National Amphetamine-Type Stimulant Strategy Background Paper: Monograph Series No. 69
3.2 Negative cognitive and psychological effects
Table of contents
There is a range of short-term adverse consequences of ATS use. Some of the more serious mental health consequences of meth/amphetamine use are sleep disorders, psychosis, paranoid hallucination, agitation, confusion, severe panic, anxiety and depression (Dean, 2004). Many studies have documented reduced mood and feelings of anxiety in the few days following MDMA use (Curran, 2000). Other common side effects in the few days following ecstasy use include insomnia, drowsiness, depression and difficulty concentrating (Morgan, 2000). More limited research is available on the long-term adverse consequences, but it appears that long term users report lack of sleep, severe fatigue, reduced resistance to disease, psychological problems (panic attack, paranoia, hallucinations etc), mood swings and violence (Allen & Tresidder, 2003).
It is difficult to monitor the trends in harms associated with ecstasy use by using routine data sources, as many of these do not differentiate ecstasy from other ATS. While the relative lack of specific long-term research on the effects of ecstasy means it is less conclusive and more contentious, it is generally accepted that, particularly at high doses, some problems will result, including memory and cognition problems, and depression. As stated by Hammersley and colleagues (2002):
- There is considerable ignorance coupled to considerable apprehension about the long-term effects of Ecstasy. It is ironic that the very area that users are most concerned about is also the very area that medical, or other, science is least able to help with information” (p.156).
Cognitive deficits
Despite grounds to be concerned about the cognitive impact of long term ecstasy use, definitive evidence is lacking (Turner & Parrot, 2000). Studies of MDMA users, particularly heavy users, report poorer function on cognitive tests involving working memory and executive function. In a recent review of the literature, Parrott (2006) stated that objective deficits in working memory, attention, frontal-executive function and episodic memory tasks had been found in heavy ecstasy users. Other studies have found deficits in tests of logical reasoning and serial addition (McCann et al., 1999; Parrott et al., 1998). From a review of the literature, Morgan (2000) found evidence of selective impairment of episodic memory, working memory and attention. Such cognitive effects may be long-lasting. For example, Thomasius and colleagues (2006) found that verbal memory deficits in ex-ecstasy users did not improve even after 2.5 years of abstinence.Neurocognitive deficits have been found in samples of amphetamine users. Research in Western Australia, with a sample of dependent amphetamine users attending an outpatient clinic, assessed a range of cognitive abilities including information processing speed, attention, learning, memory and executive functions (Collins, Dyer & Fox, unpublished). The study found that, relative to published normative data, all the amphetamine users exhibited some form of deficit on the cognitive skills evaluated and performed significantly below expectations according to a measure of pre-morbid intelligence (Collins, Dyer & Fox, unpublished).
With regards to methamphetamine use, research shows that long-term exposure can result in pronounced neuropsychological deficits, with the most consistent and profound impairments observed in working memory, attention and executive function (Barr et al., 2006). Research to date has demonstrated specific deficits associated with prolonged methamphetamine use in tasks of auditory discrimination, auditory vigilance (London et al., 2005), working memory and word recall (Chang et al., 2005; Thompson et al., 2004). Attentional deficits have also been observed and may be related to decreased cognitive inhibition (Salo et al., 2002), and attending to irrelevant task information (Nordahl et al., 2003). Finally, as demonstrated by performance on the Stroop Interference Task, methamphetamine use can have adverse effects on domains of executive function, including abstract reasoning, planning and behavioural flexibility (Kalechstein et al., 2003).
It is important to note that research with ATS users is often confounded by polydrug use in these samples and the possibility of pre-existing psychological problems that make it difficult to draw strong conclusions. In particular, caution is recommended in interpreting data pertaining to long-term cognitive effects of ecstasy use, as use of this drug is most often seen in the context of polydrug use and the role of concomitant cannabis use in any cognitive impairment is yet to be adequately addressed (Croft et al., 2001).
