Types of Drug Dependence


The WHO expert committee has recognized that different groups of drugs produce different types of dependence and that the type should be specified.

The currently accepted types, the main classes of drugs involved and the clinical characteristics of the dependence are shown in Table Dependence types currently recognized and their clinical features.

Apart from noting the great variety of types that are now recognized, the majority of classes can be ignored for the purpose of the present paper and attention can be concentrated on the groups of ethanol and barbiturate/sedative. There are still divergent opinions on whether they should be grouped together, for both show psychological and physical dependence with virtually identical withdrawal reactions, or whether they should be separated. In favour of their being put into a single group is the extensive cross tolerance that can occur among drugs with similar actions, regardless of chemical structure, and the partial effectiveness of one group in ameliorating the withdrawal effects of the other.

Thus, for example, severe ethanol withdrawal reactions can be prevented by barbiturates, phenothiazines, benzodiazepines, chloral hydrate and paraldehyde. Conversely ethanol is partially effective in the prevention of barbiturate withdrawal phenomena.

Such sedatives, however, have no direct effect on the morphine-type withdrawal syndromes, although other members of that group can cross substitute (e.g. methadone for morphine).

Despite this evidence of cross substitution between ethanol and the barbiturate/sedatives it is probably wiser to regard them as separate groups at the present time, indeed with the great variation in-dependence liability that exists in the barbiturate/sedative group () subdivisions of this may also be necessary. This aspect of differences within the barbiturate/sedative group will be considered again later ().

Against this background of clearly recognized types of drug dependence we can examine the evidence for dependence on the benzodiazepines, try to determine whether it is related to any of the other types and attempt to estimate its incidence in normal clinical usage.

Table Dependence types currently recognized and their clinical features

Type Representative drugs Psychological dependence Clinical features of abstinence
Morphine type Morphine



Pethidine, etc.

Severe rapid psychological dependence with initial euphoria but later passivity and inertia.

Tolerance + +

Restlessness, rubbing the face and body, irritability, yawning, salivation, apprehension, nausea, vomiting, abdominal cramps, tremors, joint pains, running eyes and nose, diarrhoea and in later stages elevated blood pressure, raised blood sugar and spontaneous ejaculation or orgasm.
Cocaine type Cocaine Severe psychological dependence, mainly stimulant.

No true tolerance.

No physical dependence
Cannabis type Tetrahydrocannabinol Severe psychological dependence with deteriorated social behaviour, apathy, indolence and inertia.

No tolerance.

No physical dependence
Amphetamine type Amphetamine and related phenylethylamines Severe psychological dependence with excitement, restless irritability, repetitive overactivity and hallucinations.

Tolerance + +

? physical dependence see under psychological dependence
Hallucinogen type LSD




Psychological dependence with emotional lability, hallucinations and morbid deterioration of social behaviour.

Tolerance develops to most.

? physical dependence
Ethanol type All alcoholic beverages methylated spirit Psychological dependence of varying severity and rapidity of development. There is variation in early behaviour with later gross deterioration of social behaviour.

Tolerance +

Anxiety, sleeplessness, coarse tremors, weakness, abdominal cramps, hallucinations, disorientation. convulsions
Barbiturate / sedative type Barbiturates




Psychological dependence which varies in severity and rapidity of development between drugs and between patients.

Varying degrees of deterioration of social behaviour.

Tolerance common to most drugs.

Anxiety, insomnia, anorexia, nausea, vomiting, muscle twitching, delirium and convulsions
Tobacco Cigarettes, etc. Psychological dependence severe.

Tolerance present.

EEC and sleep changes. Reduced performance in some psychomotor tests
Caffeine Tea


? mild psychological dependence.

Some tolerance.

No physical dependence

A Broader Concept of ‘Psychotropics’

It has already been stressed () that there are few of us who do not resort to some form of ‘drug’, taking that term in its wide WHO definition, in a manner that must come broadly within the format of psychological dependence. That is to say there is an unnatural drive towards the ‘drug’ for a pleasure-seeking goal. For most of us of course the ‘drug’ concerned is one of the socially accepted beverages; tea, coffee or alcohol, although even within these socially accepted drinks a spectrum of dependence becomes immediately apparent with alcohol at the high-risk end.

Each of these substances can be classed as a psychotropic ‘drug’, again using the WHO definition for ‘drug’, for there is a mood change as a result of its ingestion.

It is important to realize that the concept of psychotropic can be extended beyond the realm of drugs for a broad range of human activities can be used to produce a mood change. What is then apparent is that on each of these some measure of psychological dependence occurs assayed in terms of an unnatural drive towards that pleasure-seeking goal. This may just consist of the need for the cup of tea on waking up; the obsessional completion of The Times crossword; the cultivation of prize blooms or vegetables; the irrational drive to watch some form of sport on a regular basis. It extends in well over 50 per cent of the populations of developed countries into the socially acceptable but true ‘addictions’ of smoking, drinking and gambling.

Peer and priest, senator and serf, doctor and dustman alike experience one or more excessive pleasure-seeking drives. We should consider each of these activities within a wider concept of ‘psychotropics’ and perhaps speak of those that are socially acceptable as the ‘social psychotropics’.

However, the concept of social acceptability immediately raises a value judgement. Within the group of the psychotropics such a judgement is difficult for there are no scientifically definable borders or limits between the various grades of dependence that exist-rather we should view the whole range of psychotropics as a spectrum (). At one end of the scale are the commonplace enjoyments of all of us to which no one can object, at the other the socially unacceptable patterns of those dependent, for example, on heroin. But how do we assign a rating order for the intermediate dependences? We cannot do so scientifically but are biased by the social fashions of our culture, nation and age and by our own pre-delictions and aversions. But even if we can establish a rating order, how can we define the border between acceptability and non-acceptability without value judgements subject to bias?

Just as normal levels of anxiety can be an important drive for the examinee or athlete and morbid anxiety can destroy the ability, so can nearly all these pleasure-seeking drives stimulate work for good or evil. The social object should be to encourage that for good and attempt to remove the component that brings evil. Education () will help this but legislation rarely does so and should be reserved for those activities where the dangers to society as a whole are greatest.

Thus the problem of dependence on drugs, the topic that is of prime interest to us, must be viewed not in isolation but as part of the wide realm of a full spectrum of’psychotropics’ many of which can be ‘overused’ or indeed ‘abused’ and which can give rise to dependence.