Description of the sample
Participants were aged between 29 and 61 years, with an average age of 42 years; seventeen men and three women took part; and 17 participants were born in Australia. The three participants born outside of Australia reported their countries of origin as Vietnam, England and Italy. None of the sample participants identified as being Aboriginal or Torres Strait Islander. Two participants had a diagnosis of schizo-affective disorder, and eighteen had a diagnosis of schizophrenia. The main antipsychotic medications that participants reported being prescribed were clozapine, olanzapine and paliperidone.
Forty percent of interview participants reported experiencing current issues with alcohol and/or other drugs, with 12 identifying as regular smokers, smoking an average of 21 cigarettes per day (eight of these individuals reported smoking a pack of 25 or more per day). In relation to other substance use as identified by SSI scores on the ASSIST, 15 participants were identified as being in a ‘moderate’ or ‘high’ risk category for tobacco (11 and four respectively); six in a ‘moderate’ or ‘high’ risk category for alcohol (four and two respectively); two in a ‘moderate’ risk category for cannabis; and one in a ‘moderate’ risk category for opioids. This is consistent with previous studies that suggest that a significant proportion of people diagnosed with serious mental illness have comorbid substance use disorders [20].
Participants’ SSI scores for caffeine revealed that the majority fell into a ‘moderate’ risk category (eighteen people), while two participants were in a ‘high’ risk category. These scores were highly representative of the larger sample that completed caffeine use questionnaires. Other than issues relating to substance use, participants did not report any co-morbid mental health disorders.
Patterns of caffeine consumption
For the majority of participants, caffeine consumption began in the morning shortly after waking and continued throughout the day. More often than not, participants began their mornings by consuming either coffee or tea. Caffeine consumption in the morning was particularly meaningful for participants and was framed as a “rich ritual” that enabled individuals to ease into their day. Only one participant drank caffeine almost exclusively in the evenings. On average, participants consumed 2.4 different types of caffeinated drinks in any given week, including: Coca-Cola (fifteen people), instant coffee (twelve), tea (six), brewed coffee (four), iced coffee (three), and energy drinks (two). Eight participants reported consuming three or more different types of caffeinated drinks in any given week.
The place of caffeine in participants’ lives
Two distinct groups of caffeine consumers emerged from the interviews. The first group saw their caffeine consumption as a trivial issue and did not see the reason for the strong focus of questioning about caffeine. For example: “I don’t know why [I drink caffeine], I think just boredom and things like that”. The second group were much more aware of their caffeine use and were able to articulate their reasons for use. These participants described the important role of caffeine in their lives and had clearly reflected on their caffeine use in the past. For example, one participant referred to caffeine as “food for the soul”, whereas another considered it “one of the simple pleasures of life”. Many of the second group’s narratives described the ritualistic nature of their caffeine consumption. More often than not, it was framed as a habit that had developed over a considerable period of time, often beginning in childhood. Some participants could not imagine life without caffeine and discussed their caffeine use as essential for daily functioning. These participants framed their caffeine use more in terms of addiction or dependence.
Dependence and craving
While no direct measures of abuse/dependence were administered among interview participants, the average caffeine consumption of coffee drinkers within the sample was 523 mg per day (which is considered a ‘significant health risk’ [2, 3]), and half of participants reported feeling that they had minimal control over their caffeine consumption, with some indicating an inability to live without caffeine. For example:
“I was vampirical [sic] on coffee like just drinking it like it was my life source”.
“I don’t miss cigarettes either, but coffee, I have to have coffee…I don’t think I could live without coffee”.
“I’d be lost without my Coca Cola. I couldn’t survive without it…I can’t get off to sleep without it…I need to have a certain amount each day to get me through”.
Other participants were less emphatic in their responses, but still expressed feelings of needing or wanting caffeine:
“I just felt like I needed it…If I didn’t have a cup of coffee in the morning or something I felt a bit dizzy”.
