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Drug and Alcohol Dependence 93 (2008) 191–196
Commentary
Researching the intoxicated: Informed consent
implications for alcohol and drug research
Judith Aldridge a,∗, Vikki Charles b
aSchool of Law, University of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom
bNational Addiction Centre, Institute of Psychiatry, Kings College London,
4 Windsor Walk, Denmark Hill, London SE5 8AF, United Kingdom
Received 3 April 2007; received in revised form 4 September 2007; accepted 5 September 2007
Available online 22 October 2007
Abstract
This article considers the informed consent process in relation to carrying out research with intoxicated participants in ‘field’ research settings.
There is little discussion in the literature of the potential problems that the intoxication of research participants may pose to research. Intoxication is
a potential problem for all researchers but is heightened in field research that takes place in settings where participants are likely to be intoxicated,
such as licensed venues, in drug consumption rooms, or police custody suites. The risks to research participants that intoxication poses should
not be resolved by electing not to do research with intoxicated participants; it is argued that these risks can be managed to some extent, and are
offset by the benefits of such research. Moreover, intoxication (and the impairment of cognitive functions relevant to valid informed consent)
may not always be identifiable through behavioural or biochemical methods of detection. The search for accurate and field-practical methods for
identifying intoxication amongst participants is useful, but not the only strategy for researchers who want to ensure the validity of the consent
process. Suggestions are provided for devising research protocols that acknowledge and accept intoxication of research participants and attempt
to protect them. One solution is to side-step identification of intoxication per se as a strategic objective in the consent process, and turn instead to
established methods for ensuring that information has been understood by potential research participants.
© 2007 Elsevier Ireland Ltd. All rights reserved.
Keywords: Intoxication; Ethics; Informed consent; Research process; Alcohol; Illegal drugs
1. Introduction
Intoxication by alcohol and other psychoactive illegal/illicit
drugs1may compromise the informed consent process in
research. Intoxication can impair cognition and judgement that
are essential in order that potential research participants can
understand what participation in research involves, and thus
make informed decisions about their participation.
Researchers may be more likely to encounter intoxi-
cated research participants when the populations from which
researchers draw their samples are drug and alcohol users
themselves, and in settings where participants are likely to
∗Corresponding author.
E-mail addresses: Judith.Aldridge@manchester.ac.uk (J. Aldridge),
Vikki.Charles@iop.kcl.ac.uk (V. Charles).
1Under consideration here are the psychoactive substances primarily associ-
ated with intoxication in field-based studies: alcohol, and primarily illegal/illicit
drugs such as cannabis, ecstasy, and heroin.
be intoxicated at the time of obtaining consent: in the homes
of research participants, in ‘the streets’, in drug consumption
rooms, in licensed and other social venues. For example, the
last 15 years have seen a resurgence of venue-based drug and
alcohol research with the study of raves and club drug use, from
the first ‘dance drug’ research carried out and published in the
early 1990s in Britain (Newcombe, 1992) followed by studies
in Britain (Deehan and Saville, 2003; Measham et al., 2001;
Release, 1997; Riley et al., 2001; Sanders, 2005; Silverstone,
2006), the US (Kelly, 2006; Perrone, 2006; Yacoubian et al.,
2003), Australia (Gourley, 2004), and elsewhere in Europe
(Tossmann et al., 2001; van de Wijngaart et al., 1999) employing
this venue-based design. Quantitative in situ research has also
involved data collection with intoxicated participants, in which
consent will, of necessity, have been obtained from intoxicated
participants. Recently for example, Voas et al. (2006) carried out
surveys along with alcohol breath tests and oral fluid drug assays
using their ‘portal’ method outside electronic music dance events
to estimate levels of drug and alcohol consumption.
0376-8716/$ – see front matter © 2007 Elsevier Ireland Ltd. All rights reserved.
doi:10.1016/j.drugalcdep.2007.09.001
192 J. Aldridge, V. Charles / Drug and Alcohol Dependence 93 (2008) 191–196
We discuss here research participant intoxication regarding
the informed consent process where research occurs ‘in the
field’, as opposed to in other more controlled settings.
