Drug Abuse: Causes

DRUG ABUSE

The Causes of Drug Abuse

Investigations show that some alcoholics begin to drink due to social pressures or in response to stressing situations in their lives. Since the drinking behavior is initiated, its fixation is conditioned by the alcohol-induced psychophysiological reward. Contrariwise other alcoholics seem to be driven to use and abuse alcoholic beverages by an internal compulsion.

Types of Alcoholism

Type I	Occurs both in men and women; requires both genetic and environmental influences; begins fairly late in life; greater possibility of recovery.
Type 2	Occurs primarily in men; overwhelmingly genetic in origin; begins during adolescence or early adulthood; usually associated with criminal behavior; lesser possibility of recovering.

Cloninger, Sigvardson & Bohman – in Alcohol Health and Research World – vol. 20, nr. 1, 1996

It seems that the same happens in relation to other psychoactive substances.

Genetic and inborn factors as well as learned and acquired factors for the drug abuse can thus be identified.

The influence of genetic factors on alcoholism was already anticipated in ancient times. Plutarch stated that "drunkards beget drunkards". In his book "Alcohol and the addictive brain", Kenneth Blum summarizes the results of decades of studies about genetics vs. alcoholism stressing that:

Monozygotics twins of alcoholics are at significantly higher risk of developing alcoholism than dizygotic twins.
Children of alcoholics are approximately four times as likely to become alcoholics as children of non-alcoholics, even when the children of alcoholics are separeted from their biological parents at birth, and reared by non-alcoholic adoptive parents.
Children of non-alchoholic parents have a low rate of alcoholism, even when adopted by alcoholic parents.
There is a 25-50% lifetime risk of alcoholism among sons and brothers of severely alchoholic men. Alcoholics and their offspring show several neurobiochemical abnormalities, such as:

Increased resistance to the depressor effects of alcohol.
A smaller EEG alpha frequency response to alchool ingestion.
Lower mean cerebrospinal fluid levels of 5HIAA ( 5-hydroxy-indolacetic acid) the major metabolite of serotonin.
Enhanced sensitivity of the pituitary b -endorphin system to alcohol intake.
Behavior patterns similar to those observed in people with mild dysfunction of the frontal lobes (impulsiveness, attention deficits, hyperactivity, and poor emotional regulation).

In a paper that appared in a 1996 issue of American Scientist, Blum et al advance, as the physiological basis for drug abuse, what they call reward deficiency syndrome.

The Brain’s Drug Reward Systems

The cocaine and amphetamine reward system includes neurons using dopamine found in the ventral tegmental area, connected to the nucleus accumbens and other areas such as the prefrontal cortex.

The opiate reward system besides the aforementioned structures, includes also areas that use endogenous opioids as neurotransmitters like the arcuate nucleus, amygdala, locus ceruleus, and the periaqueductal gray area.

The alcohol reward system, besides the dopaminergic neurons of the ventral tegmental area and the nucleus accumbens, includes also structures that use GABA (gamma-aminobutyric acid) as a neurotransmitter, like the cortex, cerebellum, hippocampus, superior and inferior colliculi, amygdala, and nucleus accumbens.

The brain’s drug reward system – NIDA Notes – vol. 11, nr. 4, September/October, 1996

Brain & Mind Magazine 3(8), Jan/March 1999
An Initiative by the Center for Biomedical Informatics
Copyright (c) 1998 Universidade Estadual de Campinas, Brasil
Published on 18/Jan/1998