“It’s addictive and I just enjoy it…I bought tea a few weeks ago and I tried to replace a tea for a coffee, I found it very hard…I’d like to not be as dependent on it, but it’s just a natural thing just to wake up, put the jug on, make a cup of coffee”
For the abovementioned participant, the need to consume caffeine overrode the sub- optimal conditions of her accommodation in which to prepare caffeinated drinks:
Participant: I’ve tried cutting down, but that’s a waste [of money]… and the thought to have it was just too strong. So I wake up at say nine, have breakfast then I go straight to my room and I have two or three coffees. Interviewer: Is there a reason why you drink two or three in a row as opposed to just one?
Participant: I think because I get water from the hot water tap, it’s not really hot water, it’s lukewarm.
Interviewer: OK is there any reason why you don’t use a kettle? Participant: We’re not allowed to have them…for safety reasons.
Benefits of caffeine use
The stimulating properties of caffeine were one of the primary motivations for morning consumption; many people enjoyed the “boost” and the “buzz” from caffeine. One participant mentioned that “like everyone I’m a bit lethargic waking up and all that sort of stuff, but then I put on the kettle as soon as I wake up”. This appeared to be an experience shared by the majority. Some participants used caffeine for relaxation. For example, one participant almost exclusively consumed coffee in the evenings as a way to “chill out” in the same way that another person might drink alcohol: “I wouldn’t call myself a coffee, caffeine addict, but yeah I don’t mind having a couple of…oh like probably in the night, I don’t know five cups or something”. Others consumed caffeine throughout the day and used caffeine as a reward or used their caffeine break as a way to disrupt their routine, for example:
“It gives me a bit of time out…A break from the pressures of the day”.
“When I’m working I have a coffee after about two or three hours, just to fill in, as a break”.
“Yeah it’s sort of like a luxury thing, yeah you just feel like it”.
Some participants were staunch advocates for caffeine and looked for ways to justify their use. For example, one participant said they had “heard on the news the other day that people who drink coffee live longer…I thought I’m coming to see you today, I’ll remember to mention the fact that coffee drinkers live longer”.
The majority of respondents reported consuming caffeine, at least in part, for its pleasurable taste. In particular, the sugary taste was identified by participants as an important factor in their enjoyment of caffeinated drinks. Some participants chose soft drinks, instant coffee and iced coffee over brewed coffee for this reason:
“You can’t kill it [brewed coffee] with sugar like the other stuff…I prefer instant, the instant stuff’s smaller, you know more smooth and creamy as opposed to the others”.
“[Iced coffee is] a bit sugarier and tastier [than instant coffee] and moorish is probably the right word for it”.
“I like the sweetness in the Coca Cola, the sugar and that”.
However, some participants also continued to consume caffeine even though they reported not enjoying the taste; for two individuals the perceived benefits of caffeine overrode their distaste for the drink. There was a strong link between drinking caffeine and smoking cigarettes, consistent with previous research [7, 21, 22]; irrespective of whether participants were current or former smokers, there was a general sense that caffeine and nicotine “go hand in hand…combined, they both taste good”. Previous literature suggests that caffeine ingestion increases reinforcement from nicotine [21–23], and that caffeine use may be a contributing factor in the onset, maintenance of or relapse to tobacco dependence [21], which may provide some explanation for the high rates of concurrent caffeine use and smoking among participants.
The final motivation for caffeine use cited by participants was the social aspect of consumption. It is well documented within the literature that people with a diagnosis of psychotic illness experience issues around interpersonal relationships and loneliness [24–26] so it is unsurprising that almost half of participants cited the social aspects of caffeine consumption as being a primary motivator for their behaviour:
“[Drinking caffeine during childhood] was about bonding with my mum…having a coffee and a biscuit and stuff”.
“Once or twice a week I go for a coffee with my friend… I usually ring up a friend and go for a coffee and have a chat”.