2. How researchers have dealt with intoxicated research
participants
The alcohol and illegal drug research literature provides scant
discussion or guidance in relation to carrying out research with
intoxicated participants. This suggests that many researchers
who encounter intoxication amongst their research participants –
particularly in field research where intoxication may be prevalent
– implicitly accept that research participants may be intoxicated
without questioning and unpacking issues around that intoxica-
tion. Researchers who have acknowledged the intoxication of
their research participants have dealt with it in one of two ways:
(1) excluding intoxicated participants; or (2) excluding those
deemed ‘too intoxicated’ to participate.
The first method is the more conservative: excluding the
intoxicated from (at least) the consent process, and often from
the research as well. A US survey found that even amongst
researchers conducting primarily (non-field-based) clinical out-
come studies, few had a policy for dealing with intoxicated
participants, and of those who did, ‘most indicated they would
attempt to keep the participant at the site until sober or until
transportation was arranged’ (McCrady and Bux, 1999 p. 190).
Others, in discussing research that involves administering the
‘substance of dependence’ to a drug user (College of Problems
of Drug Dependence, 1995; Foddy and Savulescu, 2006), argue
that heroin users are sufficiently free to consent to receive their
drug of addiction, but that consent must occur when the addict is
sober. The underlying assumption here is that the consent pro-
cess – or even the research itself – may be compromised by the
intoxication of research participants.
The second method for dealing with intoxication involves
‘screening out’ the more extremely intoxicated from being
selected for research, and is less conservative because only intox-
ication beyond a particular level is deemed problematic. Deehan
and Saville assessed visible signs of intoxication in their research
with club-goers in six venues in England on a scale from 0 ‘no
intoxication’ to 5 ‘extremely intoxicated’. Only those 90% of
potential interviewees considered ‘able to take part in the inter-
view comfortably’ were approached (scoring from 0 to 2 on
the scale) (2003). Those researching drug use by detainees in
Australia (Mouzos et al., 2006), and Britain via NEW-ADAM
(Bennett, 2000) have also excluded from their research those
deemed ‘too intoxicated’ to interview. The British NEW-ADAM
detainee study assessed ‘fitness for interview’ in part on the
basis of drug and/or alcohol intoxication, and those deemed unfit
included 29% for alcohol and 2% for other drugs, on the basis of
an initial impressionistic subjective assessment by the custody
sergeant. However, as Bennett points out, this did not guarantee
that interviewees were not intoxicated at the time of interview, as
it was observed that some of them found it hard to keep awake (a
feature of substantial use of depressant drugs such as alcohol or
heroin) (Bennett, personal communication). This method may
have been useful for ‘skimming off’ the extremely intoxicated,
but clearly was not able to identify all research participants who
were intoxicated in ways that interfered with data collection.
Both approaches address and problematise research par-
ticipant intoxication. Albeit in different ways, each approach
involves assessing intoxication in order to identify and exclude
intoxicated potential participants. We turn now to problems in
assessing intoxication.
3. Assessing intoxication
Intoxication involves being under the influence of the effects
of one or more psychoactive substances that may alter emotional
state, perception, judgement and performance. However, intox-
ication is not a straightforwardly identifiable state that occurs
in an easily measurable way when a psychoactive substance is
ingested, regardless of place, expectation, and individual dif-
ferences. Although biochemical markers for the presence of a
substance have sometimes been demonstrated to correlate with
the subjective effects of intoxication (e.g., Cone and Huestis,
1993), biochemical markers cannot accurately gauge intoxica-
tion itself. In relation to alcohol, for example, blood alcohol
concentration (BAC) is not a reliable indicator of intoxication
since the same BAC may have different effects in different peo-
ple, and different effects in the same person across different
circumstances including physical condition, personality, mood
and situation (Krober, 1998). Regarding the substances that field
researchers typically encounter – alcohol and illicit drugs –
biochemical detection is not suited to identifying intoxication
because it is geared to identifying the presence of substances
or their metabolites in the body. As such, biochemical detec-
tion does not take into account tolerance, rate of substance
metabolism, and other individual and context differences.
