Common symptoms include:

- Sudden changes in behaviour – may engage in secretive or suspicious behaviour

- Mood changes – anger towards others, paranoia and little care shown about themselves or their future

- Problems with work or school – lack of attendance

- Changes in eating and sleeping habits

- Changes in friendship groups and poor family relationships

- A sudden unexplained change in financial needs – leading to borrowing/stealing money

There are many more symptoms such as physical and psychological changes, though this is often dependent on which drug is being abused. It is, however, common that abusers will experience unpleasant withdrawal symptoms if the drug is taken away from them.

It is also reported that others have strong cravings even after they have not used the drug for a long period of time. This is called being "clean". To determine how the brain triggers these cravings, multiple tests have been done on mice. It is also now thought that these cravings can be explained by substance-related disorders as a subcategory of personality disorders as classified by the DSM-5.

Substance abuse, also known as drug abuse, is a patterned use of a substance (drug) in which the user consumes the substance in amounts or with methods which are harmful to themselves or others.

The drugs used are often associated with levels of intoxication that alter judgment, perception, attention and physical control, not related with medical or therapeutic effects. It is often thought that the main abused substances are illegal drugs and alcohol; however it is becoming more common that prescription drugs and tobacco are a prevalent problem.

Substance-related disorders, including both substance dependence and substance abuse, can lead to large societal problems. It is found to be greatest in individuals ages 18–25, with a higher likelihood occurring in men compared to women, and urban residents compared to rural residents. On average, general medical facilities hold 20% of patients with substance-related disorders, possibly leading to psychiatric disorders later on. Over 50% of individuals with substance-related disorders will often have a "dual diagnosis," where they are diagnosed with the substance abuse, as well as a psychiatric diagnosis, the most common being major depression, personality disorder, anxiety disorders, and dysthymia.

From the ICD-9 database:

- A chronic disease in which a person craves drinks that contain alcohol and is unable to control his or her drinking. A person with this disease also needs to drink greater amounts to get the same effect and has withdrawal symptoms after stopping alcohol use. Alcoholism affects physical and mental health, and can cause problems with family, friends, and work.

- A disorder characterized by a pathological pattern of alcohol use that causes a serious impairment in social or occupational functioning.

- A primary, chronic disease with genetic, psychosocial, and environmental factors influencing its development and manifestations. The disease is often progressive and fatal. It is characterized by impaired control over drinking, preoccupation with the drug alcohol, use of alcohol despite adverse consequences, and distortions in thinking, most notably denial. Each of these symptoms may be continuous or periodic. (morse & flavin for the joint commission of the national council on alcoholism and drug dependence and the american society of addiction medicine to study the definition and criteria for the diagnosis of alcoholism: in jama 1992;268:1012-4)

- For most adults, moderate alcohol use is probably not harmful. However, about 18 million adult Americans are alcoholics or have alcohol problems. Alcoholism is a disease with four main features:

- craving - a strong need to drink

- loss of control - not being able to stop drinking once you've started

- physical dependence - withdrawal symptoms, such as nausea, sweating, or shakiness when you don't drink

- tolerance - the need to drink greater amounts of alcohol to feel the same effect

- Temporary mental disturbance marked by muscle incoordination and paresis as the result of excessive alcohol ingestion.

According to the DSM-IV criteria for alcohol dependence, at least three out of seven of the following criteria must be manifest during a 12-month period:

- Tolerance

- Withdrawal symptoms or clinically defined alcohol withdrawal syndrome

- Use in larger amounts or for longer periods than intended

- Persistent desire or unsuccessful efforts to cut down on alcohol use

- Time is spent obtaining alcohol or recovering from effects

- Social, occupational and recreational pursuits are given up or reduced because of alcohol use

- Use is continued despite knowledge of alcohol-related harm (physical or psychological)

Physical dependence on a substance is defined by the appearance of characteristic physical withdrawal symptoms when the substance is suddenly discontinued. Opiates, benzodiazepines, barbiturates, alcohol and nicotine induce physical dependence. On the other hand, some categories of substances share this property and are still not considered addictive: cortisone, beta blockers and most antidepressants are examples.

