Australians who used meth/amphetamine^† in the past 12 months were more likely to have been diagnosed with or treated for a mental illness (42%) than those who had not used meth/amphetamine in the past 12 months (16%).

In 2017-18 there were 14,726 hospital separations due to the use of stimulants^†.

In 2017-18, Australian men accounted for more hospital separations due to the use of stimulants^† than women.

In 2017-18, the largest proportion of hospital separations due to the use of stimulants^† occurred among 30-39 year olds (35%) followed by 20-29 year olds (33%).

In 2017-18, Australians were more likely to be hospitalised for mental and behavioural disorders due to the use of stimulants^† (91%, n=13,408) than for poisonings by psychostimulants^† (9%, n=1,318).

Methamphetamine use stimulates the brain and central nervous system, and can result in a variety of adverse outcomes. The effect that methamphetamine has on an individual depends on a number of factors. These include:

• how much methamphetamine is taken
• the method of use
• the form and purity of the methamphetamine
• the height and weight of the user
• the user’s current physical and mental health status
• the user’s previous experience with methamphetamine (i.e. new user vs frequent user)
• whether other substances (alcohol, tobacco, medications, or other illicit drugs) are used at the same time as methamphetamine.

There are a variety of mental health risks associated with methamphetamine use. Many of these risks are very serious, and can result in severe short- and long-term consequences for the user.

The effects of methamphetamine are the same regardless of which form (e.g. powder/base/crystal) is used. However, crystal methamphetamine (ice) tends to be more potent and purer than other forms. As a result, the effects of ice are both more likely to occur and likely to be more intense than when other forms of methamphetamine are used.

Short-term effects

The short-term psychological effects of using methamphetamine include:

• euphoria
• increased alertness and energy
• increased physical activity
• talkativeness
• heightened sexual arousal
• increased aggression or hostility
• feeling excited, agitated, anxious or panicky
• feeling very powerful or better than others
• symptoms of psychosis (a serious psychological problem which can involve hearing voices, hallucinations, paranoid delusions, and aggressive behaviour).

Methamphetamine use may also make existing mental health conditions (e.g. depression, anxiety) worse.

Long-term effects

The psychological effects of long-term methamphetamine use include increased risk of:

• anxiety, depression, and paranoia
• insomnia
• reduced concentration and poor memory
• psychosis or psychotic behaviour
• homicidal or suicidal thoughts
• violence.

Regular use of methamphetamine may also lead to dependence (addiction). Dependent users develop a tolerance to methamphetamine, and need to take larger doses of the drug to achieve the same effect and feel ‘normal’. The urge to use methamphetamine can become more important than other activities in their lives, resulting in poor physical and mental health, social and financial problems, and family and social breakdown.

For more information about the effects of methamphetamine, see FAQs What are the effects of methamphetamine use? and What are the physical health risks of methamphetamine use?

In 2016, a larger proportion of Australians who used meth/amphetamine^† in the past 12 months reported high or very high levels of psychological distress compared to those who did not use meth/amphetamine in the past 12 months.

The reference guide used by clinicians to diagnose mental health disorders is known as the Diagnostic and Statistical Manual of Mental Disorders (DSM). The most recent version of the manual, the Diagnostic and Statistical Manual of Mental Disorders – 5th Edition (DSM-5), was released in May 2013. Prior to this, the Diagnostic and Statistical Manual of Mental Disorders – 4th Edition, Text Revision (DSM-IV-TR) was used by clinicians and researchers from 2000 to 2013.

The diagnostic criteria for mental health disorders due to methamphetamine use differ significantly between the DSM-IV-TR and the new DSM-5. For the purposes of the NADK, all reported data on methamphetamine-related mental health disorders utilise the DSM-IV-TR diagnostic criteria. This is because the relevant mental health data reported in the NADK was collected prior to the publication of the newer version of the DSM (DSM-5).

DSM-IV-TR Diagnostic Criteria

According to the DSM-IV-TR, there are two main methamphetamine-related mental health disorders: substance dependence and substance abuse. The diagnostic criteria for each are presented below.