Some have turned to behavioural approaches to identifying
impairment thought to result from intoxication (e.g., Burns and
Moskowitz, 1977) because of (1) the inability of biochemical
detection to serve as a measure of intoxication; and (2) the
need for field tests that do not involve expensive, bulky equip-
ment or specialised technical expertise. However, success with
the use of behavioural approaches to detecting impairment due
to intoxication with illicit drugs is mixed, having been used
successfully with some substances but not others. For exam-
ple, Papafotiou et al. (2005) found that impaired performance
on field tests assessing driving impairment was positively cor-
related with THC dose; however, field test results were not
correlated with low levels of amphetamine intoxication (Silber
et al., 2005). Recent evidence by Perham et al. (2007) suggests
that subjective ratings of the physical manifestations of drunken-
ness (staggering gait, slurred speech, glazed eyes) of city centre
drinkers by trained observers corresponded with blood alcohol
concentrations. However, Brick and Carpenter (2001) found that
police officers, watching a video-recorded interview, were able
to correctly identify that alcohol-intoxicated subjects had been
drinking only at relatively high levels of blood alcohol concen-
tration (BAC 0.15–0.16%). Thus, intoxication may be difficult
to gauge even for police officers who are likely to be both trained
in doing so, and who encounter alcohol intoxication frequently.
Overall, these results suggest that observed behaviour is often
J. Aldridge, V. Charles / Drug and Alcohol Dependence 93 (2008) 191–196 193
not a very accurate predictor of substance level, suggesting that
it might not always be a useful tool for researchers concerned
about ability to give informed consent. Moreover, it is likely
that intoxication levels that affect cognitive functions, thus in
turn affecting the consent process, may not always be associ-
ated with observable impairment. Again therefore, behavioural
approaches to identifying impairment will have only limited util-
ity for researchers concerned about the ability of participants to
give informed consent.
4. The impact of intoxication on informed consent
Because of the effect of intoxication by some psychoac-
tive substances on cognition and judgement, it is likely that
intoxication could impact a participant’s capacity to understand
explanations about research and on the capacity to make deci-
sions about participation, by for example, impairing judgements
about the merits or drawbacks of participation. It is likely that
the impact of intoxication by some psychoactive drugs on feel-
ings or emotional state (Parker et al., 1998) (e.g., happy, sad,
scared, vulnerable and empathetic) may also colour perceptions
and judgements in such a way as to influence decision making.
There is research to suggest that alcohol intoxication affects sug-
gestibility (Santtila et al., 1999), risk-taking (Lane et al., 2004)
and moral reasoning (Fincham and Barling, 1979), all variables
that could play a role in informed consent. Intoxication may
therefore increase the chances of uninformed consent, reluctant
consent, or consent that is later regretted.
There has been no systematic research on the impact of intox-
ication on the informed consent process. However, there is some
evidence that intoxication may increase willingness to consent
to research, and thus influence decision making. In venue-based
research on dance drug use by Measham and colleagues, field-
work staff regularly reported their perceptions that intoxication
affected willingness to consent to interview. Indeed, respondents
agreeing to an interview reported having already consumed more
alcohol (8.3 units) than those who refused (6.6 units), a statisti-
cally significant difference, suggesting that alcohol intoxication
may increase willingness to participate (Measham et al., 2001,
p. 89).
5. Ethical principles to guide research with intoxicated
participants
Ethical decision making in most medical, health-related and
social research draws on principles which are relevant to con-
ducting research with intoxicated participants: (1) autonomy:
participants should be free to participate; (2) non-malificience:
participants should be protected from harm; (3) beneficience: the
benefits of research should outweigh the risks; (4) justice: people
should be treated equally (Beauchamp and Childress, 2001).
Intoxication could be seen to compromise the autonomy
of would-be research participants to consent, thus potentially
leading to harm. On the other hand, the benefits of increased
understanding generated about alcohol and other drug users in
natural settings where intoxication is prevalent could be seen
to outweigh the risks. This kind of research has a long and
distinguished history, much of it influenced by the ‘Chicago
School’ style of urban ethnography: Dai’s Opium Addiction in
Chicago (1937, 1970);Lindesmith’s Opiate Addiction (1947,
1968); and Preble and Casey’s Taking Care of Business (1969).
Although research with some groups (e.g., the very young or
old, those with physical or mental disabilities) can present spe-
cial challenges in order for researchers to achieve their inclusion
in research, it has been argued that to exclude them from research
conflicts with the principle of justice through discrimination
(Schuklenk, 2000) or through an unwillingness of researchers
to speak directly to respondent groups that present challenges
(Rodgers, 1999). Similar thinking can be applied to research
with the intoxicated.