Some substances induce physical dependence or physiological tolerance - but not addiction — for example many laxatives, which are not psychoactive; nasal decongestants, which can cause rebound congestion if used for more than a few days in a row; and some antidepressants, most notably venlafaxine, paroxetine and sertraline, as they have quite short half-lives, so stopping them abruptly causes a more rapid change in the neurotransmitter balance in the brain than many other antidepressants. Many non-addictive prescription drugs should not be suddenly stopped, so a doctor should be consulted before abruptly discontinuing them.

The speed with which a given individual becomes addicted to various substances varies with the substance, the frequency of use, the means of ingestion, the intensity of pleasure or euphoria, and the individual's genetic and psychological susceptibility. Some people may exhibit alcoholic tendencies from the moment of first intoxication, while most people can drink socially without ever becoming addicted. Opioid dependent individuals have different responses to even low doses of opioids than the majority of people, although this may be due to a variety of other factors, as opioid use heavily stimulates pleasure-inducing neurotransmitters in the brain. Nonetheless, because of these variations, in addition to the adoption and twin studies that have been well replicated, much of the medical community is satisfied that addiction is in part genetically moderated. That is, one's genetic makeup may regulate how susceptible one is to a substance and how easily one may become attached to a pleasurable routine.

Eating disorders are complicated pathological mental illnesses and thus are not the same as addictions described in this article. Eating disorders, which some argue are not addictions at all, are driven by a multitude of factors, most of which are highly different from the factors behind addictions described in this article. It has been reported, however, that patients with eating disorders can successfully be treated with the same non-pharmacological protocols used in patients with chemical addiction disorders.

Gambling is another potentially addictive behavior with some biological overlap. Conversely gambling urges have emerged with the administration of Mirapex (pramipexole), a dopamine agonist.

The obsolete term physical addiction is deprecated, because of its connotations. In modern pain management with opioids physical dependence is nearly universal. High-quality, long-term studies are needed to better delineate the risks and benefits of chronic opiate use.

The DSM definition of addiction can be boiled down to compulsive use of a substance (or engagement in an activity) despite ongoing negative consequences. The medical community makes a distinction between physical dependence (characterized by symptoms of physical withdrawal symptoms, like tremors and sweating) and psychological dependence (emotional-motivational withdrawal symptoms). Physical dependence is simply needing a substance to function. Humans are all physically dependent upon oxygen, food and water. A drug can cause physical dependence and not psychological dependence (for example, some blood pressure medications, which can produce fatal withdrawal symptoms if not tapered) and some can cause psychological dependence without physical dependence (the withdrawal symptoms associated with cocaine are all psychological, there is no associated vomiting or diarrhea as there is with opiate withdrawal).

There are several different screening tools that have been validated for use with adolescents such as the CRAFFT and adults such as the CAGE.

Dual diagnosis (also called co-occurring disorders, COD, or dual pathology) is the condition of suffering from a mental illness and a comorbid substance abuse problem. There is considerable debate surrounding the appropriateness of using a single category for a heterogeneous group of individuals with complex needs and a varied range of problems. The concept can be used broadly, for example depression and alcoholism, or it can be restricted to specify severe mental illness (e.g. psychosis, schizophrenia) and substance misuse disorder (e.g. cannabis abuse), or a person who has a milder mental illness and a drug dependency, such as panic disorder or generalized anxiety disorder and is dependent on opioids. Diagnosing a primary psychiatric illness in substance abusers is challenging as drug abuse itself often induces psychiatric symptoms, thus making it necessary to differentiate between substance induced and pre-existing mental illness.

Those with co-occurring disorders face complex challenges. They have increased rates of relapse, hospitalization, homelessness, and HIV and hepatitis C infection compared to those with either mental or substance use disorders alone. The cause of co-occurring disorders is unknown, although there are several theories.

Symptoms can sometimes come and go with wave-like reoccurrences or fluctuations in severity of symptoms. Common symptoms include impaired cognition, irritability, depressed mood, and anxiety; all of which may reach severe levels which can lead to relapse.

The protracted withdrawal syndrome from benzodiazepines can produce symptoms identical to generalized anxiety disorder as well as panic disorder. Due to the sometimes prolonged nature and severity of benzodiazepine withdrawal, abrupt withdrawal is not advised.