Substance Dependence

A maladaptive pattern of substance use, leading to clinically significant impairment or distress, as manifested by three (or more) of the following, occurring at any time in the same 12-month period:

1. Tolerance, as defined by either of the following:

1. A need for markedly increased amounts of the substance to achieve intoxication or desired effect; or
2. Markedly diminished effect with continued use of the same amount of the substance

2. Withdrawal, as manifested by either of the following:

1. The characteristic withdrawal syndrome for the substance; or
2. The same (or a closely related) substance is taken to relieve or avoid withdrawal symptoms

3. The substance is often taken in larger amounts or over a longer period than was intended
4. There is a persistent desire or unsuccessful efforts to cut down or control substance use
5. A great deal of time is spent on activities necessary to obtain the substance (e.g., visiting multiple doctors or driving long distances), use the substance (e.g., chain-smoking), or recover from its effects
6. Important social, occupational, or recreational activities are given up or reduced because of substance use
7. The substance use is continued despite knowledge of having a persistent physical or psychological problem that is likely to have been caused or exacerbated by the substance (e.g., current cocaine use despite recognition of cocaine-induced depression, or continued drinking despite recognition that an ulcer was made worse by alcohol consumption).

Substance Abuse

A maladaptive pattern of substance use leading to clinically significant impairment or distress, as manifested by one (or more) of the following, occurring within a 12-month period:

1. Recurrent substance use resulting in a failure to fulfil major role obligations at work, school, or home (e.g., repeated absences or poor work performance related to substance use; substance‐related absences, suspensions, or expulsions from school; neglect of children or household)
2. Recurrent substance use in situations in which it is physically hazardous (e.g., driving an automobile or operating a machine when impaired by substance use)
3. Recurrent substance‐related legal problems (e.g., arrests for substance‐related disorderly conduct)
4. Continued substance use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of the substance (e.g., arguments with spouse about consequence of intoxication, physical fights).

DSM-5 Diagnostic Criteria

According to the DSM-5, there is one main methamphetamine-related mental health disorder: a stimulant use disorder. This is defined as:

A pattern of amphetamine-type substance, cocaine, or other stimulant use leading to clinically significant impairment or distress, as manifested by at least two of the following, occurring within a 12-month period:

1. The stimulant is often taken in larger amounts or over a longer period than was intended
2. There is a persistent desire or unsuccessful efforts to cut down or control stimulant use
3. A great deal of time is spent in activities necessary to obtain the stimulant, use the stimulant, or recover from its effects
4. Craving, or a strong desire or urge to use the stimulant
5. Recurrent stimulant use resulting in a failure to fulfil major role obligations at work, school, or home
6. Continued stimulant use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of the stimulant
7. Important social, occupational, or recreational activities are given up or reduced because of stimulant use
8. Recurrent stimulant use in situations in which it is physically hazardous
9. Stimulant use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by the stimulant
10. Tolerance, as defined by either of the following:
    1. A need for markedly increased amounts of the stimulant to achieve intoxication or desired effect.
    2. A markedly diminished effect with continued use of the same amount of the stimulant.

Note: This criterion is not considered to be met for those taking stimulant medications solely under appropriate medical supervision, such as medications for attention-deficit/hyperactivity disorder or narcolepsy.

    11.  Withdrawal, as manifested by either of the following:

1. The characteristic withdrawal syndrome for the stimulant (refer to Criteria A and B of the criteria set for stimulant withdrawal, p. 569).
2. The stimulant (or a closely related substance) is taken to relieve or avoid withdrawal symptoms.

Note: This criterion is not considered to be met for those taking stimulant medications solely under appropriate medical supervision, such as medications for attention-deficit/hyperactivity disorder or narcolepsy.

A mild stimulant use disorder is defined as the presence of 2-3 of the above symptoms.

A moderate stimulant use disorder is defined as the presence of 4-5 of the above symptoms.

A severe stimulant use disorder is defined as the presence of 6 or more of the above symptoms.

Almost two percent (1.9%) of the Australian population have met the diagnostic criteria for stimulant^† abuse in their lifetime, and 1.4% have met the diagnostic criteria for stimulant dependence.

Approximately 0.3% of the Australian population have met the diagnostic criteria for stimulant^† abuse in the past 12 months, and 0.3%* have met the diagnostic criteria for stimulant dependence.

In 2011, methamphetamine was used prior to 105 drug-induced deaths in Australia. Methamphetamine was determined to be the underlying cause of death in 23 of these cases.

The majority of methamphetamine-related deaths were experienced by Australians aged 15-54 years (n=101). In 21 of these cases, methamphetamine was determined to be the underlying cause of death.

The rate of methamphetamine-related deaths among Australians aged 15-54 years has increased between 2010 and 2011. In 2010 there were 7.1 methamphetamine-related deaths per million persons, compared to 8.1 deaths per million persons in 2011.