Some researchers have addressed consent issues for carry-
ing out research with such ‘vulnerable’ groups where cognition
and judgement may be impaired or deficient in such a way that
normal procedures for obtaining informed consent are inap-
propriate or insufficient. The analogy with intoxication is not
perfect. An intoxicated person, qua their intoxication, is not
inevitably ‘vulnerable’; however, it is their status as potentially
vulnerable that concerns us here. Moreover, insights into the
informed consent process particularly from those researching
people with mental disabilities will be limited to some extent,
since the incapacities addressed for that population group will
be relatively enduring, whereas the relevant incapacities for
intoxicated people will be relatively transitory. Recommenda-
tions that flow from these and other insights are considered
below.
6. Recommendations
Although some researchers have taken a conservative stance
on the problem of intoxication to the informed consent pro-
cess by determining to exclude intoxicated participants from
aspects of the research process (i.e., considering the risks to the
participant too great), we contend here that the problem that
intoxication poses should not be resolved by electing not to do
research with intoxicated participants: (1) it is not possible com-
pletely to avoid the intoxicated, given the prevalence of the use
of and intoxication by alcohol and illicit drugs; (2) intoxication
is just one of a number of ‘altered states’ in which individu-
als find themselves, that include other common states such as
stress and heightened emotions. Attempting to secure the par-
ticipation of research participants who are in a ‘pure’ state (free
from intoxication or other factors that may interfere with their
cognitive processes in a way that impacts on providing con-
sent) is likely to prove impossible; (3) both biochemical and
behavioural methods for identifying intoxication (with a view
to excluding the intoxicated) are problematic. We should rather
seek to devise research protocols that acknowledge intoxication
and protect research participants, thus off-setting risk in the form
of potential harm to participants.
6.1. Ensuring understanding
One suggestion to enable people of varying capacities to
consent to participate in research is to ensure that information
194 J. Aldridge, V. Charles / Drug and Alcohol Dependence 93 (2008) 191–196
provided to them is comprehensible and appropriate, and then
check that the information has actually been understood. Sudore
et al. (2006) have demonstrated a method of ‘teaching then test-
ing’ potential respondents on information about their study, with
a view to excluding from the consent process those who, after
repeated teaching/testing, are unable to demonstrate adequate
understanding. Regarding intoxicated participants for whom
cognitive functioning may be diminished or altered, researchers
need to have appropriate expectations regarding a participant’s
ability to take in, process and act on the information they have
been given. Researchers may therefore consider building extra
time into research protocols to check that understanding has
occurred. For field research (which often takes place in busy
or chaotic environments), a verbal variant of this approach
could be used. The advantage of this approach is that it side-
steps the problem of assessing intoxication per se, and instead
jumps directly to attempting to ensure that information about
the research has been understood in spite of intoxication. As has
been argued, in relation to carrying out research with people with
mental disabilities (Fisher, 2003), that enhancing aspects of the
consent setting that reduce consent vulnerability (i.e., provid-
ing comprehensible information and ensuring comprehension)
may be preferable to conceiving consent competence as a ‘state’
within an individual; this may be a particularly important insight
as regards intoxication, which is mostly a relatively transitory
and changeable state.
6.2. Extending the timeframe for consent and consent
withdrawal
Lawton (2001), commenting on her ethnographic research
in a hospice, found that changes in the condition of patients
meant that they were not always able to state whether they
still wanted to take part in her research. The similarity between
intoxicated participants and Lawton’s dying patients lies in the
fact of their conditions being changeable in ways that may
be important regarding ongoing consent to participate. It is
likely that levels of intoxication will vary over fairly short
spaces of time (certainly hours, but even over shorter periods
than that). Given the connection between intoxication and emo-
tions/feelings and various cognitive processes, the willingness
of participants to continue may, during the course of partic-
ipation, change. If consent to participate in research should
be treated as a process rather than as a one-off event, as has
been argued (e.g., Ramcharan and Cutcliffe, 2001), it is sensible
for fieldworkers to be alert – and remain alert – to changing
signs of unwillingness to participate and to remind research
participants where appropriate that they may terminate their
participation at any time. Rodgers (1999) argues that there are
signs that participants use aside from verbal dissent to signify a
wish to opt out of participation that has already begun. A par-
ticipant who becomes distracted/disinterested/agitated/irritated
during an interview could be reluctant to continue. Being alert
to these signs, checking that participants are happy to continue,
and re-emphasising their right to withdraw at any time, should
be built into research protocols and fieldworker/interviewer
training.
