Caffeine levels in saliva: associations with psychosocial factors and behavioural effects

Abstract

The present study had two main aims. The first was to examine associations between psychosocial factors, health-related behaviours, regular level of caffeine consumption, time of day and levels of caffeine in saliva following acute caffeine challenges. The second aim was to determine whether individual differences in changes in performance following ingestion of caffeine were related to levels of caffeine in saliva. One hundred and forty-four young adults participated in the study. Questionnaires were administered prior to the study to measure psychosocial characteristics, health-related behaviours and habitual levels of caffeine consumption. Two double-blind acute caffeine challenges were then carried out 1 week apart. Volunteers were given either placebo or 1.5 or 3 mg/kg of caffeine on each occasion. The challenges were carried out at 8 : 00, 11 : 00, 14 : 00 or 18 : 00 h so that the impact of time of day could be assessed. In the week between the two challenges the volunteers consumed either caffeinated or decaffeinated products. This allowed investigation of the effects of caffeine withdrawal on caffeine metabolism. Prior to each caffeine challenge volunteers performed a range of tasks, and a baseline saliva sample was taken. The tasks were repeated 1 h after ingestion of the caffeine, with saliva samples being taken at the start and end of the 1 h test battery. The results showed that the level of caffeine in the saliva was a good indicator of the dose of caffeine consumed and of compliance with the withdrawal manipulation. Caffeine levels were not influenced by time of day, habitual caffeine consumption, psychosocial factors or health-related behaviours. Individual differences in caffeine levels in saliva were not related to the individual variation in the effects of caffeine on performance. Copyright 2001 John Wiley & Sons, Ltd.

Caffeine, Mental Health, and Psychiatric Disorders

“…However, Brice and Smith [25,26] found that the improved mood and enhanced performance after a single dose of 200 mg were also present with four doses of 65 mg given at hourly intervals.…”

Effects of caffeine on mood and performance: a study of realistic consumption

“…The mean age of the sample was 20.96 years (range 19-23 years); the mean weight was 71.91 kg (range 60-86 kg); and the mean daily caffeine consumption, assessed by self-report, 210 mg (range 100-375 mg). In order to directly compare the two methods of administering the caffeine conditions, it was essential to control for factors known to influence caffeine metabolism (Brice and Smith 2001b). Participants were not eligible for the study if they were female, taking medication or if they smoked.…”

“…It was predicted on the basis of our previous research, and the findings of other researchers, that caffeine would increase alertness (Smith et al 1993;Warburton 1995;Brice and Smith 2001a), increase anxiety (Loke 1988;, reduce simple reaction time (Clubley et al 1979;Smith et al 1994;Smith et al 1997) and improve sustained attention (Smith et al 1992;Brice and Smith 2001b), dual-task performance (Kerr et al 1991) and the encoding of new information (Smith AP et al 1999). The aim of the present study was to determine whether these effects would be observed with both administration of multiple small doses and a single large dose of caffeine.…”

Effects of Caffeine on Salivation

“…Among documented clinical effects of caffeine are increased heart rate, systolic blood pressure and left ventricular output [7,8,11] stimulation of autonomic responses [12,13] decreased tone of the gastrointestinal smooth muscles increased ocular pressure in glaucoma patients [14] central nervous system excitation and increased alertness [2,5,9] However, the only study we were able to find documenting the response of salivation to ingestion of any methylxanthine was a retrospective analysis of Pavlovian date [15]. Nevertheless, in the dental community, the belief that caffeine consumption decreases salivary production is widely held [6].…”

“…Like all exocrine secretions, salivary production is under the control of the autonomic nervous system, but physical factors such as hypovolemia and dehydration can also play a role. Thus, various systemic conditions, medications, and psychological factors can affect salivary output [1,2].…”