated samples that included first-degree relatives and non-psychiatric controls.Forty-two first-degree relatives and 50 control participants were administered a self-report questionnaire on schizotypal features as well as a self-report questionnaire on smoking behavior. A positive relationship was found between smoking status and level of schizotypy, and higher levels of schizotypy significantly predicted the odds of being a smoker after controlling for gender and group status. Interestingly, group status was a significant moderator in the relationship between level of schizotypy and smoking status, such that the relationship between these two variables was only significant in the first-degree relatives. This is the first study to investigate the relationship between these variables in a sample of firstdegree relatives of individuals with schizophrenia. Those individuals with more schizotypal features are presumably at greater risk for schizophrenia-spectrum disorders and thus may be more likely to smoke cigarettes given the known biochemical effects of nicotine on overt positive and negative symptoms of schizophrenia. Although relatives did not differ from controls in their level of selfreported schizotypy, the significant relationship between smoking status and schizotypy in the former group is likely explained by their genetic vulnerability to schizophrenia-spectrum disorders.

Associations Between Past Alcohol, Cannabis, and Cocaine Use and Current Schizotypy Among First-Degree Relatives of Patients With Schizophrenia and Non-Psychiatric Controls

“…Third, frequency/amount of alcohol use in the 25 to 29-year age range was directly correlated with current SPQ cognitive-perceptual, interpersonal, and total scores, frequency/amount of cannabis use in the 20 to 24-year age range was directly correlated with the SPQ interpersonal score, and all four SPQ scores were significantly and strongly directly associated with frequency/amount of cannabis use in the 25 to 29-year age range. These results suggest that the use of addictive substances, particularly cannabis (but also nicotine, based on previous findings reported by Esterberg and associates [27]), is related to schizotypy in complex ways. Greater elucidation of these associations, ideally using longitudinal research designs, could provide crucial information not only on the connection between substance use and schizotypy, but between substance use and schizophrenia.…”

“…The interviewer continued with subsequent age periods following the same procedure. For example, if a 35-year-old participant reported that he/she began smoking cannabis at age 16 years, the interviewer asked the participant to give an average frequency (per month) and the amount in joint equivalents (per usage) for ages 16-19 years, and then asked about average frequency and amount for the next two age periods (20)(21)(22)(23)(24)(25)(26)(27)(28)(29). Amounts were designated by units, such that one unit of alcohol equaled one beer, glass of wine, liquor drink, or shot; one unit of cannabis equaled one joint; and one unit of crack cocaine equaled one rock.…”

“…Use of the three specific substances was operationalized in three ways: (1) history of having ever used the substance, (2) age at onset of use of the substance, and (3) past frequency/amount of use of the substance during three time periods (15)(16)(17)(18)(19) years, 20-24 years, and 25-29 years). Esterberg and colleagues [27] reported a positive association between cigarette smoking and level of schizotypy in the sample of relatives of patients with schizophrenia. This study aimed to extend these initial findings by assessing relationships between the use of other addictive substances and schizotypy.…”

Altered time-perception performance in individuals with high schizotypy levels

“…Moreover, the use of this group also allows differentiation between specific traits and symptoms associated with schizophrenia and their impacts on the ability in question 26,[31][32][33] .…”

Differential effects on T-cell function following exposure to serum from schizophrenia smokers

“…30 Furthermore, a positive relationship was found between smoking status and level of schizotypy, where higher levels of schizotypy significantly predicted the risk of being a smoker after controlling for gender and group status. 31 Heavy smoking in patients has been regarded as an attempt of self-medication and there is evidence that nicotinic agonists improve clinical ratings of negative symptoms that are generally resistant to treatment with dopamine antagonist anti-psychotic drugs. 32 This implies that cigarette compounds may activate compensatory or beneficial mechanisms ameliorating the pathophysiology of the disease.…”