The mixed presentation of mood and anxiety symptoms in amphetamine users is reported in both surveys of forensic populations (Kalechstein, Newton, Longshore, van Gorp & Gawin, 2000) and cross-sectional community samples (Goodwin, Stayner, Chinman, Wu et al., 2002; Hall, Hando et al., 1996; Vincent et al., 1999). In an Australian study Hall et al. (1996) found that injecting amphetamine users reported a high occurrence of psychological problems, particularly depression and anxiety. At least three-quarters of the sample experienced symptoms of depression and anxiety. Although these high levels are partly due to the prevalence of anxiety and depression prior to amphetamine use (48–62%), around half of the sample (48–58%) reported experiencing symptoms after an episode of amphetamine use. Following first use of amphetamines, substantially more users reported experiencing symptoms of anxiety, panic, depression, mania, hallucinations and paranoia. Significant increases in violence also occurred after first use.
Hall et al. (1996) found that the best predictors of poor psychological morbidity were frequent use of amphetamines in the past six months, injecting amphetamines rather than snorting or swallowing them and the self-report of psychological symptoms prior to drug use. Similarly, Vincent and colleagues (1999) found that the factors that were significantly associated with mental health problems occurring since the first use of amphetamines were severity of amphetamine dependence; number of mental health problems predating first use of amphetamines; recent amphetamine use; and frequency of benzodiazepine use.
There is some indication that amphetamine use is associated with higher rates of mental health problems compared to other psychostimulant users (e.g., cocaine). In a community sample of drug users with relatively low levels of dependence, psychostimulant use was associated with a range of adverse events. Further, amphetamine use was associated with the greatest number and most severe adverse events such as sleep disturbances, paranoia, depression, anxiety and irritability compared to ecstasy and cocaine use (Williamson, Gossop, Powis, Griffiths et al., 1997). Rawson et al. (2000) compared medical and psychiatric symptoms at admission for methamphetamine users (n=55) and cocaine users (n=224) who presented to treatment from 1989–1995. Hallucinations were reported by over a third of methamphetamine users compared to a quarter of cocaine users; approximately 20% of methamphetamine users were rated as severely depressed compared to 12% of cocaine users and 7% of methamphetamine users reported suicidal ideation compared to 3% of cocaine users. Whilst there was no difference in retention in treatment between the two groups, a later paper (Rawson, Huber et al., 2002) reported that the methamphetamine users appeared to experience a longer period of depressive symptoms after cessation of use.
One factor that has been proposed as contributing to the apparent higher rate of psychological symptoms in current amphetamine users compared to cocaine users is the differential duration of action with the relatively short half-life of cocaine (40–60 minutes) compared to methamphetamine (approximately seven hours) contributing to the increased symptoms (Rawson, Huber et al., 2000). However, it is also possible that there may be differences in rates of a primary mood disorder that predate drug use. Using data from the Drug Abuse Treatment Outcome Studies (DATOS), Riehman et al. (2002) found partial support for this hypothesis with higher rates of depressive symptoms in amphetamine/methamphetamine users (35%) compared to cocaine users (26%) at intake. However, they found no evidence that these depressive symptoms persisted after cessation of drug use in either amphetamine/ methamphetamine users or cocaine users.
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Presentation and clinical course
Pharmacological treatment of mood and anxiety symptoms during withdrawal
Presentation and clinical coursePsychostimulant users may experience a range of anxiety and mood symptoms that are due to the direct effect of the drug during intoxication and withdrawal. High dose, regular use of psychostimulants produces dependence that is followed by a withdrawal syndrome on discontinuation of the drug. Whilst many of these symptoms are of short duration, four to five days, a number of studies suggest that some of the symptoms may continue for several weeks (e.g. Cantwell & McBride, 1998). It appears that these withdrawal symptoms fall into three groups, those related to hyperarousal such as craving, agitation and dreams, those related to reversed vegetative features such as loss of interest or pleasure and slowing of movement and, finally, those related to anxiety (Srisurapanont et al., 1999a). Dysphoric mood is also noted to be a major feature of the withdrawal syndrome.
Symptoms of withdrawal associated with amphetamine use are usually strongest within the first week after the initial 'crash' or 'come-down' from amphetamines and then wane over the following weeks. Most withdrawal symptoms abate between one and three months after cessation of amphetamine use. Clearly, further work is required to investigate the reliability of this grouping of symptoms and, more importantly, to determine the course of the withdrawal syndrome to ascertain which features are more enduring and should be medicated.
Whilst both mood symptoms and anxiety symptoms can occur during psychostimulant intoxication and psychostimulant withdrawal (see Chapter 7: Psychostimulant withdrawal and detoxification), there are occasions when the symptoms are considered to be in excess of those usually associated with either intoxication or withdrawal and warrant independent clinical attention (American Psychiatric Association, 1994). Under these circumstances, the DSM-IV (American Psychiatric Association, 1994) provides diagnostic categories that allow for the substitution of Psychostimulant Withdrawal with either Psychostimulant-Induced Mood Disorder or Psychostimulant-Induced Anxiety Disorder. A prominent and persistent disturbance in mood must dominate the clinical picture and there must be clear evidence that the symptoms developed during or within one month of substance intoxication or withdrawal for a diagnosis of Psychostimulant-Induced Mood Disorder. Similarly, there must be prominent anxiety, panic attacks, obsessions or compulsions dominating the clinical presentation with evidence that such symptoms developed during or within one month of substance intoxication or withdrawal for a diagnosis of Psychostimulant-Induced Anxiety Disorder.
Pharmacological treatment of mood and anxiety symptoms during withdrawalThere has been a substantial research effort directed at determining effective medications for cocaine dependence and withdrawal with a primary focus on the treatment of mood and anxiety that occurs on cessation of use. As the severity of cocaine withdrawal symptoms is predictive of retention in treatment and (short-term) abstinence (Kampman et al., 2001), an individualised symptom-focused approach may be necessary. Chapter 7: Psychostimulant withdrawal and detoxification and Chapter 8: Pharmacological interventions review the evidence for the effectiveness of pharmacological treatment during withdrawal.
There has been little focus on possible pre-existing mood disorders that may persist beyond withdrawal and require a long-term intervention. A complex issue for research in this area is to be able to differentiate between patients with a pre-existing disorder at the start of treatment and then, in turn, ascertain whether pharmacological management of a comorbid mood or anxiety disorder improves prognosis.