Common symptoms of post-acute withdrawal syndrome are:

- Psychosocial dysfunction

- Anhedonia

- Depression

- Impaired interpersonal skills

- Obsessive-compulsive behaviour

- Feelings of guilt

- Autonomic disturbances

- Pessimistic thoughts

- Impaired concentration

- Lack of initiative

- Craving

- Inability to think clearly

- Memory problems

- Emotional overreactions or numbness

- Sleep disturbances

- Physical coordination problems

- Stress sensitivity

- Increased sensitivity to pain

- Panic disorder

- Generalized anxiety disorder

- Sleep disturbance (dreams of using, behaviors associated with the life style)

Symptoms occur intermittently, but are not always present. They are made worse by stress or other triggers and may arise at unexpected times and for no apparent reason. They may last for a short while or longer. Any of the following may trigger a temporary return or worsening of the symptoms of post-acute withdrawal syndrome:

- Stressful and/or frustrating situations

- Multitasking

- Feelings of anxiety, fearfulness or anger

- Social conflicts

- Unrealistic expectations of oneself

Stimulant use disorder is a type of substance use disorder that involves the abuse of stimulants. It is defined in the DSM-5 as "the continued use of amphetamine-type substances, cocaine, or other stimulants leading to clinically significant impairment or distress, from mild to severe." These psychoactive drugs, known as stimulants, are the most widely used drugs in the world today. Approximately 200 million Americans have used some type of a stimulant in the past year alone.

Substance abuse, also known as drug abuse, is a patterned use of a drug in which the user consumes the substance in amounts or with methods which are harmful to themselves or others, and is a form of substance-related disorder. Widely differing definitions of drug abuse are used in public health, medical and criminal justice contexts. In some cases criminal or anti-social behavior occurs when the person is under the influence of a drug, and long term personality changes in individuals may occur as well. In addition to possible physical, social, and psychological harm, use of some drugs may also lead to criminal penalties, although these vary widely depending on the local jurisdiction.

Drugs most often associated with this term include: alcohol, cannabis, barbiturates, benzodiazepines, cocaine, methaqualone, opioids and some substituted amphetamines. The exact cause of substance abuse is not clear, with the two predominant theories being: either a genetic disposition which is learned from others, or a habit which if addiction develops, manifests itself as a chronic debilitating disease.

In 2010 about 5% of people (230 million) used an illicit substance. Of these 27 million have high-risk drug use otherwise known as recurrent drug use causing harm to their health, psychological problems, or social problems or puts them at risk of those dangers. In 2015 substance use disorders resulted in 307,400 deaths, up from 165,000 deaths in 1990. Of these, the highest numbers are from alcohol use disorders at 137,500, opioid use disorders at 122,100 deaths, amphetamine use disorders at 12,200 deaths, and cocaine use disorders at 11,100.

Not all mental health professionals agree about standard methods of treatment. Caring for an individual with a physical addiction is not necessarily treating a pathology. The caregiver may only require assertiveness skills and the ability to place responsibility for the addiction on the other. There are various recovery paths for individuals who struggle with codependency. For example, some may choose cognitive-behavioral psychotherapy, sometimes accompanied by chemical therapy for accompanying depression. There also exist support groups for codependency, such as Co-Dependents Anonymous (CoDA), Al-Anon/Alateen, Nar-Anon, and Adult Children of Alcoholics (ACoA), which are based on the twelve-step program model of Alcoholics Anonymous and Celebrate Recovery a Christian, Bible-based group. Many self-help guides have been written on the subject of codependency.

Sometimes an individual can, in attempts to recover from codependency, go from being overly passive or overly giving to being overly aggressive or excessively selfish. Many therapists maintain that finding a balance through healthy assertiveness (which leaves room for being a caring person and also engaging in healthy caring behavior) is true recovery from codependency and that becoming extremely selfish, a bully, or an otherwise conflict-addicted person is not. Developing a permanent stance of being a victim (having a victim mentality) would also not constitute true recovery from codependency and could be another example of going from one extreme to another. A victim mentality could also be seen as a part of one's original state of codependency (lack of empowerment causing one to feel like the "subject" of events rather than being an empowered actor). Someone truly recovered from codependency would feel empowered and like an author of their life and actions rather than being at the mercy of outside forces. A victim mentality may also occur in combination with passive–aggressive control issues. From the perspective of moving beyond victim-hood, the capacity to forgive and let go (with exception of cases of very severe abuse) could also be signs of real recovery from codependency, but the willingness to endure further abuse would not.