“It’s just such a nice social thing. The Italians do it and the Greeks do it…it’s like when you go to someone’s house, do you want a cuppa? My friend comes each night and we have a coffee, a biscuit, then dinner…People meet and greet over coffee, friends, old friends and family, you know”.
“In the hospital…with people with mental illness it’s a sort of a starting point, it’s a social thing, you know cigarette, bottle of coke and when you speak to other people with mental illness you know it revolves around cigarettes and Coca Cola”.
A number of participants couched their caffeine consumption in terms of caffeine’s perceived social acceptability compared to other substances such as alcohol or cannabis. It appeared as though social perceptions about caffeine played a significant role in participants’ decisions about consumption, particularly around being seen to be “trendy” or “fashionable” by others. The desire to be perceived in a certain way through the consumption of caffeine within a social context might relate to the challenge of social inclusion for people experiencing enduring mental illness.
Perceptions of caffeine compared to other drugs
Participant’s perceptions of their caffeine use were influenced by the social positioning of caffeine use as a substance they perceived as less harmful than other licit and illicit substances, namely alcohol, cannabis, cocaine, methamphetamine and heroin, but most still considered caffeine to be a stimulant, “like a drug”:
“Amphetamines are far stronger, but it [coffee] does do that, it makes you race a bit…The coffee sort of makes you feel like you’re on speed”.
“I do perceive it as a stimulant but I wouldn’t perceive it as something that could create that much harm unless it was taken in extreme amounts”.
“I don’t see it as a big deal… I know a lot of people who have no addiction or anything to it”.
“I don’t even think it comes even close [to illegal drugs]… it’s legal, it’s normal as far as I’m concerned. Yeah it might have you know the side effect of keeping you awake or more alert whatever they’re saying about coffee, but I would never even put it in the same category as drugs like that”.
“Well it’s definitely not the worst [substance]…things like alcohol and other drugs are a lot more damaging than caffeine”.
These perceptions of caffeine compared to other substances seemed to temper participants’ responses about their expectations of the risk of harm associated with consuming caffeine. With the exception of a few individuals who had experienced significant impacts on their physical or mental health, participants generally regarded caffeine as one of the ‘safer’, more socially acceptable substances that they could be consuming.
Negative effects of caffeine
Few participants expressed concerns about their caffeine consumption in terms of either short or long-term harms. However, when prompted, a number of participants reported experiencing negative side effects from what they considered excessive caffeine consumption, including experiencing dry mouth; insomnia; bloated stomach; blurred vision; anxiety; hallucinations; nausea, and vomiting. For most, the experience of these side effects was not significant enough to elicit a change in their consumption. In fact, many participants had not experienced negative side effects and did not believe that caffeine was harmful. Those who stated concerns about caffeine were most often in relation to the consumption of soft drink as opposed to coffee.
A small group (three people) perceived caffeine to be a potentially harmful drug and framed their caffeine consumption in terms of attempts to cut down or quit. Some participants explicitly discussed their recent efforts to cut down or cease their caffeine consumption; however, almost all of these individuals had returned to their previous levels of consumption. For example:
Participant: If I do things like go to the gym after I’ve had some tea like I did yesterday, it affected me after the gym. I start hearing voices and get a fair bit of anxiety and stuff like that… I don’t know whether I’m addicted to it or…I also like the taste of Pepsi Max so much I, I’d like to still be able to drink it, but I’ve cut down since [realising it was contributing to psychosis] I haven’t had any Cola for a little while… Interviewer: So when you say you don’t know if you’re addicted to it, what would… How do you think that that would look?
Participant: I guess you’d, you’d want to be drinking it every day…Which I’m doing pretty much, but I mean because of the psychosis yesterday I didn’t have any.
This participant had also ceased consumption of coffee as it was contributing to his experience of psychosis:
Interviewer: And what about coffee, you’ve never liked the taste of coffee?
Participant: No I love the taste, but I just went off it because it was affecting me [increasing frequency of psychosis] too much…It sort of got stamped in my brain I guess that if it was coffee then no matter how strong it was, whether it was normal coffee or a decaf, it just stamped in my brain that it was going to affect me.
