Substance Use Disorders – What are they?

There are several different kinds of substances, both legal and illegal, that have the potential to cause addiction, abuse, and dependency. If someone develops a physical or mental dependence on one of these substances, they may be diagnosed with a substance use disorder. Treatment can include medication and therapeutic intervention. 

Types of substance use disorders

According to the Diagnostic and Statistical Manual of Mental Disorders, 5^th edition (DSM-5), substance use disorders can include the use of 10 types of legal and illegal substances ^[1][2]:

• Alcohol
• Caffeine
• Tobacco
• Cannabis
• Hallucinogens, including LSD, mushrooms, and PCP
• Inhalants, including glue or paint thinners
• Opioids, including prescribed medications such as oxycodone and codeine, and illicit drugs such as heroin
• Sedatives, including hypnotics, sleep medications, and anti-anxiety medications
• Stimulants, including cocaine and methamphetamine
• Other substances, such as steroids and synthetic drugs

Symptoms of substance use disorders may vary slightly depending on the substance and severity, but can include ^[3][4][5]:

• Regular use of the substance, spending increasing amounts of time intoxicated. This might include beginning use earlier and continuing throughout the day.
• Thinking about reducing or stopping use of the substance and making attempts at quitting but being unsuccessful and returning to regular use.
• Using a prescribed medication or illegal substance more often than has been prescribed or continuing to take it after the advised length of time.
• Being unable to focus on work, hobbies, or conversations because of thinking about using the substance, how and when to obtain more, or being in a state of intoxication.
• Choosing to miss out on activities or social interactions to instead stay at home and use the substance.
• Neglecting wellbeing because of regular intoxication, such as forgetting to eat or shower, forgetting to pay rent or bills, or missing appointments or work.
• What used to be recreational use amongst friends turns into regular use alone.
• No longer feeling the effect of the substance to the same degree, so using more and more, to try and feel the same level of intoxication. This is called tolerance.
• Losing friends or relationships because of substance use.
• Entering dangerous situations in order to obtain or use the substance, such as meeting strangers at night to buy illicit drugs or driving while intoxicated.
• Noticing physical or mental harm occurring due to substance use but continuing regardless. For example, excessive stomach pain or sickness from ingestion, decaying teeth from smoking, or injection sites showing signs of infection.
• Changes in mood and behavior, such as depression, agitation, or aggression, particularly when asked about substance use.

Substance use and co-occurring mental disorders

Many people with a substance use disorder also have a co-existing mental health condition, such as depression, anxiety, or posttraumatic stress disorder (PTSD) ^[6].

In some cases, the mental illness leads to substance use, and in others, the substance use leads to the development of a mental illness. Some people may have genetic or environmental risk factors that increase their risk of both substance use disorders and mental illness ^[7].

Substance-induced conditions 

Depression, anxiety, and psychosis are common conditions that can be caused by the use or withdrawal of certain substances ^[8]. For example, substance-induced psychosis is a known disorder that is often caused by excessive or early cannabis use ^[6].  

Diagnostic criteria for substance-induced conditions includes ^[1][8]: 

• The symptoms were not present prior to the substance use
• The symptoms are present even when not in a state of intoxication from the substance
• The symptoms emerged within one month of the use or withdrawal of the substance

Substance use caused by mental illness or shared risk factors

There are several mental health conditions that commonly co-occur with substance use disorders that are thought to precede or cause substance abuse, including ^[6][7]: 

• PTSD
• Anxiety
• Depression
• Bipolar Disorder
• Personality Disorders
• Schizophrenia
• Attention deficit hyperactivity disorder (ADHD)

Research indicates that around a quarter of people with a serious mental illness, such as schizophrenia and bipolar disorder, also have a substance use disorder. People diagnosed with schizophrenia are significantly more likely than those without a mental health diagnosis to excessively use tobacco, alcohol, and illicit drugs ^[6]. 

Mental illness has also been shown to significantly increase the risk of prescription medication abuse, potentially leading to addiction. There is also research to suggest that those with a mental disorder in childhood are at increased risk of developing a substance use disorder ^[5][6]. 

Risk factors may be linked, such as genetic or environmental factors increasing the risk of mental illness as well as the risk of substance use disorder ^[5][7].

Many people with a mental health condition use substances as a way to temporarily avoid or alter their mental state, such as creating a euphoric feeling, numbing thoughts and feelings, or reducing agitation. However, substance use commonly worsens symptoms in the long-term and can create further mental and physical health issues ^[7][8]. 

