Drug Dependence

Also known as:  Psychoactive Substance Dependence

Drug Dependence is a deliberately vague term that encompasses parts of or all of the following states that arise from repeated administration of a psychoactive drug on a periodic or continuous basis in order to derive physical or psychological well-being:

The American Psychiatric Association defines Drug Dependence as “a cluster of cognitive, behavioral and physiologic symptoms that indicate that a person has impaired control of psychoactive substance use and continues use of the substance despite adverse consequences”.

Substances that cause Psychological Dependence usually do so by activating specific circuits within the Brain - these circuits are dedicated to the mediation of Reward and Pleasure.  The activation of these Reward mechanisms (in the Hypothalamus and Limbic System) appears to be the single feature shared by all substances that are capable of causing Drug Dependence.

Nervous System

 Substances that provide relief from Anxiety are capable of causing Drug Dependence.

 Substances that induce Euphoria are generally capable of causing Drug Dependence (due to positive reinforcement).

 All substances capable of causing Drug Dependence (through varied mechanisms and Neurotransmitters) ultimately stimulate the Nucleus Accumbens - a component of the Dopaminergic System and Limbic System that traverses the medial Forebrain bundle.

Alkaloids

 Nicotine has strong potential to cause Drug Dependence (e.g. cigarette smokers).  ^[1]

Methylxanthines

 Caffeine (in dosages of more than 600 mg per day = 6 cups of Coffee) may cause Drug Dependence (including a Caffeine withdrawal syndrome characterized by Irritability, Lethargy and Headache).

Prescribed Medications

 Barbiturates may cause Drug Dependence (primarily Psychological Dependence but also Physical Dependence following long term treatment using doses of 40 mg or more per day).

 Benzodiazepines may cause Drug Dependence.  ^[2]