Unresolved patterns of codependency can lead to more serious problems like alcoholism, drug addiction, eating disorders, sex addiction, psychosomatic illnesses, and other self-destructive or self-defeating behaviors. People with codependency are also more likely to attract further abuse from aggressive individuals, more likely to stay in stressful jobs or relationships, less likely to seek medical attention when needed and are also less likely to get promotions and tend to earn less money than those without codependency patterns. For some people, the social insecurity caused by codependency can progress into full-blown social anxiety disorders like social phobia, avoidant personality disorder or painful shyness. Other stress-related disorders like panic disorder, depression or PTSD may also be present.

Disturbances in mental function can persist for several months or years after withdrawal from benzodiazepines. Psychotic depression persisting for more than a year following benzodiazepine withdrawal has been documented in the medical literature. The patient had no prior psychiatric history. The symptoms reported in the patient included, major depressive disorder with psychotic features, including persistent depressed mood, poor concentration, decreased appetite, insomnia, anhedonia, anergia and psychomotor retardation. The patient also experienced paranoid ideation (believing she was being poisoned and persecuted by co-employees), accompanied by sensory hallucinations. Symptoms developed after abrupt withdrawal of chlordiazepoxide and persisted for 14 months. Various psychiatric medications were trialed which were unsuccessful in alleviating the symptomatology. Symptoms were completely relieved by recommending chlordiazepoxide for irritable bowel syndrome 14 months later. Another case report, reported similar phenomenon in a female patient who abruptly reduced her diazepam dosage from 30 mg to 5 mg per day. She developed electric shock sensations, depersonalisation, anxiety, dizziness, left temporal lobe EEG spiking activity, hallucinations, visual perceptual and sensory distortions which persisted for years.

A clinical trial of patients taking the benzodiazepine alprazolam (Xanax) for as little as 8 weeks triggered protracted symptoms of memory deficits which were still present after up to 8 weeks post cessation of alprazolam.

Include the following:

- Depression

- Shaking

- Feeling unreal

- Appetite loss

- Muscle twitching

- Memory loss

- Motor impairment

- Nausea

- Muscle pains

- Dizziness

- Apparent movement of still objects

- Feeling faint

- Noise sensitivity

- Light sensitivity

- Peculiar taste

- Pins and needles

- Touch sensitivity

- Sore eyes

- Hallucinations

- Smell sensitivity

All sedative-hypnotics, e.g. alcohol, barbiturates, benzodiazepines and the nonbenzodiazepine Z-drugs have a similar mechanism of action, working on the GABA receptor complex and are cross tolerant with each other and also have abuse potential. Use of prescription sedative-hypnotics; for example the nonbenzodiazepine Z-drugs often leads to a relapse back into substance misuse with one author stating this occurs in over a quarter of those who have achieved abstinence.

Public health practitioners have attempted to look at substance use from a broader perspective than the individual, emphasizing the role of society, culture, and availability. Some health professionals choose to avoid the terms alcohol or drug "abuse" in favor of language they consider more objective, such as "substance and alcohol type problems" or "harmful/problematic use" of drugs. The Health Officers Council of British Columbia — in their 2005 policy discussion paper, "A Public Health Approach to Drug Control in Canada]" — has adopted a public health model of psychoactive substance use that challenges the simplistic black-and-white construction of the binary (or complementary) antonyms "use" vs. "abuse". This model explicitly recognizes a spectrum of use, ranging from beneficial use to chronic dependence.

Research data indicates that steroids affect the serotonin and dopamine neurotransmitter systems of the brain. In an animal study, male rats developed a conditioned place preference to testosterone injections into the nucleus accumbens, an effect blocked by dopamine antagonists, which suggests that androgen reinforcement is mediated by the brain. Moreover, testosterone appears to act through the mesolimbic dopamine system, a common substrate for drugs of abuse. Nonetheless, androgen reinforcement is not comparable to that of cocaine, nicotine, or heroin. Instead, testosterone resembles other mild reinforcers, such as caffeine, or benzodiazepines. The potential for androgen addiction remains to be determined.