Top of Page
Depression and anxiety
Symptoms associated with both depression and anxiety have been linked with ATS use. For example, from a review of the literature, Morgan (2000) concluded that there was growing evidence that chronic, heavy, recreational use of ecstasy is associated with sleep disorders, depressed mood, persistent elevation of anxiety, impulsiveness and hostility. Furthermore, the relationship between depressive/anxious symptomatology and ATS use may be stronger than the link with psychosis. For example, a recent study in Victoria found that up to 85% of amphetamine users may suffer from depression and/or anxiety compared to 7% who showed psychotic conditions (Nutting et al., unpublished).Both the 2004 National Drug Strategy Household Survey (NDSHS) and the 2006 Ecstasy and Related Drugs Reporting System (EDRS) included the Kessler Psychological Distress Scale (K10; Kessler et al., 2002) to measure the level and severity of symptoms of depression and anxiety among survey participants. It is important to counsel caution in comparing the findings because criteria for drug use and diagnostic cut-off scores differed between the surveys. In the NDSHS, those who had used the drug at least once in the previous month had the following K10 scores: for meth/amphetamine, 36% were low risk, 33% medium risk, 21% high risk and 10% very high for psychological distress; for ecstasy, 44% were low risk, 34% medium risk, 16% high risk and 6% very high risk for psychological distress (Australian Institute of Health and Welfare, 2005a); among the 2006 EDRS sample, who completed the K10, just over half (55%) scored in the medium risk range, followed by low risk (38%) and high risk (7%) (Dunn et al., 2007).
As already noted, investigating psychiatric problems associated with ecstasy is difficult due to high rates of polydrug use among those presenting with psychiatric symptoms and the possibility of pre-existing problems. To date, most research has investigated the proposed link between MDMA use and depression due to the common influence on serotonin levels in the brain. Sumnall and Cole (2005) conducted a meta-analysis of 25 studies investigating depressive symptomatology in ‘recreational ecstasy users’. A small association between ecstasy use and depressive symptomatology was found, but considered unlikely to be clinically relevant. The authors also highlighted their observation that drug histories were often poorly reported and polydrug use was mostly not controlled. A study by Roiser and Sahakain (2004) compared current and ex-ecstasy users with polydrug users who had never used MDMA and found no significant differences between the groups.
A recent study by Guillot and Greenway (2006) found no significant differences in depressive symptomatology on the Beck Depression Inventory-II (BDI-II; Beck et al., 1996) between heavy ecstasy users and ecstasy naïve college students. In addition, most ecstasy users who were diagnosed with a psychiatric disorder reported that the diagnosis preceded their use of the drug. A study by Soar, Turner and Parrott (2006) also considered premorbid psychiatric history in relation to the degree of self-reported problems attributed to ecstasy use. It was found that ‘problematic ecstasy users’ scored significantly higher than ‘nonproblematic ecstasy users’ on somatisation, depression, anxiety and negative psychobiology. ‘Problematic ecstasy users’ also reported significantly higher levels of use, and personal and family psychiatric histories.
From their review of the literature on psychiatric sequelae attributed to ecstasy use, Gowing and colleagues (2001) concluded that:
- Overall, these reports indicate a clear association between ecstasy use and subsequent short-term mood changes. More severe psychiatric sequelae, including depression, panic disorders, psychoses and anxiety, may occur but probably only in those individuals made vulnerable by personal or family history of psychiatric disturbance, by stress or by concurrent use of other drugs (p.34).
Thus, the exact nature of the relationship is complex and more research is needed to determine the causal pathways between mental health problems and ATS use. Specifically, mental health problems may pre-date and exist independently of ATS use, ATS use may contribute to the onset of mental health problems, or there may be a common and shared cause (Baker & Dawe, 2005).
Psychological problems have also been identified in samples of injecting drug users (IDU). Among the sample for the 2006 Illicit Drug Reporting System (IDRS), the majority reported methamphetamine as the drug most often injected in the last month (33%) and the last drug injected (30%) (O’Brien et al., 2007). While mental health problems were not analysed according to the primary drug used, 38% of the total sample reported experiencing a mental health problem other than drug dependence in the last six months. The most commonly reported problem was depression (27%) followed by anxiety (14%).
