The National Advisory Committee on Drugs and Alcohol (NACDA) has recently published Bulletin 41 in a series of reports on the 2014/15 survey on drug use in the general population in Ireland.2 The bulletin focused on polydrug use in the adult population. Polydrug use was defined as the use of any two or more substances, legal, illegal or prescribed, within a one-month period.
Twenty-three per cent of survey participants had not used any substance (either legal or illegal) within the last month. The most commonly used substance was found to be alcohol, with 32.7% reporting alcohol consumption in the month prior to the survey. The most common combination of substances in the population was found to be alcohol and tobacco (10.5% reporting use of both in the last month), and the percentage of those reporting the use of alcohol and other legal drugs was found to be 8.1%.
The combination of alcohol, tobacco and any illegal drug was 2%, which is higher than the proportion reporting use of tobacco and other legal drugs (1.1%), or alcohol and antidepressants (0.8%). All other combinations of polydrug use reported were 0.5% or less.
A higher percentage of females (26%) than males (20.3%) had not used any substance (legal or illegal) during the last month. A greater proportion of males consumed alcohol (36.8%) compared to females (28.7%), which was also true for the combination of alcohol and tobacco used in the last month (13.2% males vs 7.9% females). Males were also more likely to report the use of illegal drugs combined with alcohol and tobacco (3.2% males vs 0.8% females). However, a higher percentage of females reported that they had used alcohol with other legal drugs compared to males (9.2% vs 6.9%).
The prevalence of alcohol and tobacco use in young adults aged 15-34 years was found to be 12.6%, which was higher than that reported by older adults aged 35-64 years (10.9%) and over 65s (4.3%). Polydrug use of alcohol and other legal drugs was found to be similar for younger and older adults (8.5% and 8.7%, respectively), and lower in participants who were over 65 years (5%).
In younger adults, illicit substances were most commonly used in combination with alcohol and tobacco (4.3%), while 0.9% of older adults reported this combination in the month before the survey. Older adults were more likely than younger adults to have used alcohol and antidepressants (1.4% vs 0.2%).
Relationship between use of particular substances and of other substances
Patterns of association between pairs of substances are presented in Table 1. For respondents who indicated using alcohol in the previous month, 30.2% had also used tobacco, while 5.9% had also used cannabis. A high percentage of people who used tobacco also reported the use of alcohol (71.5%), while 13.2% had also used cannabis and 7.7% also used antidepressants. Participants who indicated using cannabis in the month prior to the survey were also more likely to report alcohol use (87.4%) and/or tobacco use (82.9%), while 20.2% of people who used cannabis also reported the use of amphetamine-type stimulants (ATS).
A majority of people who used ATS had also used alcohol (97.1%), tobacco (90.9%) and cannabis (87.4%), while 25.1% had also used cocaine. Among respondents who had used cocaine in the previous month, 83.6% had also used tobacco, 76.6% used cannabis, and one-half of people who used cocaine (50.1%) had also consumed ATS.
Since the 2010/11 survey, there has been a significant increase in the proportion of people who drink alcohol, who use tobacco, and who use cannabis among people who use ATS (+1.4, +3.1 and +18.0 percentage points, respectively). The proportion of those who used alcohol, tobacco or cocaine in the last month, and who also reported using cannabis, has also increased significantly since 2010/11 (+2.6, +5.6 and +35.7 percentage points, respectively).
- Other main findings from the NACDA survey include the following:
- Among people who use alcohol, males are more likely than females to have smoked tobacco (33.5% vs 26.2%) in the last month, or to have used cannabis (8.3% vs 3.1%).
- The proportion of males who use cannabis and who also report the use of cocaine is almost double that of females (10.0% vs 5.4%).
- Since 2010/11, the proportion of people who use tobacco, and who also use alcohol, has decreased significantly for males and females (from 83.1% to 76.7% in males and from 72.5% to 64.9% in females), while the percentage of people who use tobacco, and who also use cannabis, has increased significantly (from 11.2% to 17.6% in males and 3.1% to 7.7% in females).
- The proportion of respondents who use sedatives or tranquillisers and who also use antidepressants has increased since the 2010/11 survey (+6.8 percentage points). Similarly, the proportion of those using antidepressants who also use sedatives or tranquillisers has increased by 4.6 percentage points.
1 National Advisory Committee on Drugs and Alcohol (NACDA) and Department of Health (UK) (2018) 2014/15 Drug prevalence survey: polydrug and new psychoactive substances results. Bulletin 4. Dublin: NACDA.
2 National Advisory Committee on Drugs and Alcohol (NACDA) and Department of Health (UK) (2016) Prevalence of drug use and gambling in Ireland and drug use in Northern Ireland. Bulletin 1. Dublin: NACDA. https://www.drugsandalcohol.ie/26364/