Anabolic steroids are not psychoactive and cannot be detected by stimuli devices like a pupilometer which makes them hard to spot as a source of neuropsychological imbalaces in some AAS users.

Substance dependence also known as drug dependence is an adaptive state that develops from repeated drug administration, and which results in withdrawal upon cessation of drug use. A "drug addiction", a distinct concept from substance dependence, is defined as compulsive, out-of-control drug use, despite negative consequences. An "addictive drug" is a drug which is both rewarding and reinforcing. ΔFosB, a gene transcription factor, is now known to be a critical component and common factor in the development of virtually all forms of behavioral addiction and drug addictions, but not dependence.

Within the framework of the 4th edition of the "Diagnostic and Statistical Manual of Mental Disorders" ("DSM-IV"), substance dependence is redefined as a drug addiction, and can be diagnosed without the occurrence of a withdrawal syndrome. It is now described accordingly: "When an individual persists in use of alcohol or other drugs despite problems related to use of the substance, substance dependence may be diagnosed. Compulsive and repetitive use may result in tolerance to the effect of the drug and withdrawal symptoms when use is reduced or stopped. This, along with Substance Abuse are considered Substance Use Disorders."

Timmen Cermak, M.D., proposed that co‐dependency be listed as a personality disorder in the Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R; American Psychiatric Association, 1987). Cermak reasoned that when specific personality traits become excessive and maladaptive and caused significant impairment in functioning or caused significant distress, it warrants a personality disorder diagnosis.

Cermak proposed the following criteria for this disorder:

1. Continued investment of self-esteem in the ability to control both oneself and others in the face of serious adverse consequences.

2. Assumption of responsibility for meeting others' needs to the exclusion of acknowledging one's own.

3. Anxiety and boundary distortions around intimacy and separation.

4. Enmeshment in relationships with personality disordered, chemically dependent, other co ‐ dependent, and/or impulse ‐ disordered individuals.

5. Three or more of the following:

1. Excessive reliance on denial

2. Constriction of emotions (with or without dramatic outbursts)

3. Depression

4. Hypervigilance

5. Compulsions

6. Anxiety

7. Substance abuse

8. Has been (or is) the victim of recurrent physical or sexual abuse

9. Stress ‐ related medical illnesses

10. Has remained in a primary relationship with an active substance abuser for at least two years without seeking outside help.

Withdrawal is the body's reaction to abstaining from a substance upon which a person has developed a dependence syndrome. When dependence has developed, cessation of substance use produces an unpleasant state, which promotes continued drug use through negative reinforcement; i.e., the drug is used to escape or avoid re-entering the associated withdrawal state. The withdrawal state may include physical-somatic symptoms (physical dependence), emotional-motivational symptoms (psychological dependence), or both. Chemical and hormonal imbalances may arise if the substance is not introduced. Psychological stress may also result if the substance is not re-introduced.

Infants also suffer from substance withdrawal, known as Neonnatal Abstinence Syndrome (NAS) which has severe and life-threatening effects on growing fetus. Addiction to drugs and alcohol in expecting mothers does not only cause NAS but also an array of other issues which can continually affect the infant throughout his/her lifetime. The type of drug which was abused during the months of pregnancy has many different effects on the child which can affect the infant in many ways throughout his/her life.

Amphetamine dependence refers to a state of psychological dependence on a drug in the amphetamine class. In individuals with substance use disorder (problematic use or abuse with dependence), psychotherapy is currently the best treatment option as no pharmacological treatment has been approved. Tolerance is expected to develop with regular substituted amphetamine use. When substituted amphetamines are abused, drug tolerance develops rapidly.

Severe withdrawal associated with dependence from recreational substituted amphetamine use can be difficult for a user to cope with. Long-term use of certain substituted amphetamines, particularly methamphetamine, can reduce dopamine activity in the brain. Psychostimulants that increase dopamine and mimic the effects of substituted amphetamines, but with lower abuse liability, could theoretically be used as replacement therapy in amphetamine dependence. However, the few studies that used amphetamine, bupropion, methylphenidate and modafinil as a replacement therapy did not result in less methamphetamine use or craving.