Research participants may have regrets about their participa-
tion in the minutes, days or weeks following their participation.
A standard de-brief should allow participants the space to recon-
sider their participation before fieldworker and participant have
broken contact. The fieldworker can provide contact details that
participants can easily keep or take away with them in a small
and portable ‘credit card’ size. This allows the possibility for
a former participant to initiate contact so that consent can be
retroactively withdrawn, and effectively extends the time frame
over which the process of providing consent can occur into peri-
ods in which former subjects are sober. The idea of retroactive
withdrawal of consent is controversial, not least because it raises
the rarely articulated issue of ownership of data; in other words,
what are the limits of the ‘rights’ of a former research partic-
ipant to control the data that resulted from their participation
(see Wiles et al., 2006)? There are complexities in relation to
retroactive withdrawal of consent that researchers will need
to anticipate in their research protocols: what time limit for
withdrawal is suitable, and how data already collected will be
handled.
When researchers know that candidates for participation in
research are under the influence of alcohol or illegal drugs, they
may ask those who have already indicated a willingness to partic-
ipate whether they believe that the effects of their consumption
may have influenced their willingness. This question could pro-
vide potential respondents with the specific opportunity to reflect
on their intoxication in relation to their willingness to participate
in the research.
6.3. Training fieldwork staff for intoxication awareness
Research should be carried out by staff trained to be sensitive
to signs of intoxication outside of the more expected and com-
mon alcohol intoxication (loss of co-ordination, staggering gait,
drowsiness, slurred speech and glazed eyes). Signs of intoxi-
cation associated with other illicit drugs may also be assessed
(paranoia, anxiety, eye-rolling, pupil dilation/constriction, head
movements or jerks). It may be neither feasible nor desirable
that research staff should be clinically trained, but they should
have knowledge about the typical effects of the substances they
are likely to encounter during fieldwork, and be trained to be
aware of these, remembering to remind participants of their right
to withdraw, particularly when observable signs of intoxication
appear to change.
6.4. Excluding the obviously intoxicated at the outset
In spite of the limitations of visual/behavioural approaches
to identifying intoxication, the use of an initial visual assess-
ment of intoxication in order to screen out the most obviously
and extremely intoxicated research participants may neverthe-
less be good practice for researchers (e.g, Bennett, 2000; Deehan
and Saville, 2003). Although some very intoxicated participants
may ‘slip through the net’ (Bennett, personal communication),
excluding at least the most obviously intoxicated is a feasible
and achievable objective.
J. Aldridge, V. Charles / Drug and Alcohol Dependence 93 (2008) 191–196 195
7. Further research
Although this contribution addressed the implications for the
informed consent process of research participant intoxication
where research occurs ‘in the field’, as opposed to in other more
controlled settings, the implications apply also to some extent
to research carried out in more controlled (for example clinical)
settings, and also where research is conducted in the general pop-
ulation, such as in household surveys. The prevalence of drug
and alcohol use is well documented; the prevalence of intoxi-
cation in the general population with the range of psychoactive
substances remains undocumented. For example, it may be use-
ful to for household survey researchers to know how often people
are likely to be intoxicated in their homes during data collection.
Indeed, intoxication as a phenomenon remains under-
analysed within social research approaches to drugs and alcohol
research. In order to address this, social researchers need to
develop methods of conceptualising, operationalising and mea-
suring, and explaining and theorising intoxication for a range
of substances. Of particular importance should be assessing the
effect of intoxication on validity and accuracy of self-reports.
More systematic research is required to establish the effects of
intoxication by different drugs, or combinations of drugs, on the
consent process across diverse research contexts.
Conflict of interest
None.
Acknowledgements
Many thanks to Trevor Bennett, Karen Clarke, Phil Edwards,
Angela Melville, Toby Seddon and anonymous reviewers for
their comments and suggestions.
Work in the preparation of the manuscript was supported by
internal funds from the institutions of each author.
Contributors: Vikki Charles conducted some of the informed
consent literature search and summarised this literature. Judith
Aldridge drafted the manuscript. Both authors have contributed
to and approved the final manuscript.
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