Shorter interpuff interval is associated with higher nicotine intake in smokers with schizophrenia

People with schizophrenia are frequent and heavy smokers.

The objective of this study was to measure serum nicotine levels and ad libitum smoking behavior for 24+2h using the CReSS micro topography device in 75 smokers with schizophrenia (SCZ) and compare these to 86 control smokers (CON) without mental illness. Mean values of repeatedly measured topography variables were compared using three-level nested linear models to adjust for between subject differences and the double nested data.

Smokers with SCZ smoked more cigarettes in the 24h period and took an average of 2.8 more puffs per cigarette than CON (p<0.001). The time between puffs, or interpuff interval (IPI), was shorter in SCZ by an average of 6.5s (p<0.001). The peak flow rate was higher in SCZ by an average of 4.9 ml/s (p<0.05). Smokers with SCZ spent an average of 1.0 min less time smoking a single cigarette vs. CON (p<0.001). Smokers with SCZ also had shorter IPI and more puffs per cigarette in an analysis of first cigarette of the day. For all subjects, a decrease in IPI by 1s was associated with an increase in serum nicotine of 0.19 ng/ml and in cotinine of 5.01 ng/ml (both p<0.05). After controlling for diagnosis group, higher craving scores on QSU Factor 2 (urgent desire to smoke) were associated with shorter IPI.

Smokers with schizophrenia demonstrate more intense cigarette puffing that is associated with greater nicotine intake. This pattern may provide insight into other heavily dependent smokers.