In 2013, overdose on amphetamine, methamphetamine, and other compounds implicated in an "amphetamine use disorder" resulted in an estimated 3,788 deaths worldwide (3,425–4,145 deaths, 95% confidence).

Individuals with an alcohol use disorder will often complain of difficulty with interpersonal relationships, problems at work or school, and legal problems. Additionally, people may complain of irritability and insomnia. Alcohol abuse is also an important cause of chronic fatigue.

Signs of alcohol abuse are related to alcohol's effects on organ systems. However, while these findings are often present, they are not necessary to make a diagnosis of alcohol abuse. Signs of alcohol abuse show its drastic effects on the central nervous system, including inebriation and poor judgment; chronic anxiety, irritability, and insomnia. Alcohol's effects on the liver include elevated liver function tests (classically AST is at least twice as high as ALT). Prolonged use leads to cirrhosis and liver failure. With cirrhosis, patients develop an inability to process hormones and toxins. The skin of a patient with alcoholic cirrhosis can feature cherry angiomas, palmar erythema and — in acute liver failure — jaundice and ascites. The derangements of the endocrine system lead to the enlargement of the male breasts. The inability to process toxins leads to liver disease, such as hepatic encephalopathy.

Alcohol abuse can result in brain damage which causes impairments in executive functioning such as impairments to working memory, visuospatial skills, and can cause an abnormal personality as well as affective disorders to develop. Binge drinking is associated with individuals reporting fair to poor health compared to non-binge drinking individuals and which may progressively worsen over time. Alcohol also causes impairment in a person's critical thinking. A person's ability to reason in stressful situations is compromised, and they seem very inattentive to what is going on around them. Social skills are significantly impaired in people suffering from alcoholism due to the neurotoxic effects of alcohol on the brain, especially the prefrontal cortex area of the brain. The social skills that are impaired by alcohol abuse include impairments in perceiving facial emotions, difficulty with perceiving vocal emotions and theory of mind deficits; the ability to understand humour is also impaired in alcohol abusers. Adolescent binge drinkers are most sensitive to damaging neurocognitive functions especially executive functions and memory. People who abuse alcohol are less likely to survive critical illness with a higher risk for having sepsis and were more likely to die during hospitalization.

A psychoactive drug, such as a stimulant, is a chemical or substance that effects one’s behavior, mind, and body. A stimulant can be smoked, injected, snorted, taken in pill form, chewed and even ingested in the form of a drink. Synthetic stimulants are becoming increasingly popular as users attempt to alter the chemicals in drugs to create different reactions, and ultimately steer clear of jail time, legal penalties and detection in drug screening efforts.

If a substance is used over a long period of time and the user becomes dependent upon it, a substance abuse issue begins to appear. Substance abuse may lead to substance dependence and with time, addiction. Both mental and physiological dependence requires the development of tolerance leading to withdrawal symptoms. Stimulants come in a very large variety of subtypes and among the most common are caffeine, nicotine, cocaine, methamphetamine, amphetamines, amphetamine congeners, electronic cigarettes, diet pills, plant stimulants, energy drinks, and the ever-evolving designer stimulants such as bath salts. Caffeine and nicotine are the most popular stimulants used today, with roughly 400 million cups of coffee consumed daily and 36.5 million current cigarette smokers, according to a 2015 study conducted by the Centers for Disease Control and Prevention. Nicotine, however, is treated separately psychiatrically under tobacco use disorder.

The identification of substance-induced versus independent psychiatric symptoms or disorders has important treatment implications and often constitutes a challenge in daily clinical practice. Similar patterns of comorbidity and risk factors in individuals with substance induced disorder and those with independent non-substance induced psychiatric symptoms suggest that the two conditions may share underlying etiologic factors.