One participant recounted that their high levels of caffeine consumption had affected their physical health to the point that they had recently been admitted to hospital, but had since been able to decrease their consumption. This participant did not specify what their physical health condition was, but stated that:
“I was drinking it [instant coffee] all day…right up to about eight o’clock at night and I couldn’t control myself. I just for some reason couldn’t control myself and that so eight o’clock at night would be my last coffee and then during the night I felt like I couldn’t sleep because of it…I was also drinking probably four or five 1.25 litre [bottles] a day…I ended up in hospital for five days, because the fizzy drinks blew, blew my tummy up a lot…I had a tube up my nose and back down my throat and yeah”.
The experiences outlined above represented the most significant impacts on participants and were indicative of the severity of risk of harm required to warrant a decrease or cessation of caffeine consumption.
Most participants stated a preference for caffeinated drinks with high sugar content or that tasted ‘sugary’; however concurrently expressed an awareness of the potentially harmful effects of sugar on their physical health. A handful of participants had changed their consumption practices as a result of this perceived risk:
“Sometimes I had one 1.25 Litre bottle of normal Coke and I thought oh this tastes great and hang on a sec I shouldn’t have drunk that because of the sugar and yeah I changed. Yeah that full on sugar rush is not very good for me”.
In general, though, participants were uninterested in changing their level of sugar consumption unless a trusted authority e.g. General Practitioner made a recommendation to that effect.
Caffeine and interactions with medication
Some participants consciously reflected on the interaction between caffeine use and their medication. For example, one participant suggested that drinking caffeine “will actually help break down medication…research says that four or five coffees a day actually help your liver function”. This participant reported that:
“When I was taking hard tabs [of antipsychotic medication], I’d have a couple of coffees to whack it down [sic] in my bloodstream…If I was taking a lot of hard tablets I would probably consume more Coca-Cola or coffee to break it down”.
This participant believed that caffeine consumption improved their liver function, and believed that the stronger the dose of medication they were taking, the more caffeine they would need to consume to metabolise it. Further, other participants emphasised the importance of caffeine consumption to counteract the sedation that they experienced after taking medication: “Clozapine makes me quite drowsy, so when I wake up in the morning…those first cups of coffee are really handy”. Others had noticed that caffeine consumption had an impact on the effectiveness of their medication, but found it difficult to verbalise the specific interaction with caffeine:
“It’s probably not the best habit to have, drinking too much [coffee] because I do think it does keep you awake far longer than you should…I don’t know for certain how it effects the medication, but I do think that there’s…it’s a definite yes as far as the effectiveness of it [medication]… Because like I said, when I have taken it, even when I’m exhausted I’ve already probably drank four or more coffees than I probably usually would and there’s still that agitation and not as easy to get to sleep. Whereas if I stick to what I usually do, within half an hour of taking the medication it’s pretty much guaranteed that I’m gonna [sic] be falling asleep”
“I’ve been on Seroquel and stuff like that and when I was drinking coffee and taking that medication, it triggered like…it had a very stimulating effect, I thought it was maybe to do with combining the medication and coffee”.
“You see with clozapine it puts me to sleep regardless of the caffeine I drink during the day…but I was also told, the doctor told me once that drinking Coca Cola can affect the levels of clozapine in your blood”.
Even though participants’ reflections did not all concord with previous research around interactions between caffeine and antipsychotic medication, it was noted that participants were aware of psychological and physiological changes associated with medication use and caffeine consumption, even though close to eighty per cent of the larger sample of 59 participants stated that no-one had told them about possible interactions. The suggestion by some participants that they noticed changes in the effects of their medication based on their caffeine consumption indicates that further research into these interactions is warranted, particularly in light of recent clinical studies, which provide evidence of a robust effect of caffeine on decreasing serum clozapine levels among some individuals [27, 28].