How are substance use disorders diagnosed?

A diagnosis of substance use disorder may occur if the individual seeks professional support in reducing their use, if a family member expresses concern, or if a doctor notices concerning signs at a routine appointment that cause them to suspect a substance use disorder, such as poor hygiene, weight loss, red eyes, needle marks, or changes in mood or behavior ^[8].

Criteria in the DSM-5 for a diagnosis of substance use disorder involve aspects such as level of control over use, level of impairment, risky behaviors, and physiological signs of dependence ^[1][2]. 

For a diagnosis of substance use disorder, at least 2 of the following criteria must be met ^[1]: 

• Increasing amounts of the substance being used and for increasing periods of time
• Unsuccessful attempts to reduce or stop use, despite wanting to
• Obtaining, using, or recovering from the substance takes up a large proportion of time
• Regular cravings for the substance
• Impairments in professional, academic, or independent functioning
• Impact on interpersonal relationships and social abilities
• Avoidance of social or professional events and activities to spend time using
• Using the substance in unsafe places
• Being aware of the mental or physical effects of the substance but continuing use regardless
• Developing a tolerance to the substance
• Withdrawal symptoms when doses are reduced or stopped, relating to physical or mental dependence

The severity of the diagnosis depends on the number of criteria that are met. Substance use disorder can be classified as mild with 2-3 criteria, moderate with 4-5 criteria, and severe with 6 or more criteria being met ^[1][5]. 

How are substance use disorders treated?

The treatment for a substance use disorder will vary depending on the substance that is being used and the severity of the condition. Several treatment options are available.

Medication

Certain medications can be prescribed in order to help reduce withdrawal symptoms, detoxify, or replace a substance ^[9][10]:

• Alcohol: Disulfiram and naltrexone are medications that have been shown to help prevent alcohol consumption. Short-term use of benzodiazepines may also be prescribed while reducing alcohol consumption, to help reduce withdrawal symptoms.
• Opioids: Methadone and buprenorphine are commonly used medications in the treatment of opioid use disorders and dependence. These medications can help to reduce cravings and help people stay committed to recovery.
• Tobacco: Nicotine replacement therapy (NRT) is a helpful way to reduce cigarette use and includes various forms such as gum, inhalers, sprays, and patches. Varenicline is a medication that can be used short-term to aid in reducing smoking.

Antidepressants are also sometimes prescribed while treating substance use disorders, to help reduce emotional distress that can occur alongside withdrawal or in the context of co-occurring conditions ^[9].

Other substance use disorders, such as cocaine and methamphetamine, do not yet have approved medicinal treatments but there is ongoing research into the use of certain medications and their effectiveness ^[10].

Therapy

There are several types of therapy that can be useful in treating substance use disorders, particularly those that co-occur with other mental health conditions, such as ^[2][6][7]:

• CBT and DBT: Cognitive behavioral therapy and dialectical behavior therapy can help to reduce emotional distress, alter negative thoughts and behaviors, and teach positive coping strategies and skills to manage and reduce drug use.
• Family therapy: Children and adolescents may benefit from attending family therapy with their parents or guardians, while adults may benefit from attending family therapy with their partner or dependents, as this can provide an opportunity to develop positive communication, discuss and reduce harmful behaviors, and provide support to all involved.

Support groups

Many communities offer support groups that help people overcome their own addiction and maintain abstinence or offer guidance to those dealing with the effects of someone else’s addiction, by sharing experiences and support. Examples of this include:

• Alcoholics Anonymous
• Narcotics Anonymous
• Al-Anon
• Nar-Anon
• Alateen

Rehab or inpatient care

Some people choose or are advised to utilize a facility to help them detoxify from a substance, with the help of professional support. This can involve several weeks of staying at a residential facility or hospital, in which individual and group therapy will be offered, along with any required medicine and support to aid with the withdrawal and detoxification process. Treatment may begin with a medical detox program, followed by a transition into a residential treatment program, where the person participates in ongoing therapy and other addiction treatment services ^[2][10].

Treating co-occurring mental or physical health

If there is an underlying mental health condition contributing to the use of substances, the individual will likely be referred to a mental health specialist to treat this condition with the use of combined therapy and medication, alongside treatment for substance use disorder ^[7].

If there is a physical health condition, such as overdose, organ damage or failure, vitamin deficiency, or infection, the individual will be provided with appropriate treatment to manage this condition ^[2].