Drug abuse, including alcohol and prescription drugs, can induce symptomatology which resembles mental illness, which can make it difficult to differentiate between substance induced psychiatric syndromes and pre-existing mental health problems. More often than not psychiatric disorders among drug or alcohol abusers disappear with prolonged abstinence. Substance induced psychiatric symptoms can occur both in the intoxicated state and also during the withdrawal state. In some cases these substance induced psychiatric disorders can persist long after detoxification, such as prolonged psychosis or depression after amphetamine or cocaine abuse. Abuse of hallucinogens can trigger delusional and other psychotic phenomena long after cessation of use and cannabis may trigger panic attacks during intoxication and with use it may cause a state similar to dysthymia. Severe anxiety and depression are commonly induced by sustained alcohol abuse which in most cases abates with prolonged abstinence. Even moderate sustained use of alcohol may increase anxiety and depression levels in some individuals. In most cases these drug induced psychiatric disorders fade away with prolonged abstinence. A protracted withdrawal syndrome can also occur with psychiatric and other symptoms persisting for months after cessation of use. Benzodiazepines are the most notable drug for inducing prolonged withdrawal effects with symptoms sometimes persisting for years after cessation of use.

Prospective epidemiological studies do not support the hypotheses that comorbidity of substance use disorders with other psychiatric illnesses is primarily a consequence of substance abuse or dependence or that increasing comorbidity is largely attributable to increasing use of substances. Yet emphasis is often on the effects of substances on the brain creating the impression that dual disorders are a natural consequence of these substances. However addictive drugs or exposure to gambling will not lead to addictive behaviors or drug dependence in most individuals but only in vulnerable ones, although, according to some researchers, neuroadaptation or regulation of neuronal plasticity, and molecular changes, may alter gene expression in some cases and subsequently lead to substance use disorders.

Research instruments are also often insufficiently sensitive to discriminate between independent, true dual pathology, and substance-induced symptoms. Structured instruments, as Global Appraisal of Individual Needs - Short Screener-GAIN-SS and Psychiatric Research Interview for Substance and Mental Disorders for DSM-IV-PRISM, have been developed to increase the diagnostic validity. While structured instruments can help organize diagnostic information, clinicians must still make judgments on the origin of symptoms.

Alcohol abuse is a previous psychiatric diagnosis in which there is recurring harmful use of alcohol despite its negative consequences. In 2013 it was reclassified as alcohol use disorder (alcoholism) along with alcohol dependence. There are two types of alcohol abuse, those who have anti-social and pleasure-seeking tendencies, and those who are anxiety-ridden people who are able to go without drinking for long periods of time but are unable to control themselves once they start. Binge drinking is another form of alcohol abuse. According to surveys, the heaviest drinkers are the United Kingdom's adolescents. In 2013, 139,000 deaths globally were directly due to alcohol abuse and an additional 384,000 to cirrhosis from excess alcohol consumption.

Barbiturate dependence develops with regular use of barbiturates. This in turn may lead to a need for increasing doses of the drug to get the original desired pharmacological or therapeutic effect. Barbiturate use can lead to both addiction and physical dependence, and as such they have a high potential for abuse. Management of barbiturate dependence involves considering the affected person's age, comorbidity and the pharmacological pathways of barbiturates. Psychological addiction to barbiturates can develop quickly. The GABA receptor, one of barbiturates' main sites of action, is thought to play a pivotal role in the development of tolerance to and dependence on barbiturates, as well as the euphoric "high" that results from their abuse. The mechanism by which barbiturate tolerance develops is believed to be different from that of ethanol or benzodiazepines, even though these drugs have been shown to exhibit cross-tolerance with each other. The management of a physical dependence on barbiturates is stabilisation on the long-acting barbiturate phenobarbital followed by a gradual titration down of dose. The slowly eliminated phenobarbital lessens the severity of the withdrawal syndrome and reduces the chances of serious barbiturate withdrawal effects such as seizures. Antipsychotics are not recommended for barbiturate withdrawal (or other CNS depressant withdrawal states) especially clozapine, olanzapine or low potency phenothiazines e.g. chlorpromazine as they lower the seizure threshold and can worsen withdrawal effects; if used extreme caution is required.

The Diagnostic Statistical Manual IV (DSM IV) and the International Classification of Diseases, Volume 10 (ICD 10) differ in the way they regard Anabolic-Androgenic Steroids' (AAS) potential for producing dependence.

DSM IV regards AAS as potentially dependence producing. ICD 10 however regards them as non-dependence producing. Anabolic steroids are not physically addictive but users can develop a psychological dependence on the physical result.