Psychosis
One of the possible consequences of ATS use, in particular methamphetamine, is the causal role in inducing a psychotic state. This association has been widely publicised in both the media and in academic research. Research has comprised of human experiments (in the 1970’s that involved giving participants doses of methamphetamine in order to induce psychotic symptoms), animal experiments, case reports, surveys of drug users, and imaging studies (to detect neurological structural changes). Despite efforts to explicate the nature of the association between methamphetamine use and psychosis, in general it has been concluded that it remains unknown how acute or enduring the status of psychosis is (Kingswell, 2007).Heavy users of ATS typically use less regularly than opiate users and ‘binge’ over a period of a few days and nights, often followed by the use of drugs such as benzodiazepines or other sedatives to ‘come down’ (Darke et al., 2000). Such bingeing can induce a temporary psychosis identical in symptoms to an episode of paranoid schizophrenia, and this psychosis can be reliably induced in people with no history of, or predisposition towards, mental illness (Darke et al., 2000). ATS use can also severely exacerbate psychotic symptoms in those already experiencing a psychotic state of some form (World Health Organisation, 1997).
A presentation at a recent Australian conference reported that those at greatest risk of methamphetamine-induced psychosis had a predisposition to mental illness, consumed the drug at higher doses, preferred injecting or smoking the drug and had an earlier age of initiation (Heffernan, 2006). Research conducted by Chen and colleagues (2003) compared pre-morbid characteristics and psychiatric co-morbidity among 445 methamphetamine users with and without a lifetime diagnosis of methamphetamine psychosis. Results were that those with the diagnosis were younger at first methamphetamine use, used larger amounts of methamphetamine, had significantly higher scores on the Premorbid Schizoid and Schizotypal Traits questionnaire (Foerster et al., 1991), and higher rates of major depressive disorder, alcohol dependence and antisocial personality disorder.
Research into the association between amphetamine use and psychosis has been conducted both in Australia and internationally. A cross-cultural study conducted by Srisurapanot and colleagues (2003) sampled methamphetamine-induced psychotic inpatients in Australia, Japan, Philippines and Thailand. This research found that persecutory delusion was the most common lifetime psychotic symptom, followed by auditory hallucinations, strange or unusual beliefs and thought reading. Auditory hallucinations were the most common current symptom, followed by strange or unusual beliefs, and visual hallucinations.
Top of Page
Another international study, sponsored by the World Health Organisation (WHO), involved data collection at four centres in the Asia-Pacific region – Australia, Japan, Philippines and Thailand (Ali et al., 2006). Very few similarities were found across the sites regarding extent, patterns and routes of methamphetamine administration. Australian participants were reported as the most experienced drug users in terms of lifetime number of drugs used and the age of onset for methamphetamine use. Australian and Japanese methamphetamine users predominantly injected the drug, while those from the Philippines and Thailand almost exclusively smoked the drug. While Australian participants had the highest prevalence of morbid depression, symptoms of psychosis were comparable between countries, with delusions being the most commonly experienced symptom. While very few participants in other countries reported past psychological treatment (aside from methamphetamine-induced psychosis), over 60% of the Australian sample had received some form of treatment.
A recent study conducted in Sydney concluded that the prevalence of psychosis among a sample of current methamphetamine users was 11 times higher than among the general population of Australia (McKetin et al., 2006a). Among the 309 methamphetamine users interviewed, 13% screened positive for psychosis, and 23% had experienced a clinically significant symptom of suspiciousness, unusual thought content or hallucinations in the past year. Those defined as dependent methamphetamine users were three times more likely to have experienced psychotic symptoms than their non-dependent counterparts, even after adjusting for history of schizophrenia and other psychotic disorders.
One of the primary issues raised during consultations concerned the psychotic symptoms induced by methamphetamine use, including associated acts of aggressive and violent behaviour. In addition to the contributing factor of increased purity of more recent formulations of meth/amphetamine, it was suggested that some consumers may be predisposed to violence and psychosis. This was in reference to the observation that while some regular users do not exhibit these behaviours, an occasional user may experience a psychotic episode.
Top of Page
