Substance-Related Disorders

Substance-related disorders involve drugs that directly activate the brain's reward system. The activation of the reward system typically causes feelings of pleasure; the specific pleasurable feelings evoked vary widely depending on the drug. These drugs are divided into 10 different classes that have different, although not completely distinct, pharmacologic mechanisms. The classes of drugs include

This classification is not based on whether a drug is legal (eg, alcohol, caffeine), illegal (eg, hallucinogens), or available by prescription (eg, morphine, lorazepam)..

Substance abuse, or drug abuse, is the consumption of a drug or drugs in ways and/or quantities which cause harm to the person consuming them and/or to others. Substance dependence, meanwhile, is a condition which occurs as a result of the repeated consumption of a specific substance of abuse, in which the system of an individual adapts to the presence of the drug and builds a tolerance to it, requiring further consumption of substance in order for the individual to feel “normal”; if the affected person stops taking the drug, various negative symptoms may manifest in a condition known as withdrawal syndrome, which will last until the person system has readjusted to the absence of the drug (although some symptoms may persist for a long time after cessation of use).

Substance-induced disorders are medical conditions directly caused by substance use and/or abuse. The most obvious substance-induced disorder (though one which most laypersons may not recognize as a disorder at all) is intoxication; other substance-induced disorders include withdrawal, substance-induced mood disorders, substance-induced delirium, and substance-induced psychosis.

Symptoms of Substance-Related Disorder:

One of the most obvious symptoms of substance abuse – whether or not as a component of an addiction – is intoxication. The nature of intoxication differs substantially from one substance of abuse to another – for example, stimulants such as cocaine typically provoke feelings of invigoration which cause an individual under the influence to behave very energetically, while at the other extreme cannabis or opioids may cause someone taking them to be very lethargic and sluggish – but regardless of how it manifests, intoxication typically results in changes (often noticeable ones) from normal behavior.

The behavioral changes resulting from intoxication will only be temporary, and the affected individual’s behavior is likely to revert to normal once the substance wears off (though there may be after-effects in the form of hangover or comedown which may also affect behavior). However, long-term substance abuse may result in more permanent behavioral changes.

  • An individual’s clothing style, mannerisms, and vocabulary may change as a result of their exposure to drug-taking subcultures and their spending time with new peer groups.

  • They may be more prone to risk-taking behaviors, and may even begin to engage in criminal activity.

  • They may become secretive and furtive as they seek to conceal their drug abuse from family members and friends.

  • They may display regular mood swings.

  • Previously enjoyed activities and hobbies may be engaged in less and less, and eventually dropped altogether.

  • Changes in eating and sleeping habits may be noticeable.

  • Poor concentration and absenteeism may affect work or academic performance.

  • Relationships with partners, family, and friends may be neglected or may suffer due to arguments.

  • Financial circumstances may suffer; the individual may frequently ask to borrow money, may end up in large amounts of debt, and may even resort to criminal activity to try and obtain money.

A great many health issues – physical and mental – can also result from long-term drug abuse (see below), and some of these may have visible symptoms that can be identified by observers.

All the above symptoms may manifest without an individual actually becoming addicted to their drug/s of choice, though drug consumption over a prolonged period which is sufficient to cause many of these symptoms is extremely likely to lead to addiction and dependence. If this is the case, as well as the symptoms listed above the individual may well experience bouts of withdrawal if and when they are unable to obtain the drug/s on which they have become dependent.

Withdrawal symptoms may vary significantly from one drug to the next, but are likely to manifest within one or two days of cessation of use and to last between one and two weeks (though some symptoms may persist long afterward); if an individual is observed to display withdrawal symptoms on various occasions, they may well have a long-term substance dependence disorder. Some symptoms typically associated with withdrawal include cravings; nausea; headaches; heart palpitations; diarrhea; muscle cramps; tremors; twitches; sweating; difficulty breathing; insomnia; anxiety; poor concentration; irritability; restlessness; panic attacks; lack of appetite; anorgasmia; low libido; and depression. Withdrawal from some substances, including alcohol and benzodiazepines, can be fatal.