People’s vulnerability to substance use varies as a result of the biological make up (Absi, 2007). Most people have virtually unrestricted access to drugs and related substances. However, not everyone gets to use drugs, and even those who experiment with the substances do not all get addicted. Moreover, the possibility of developing habitual use of substances is not the same across the divide. Naturally, drug abuse starts in adolescence, reaches a peak during the twenties and rapidly drops in the later years. Still, this trend is not universal as some individuals persist with the habit much later into adulthood. These disparaging variations among personalities are attributable to inherent genetic conditions and physical traits (Absi, 2007). Therefore, there is enough evidence ruling out dependence on substance as a socially acquired disorder.

Vulnerability and Genetics

The process of substance abuse and the eventual addiction are a complex one. It is a process that derives heavy influence from the behavioral tendencies of the individual as well as genetic structure thus contributing to the apparent differences among various users. The biological influences upon substance dependence operate at various levels. The biological factors that drive a person to pick up drug abuse appear to vary from those influences that lead the user into deeper use and heavier dependence.

It is also crucial to note that vulnerability can be varied by factors known to stimulate the desire to stop the abuse habit (Preeti, 2007). These biological factors are also responsible for shielding the individual from developing a regular abuse pattern that eventually solidifies into dependence. The genetic variants are prone to catalyzing modified substance reinforcing properties and altering the drug’s pharmacological effect. They also trigger the desire to seek sensation that a certain drug offers which influences the individual to develop a routine for using the substance. The level or amount of the gene in a person determines how these features come into play during the process leading to addiction (Alper and Bastiaans, 1999).

The said gene is also a determinant in a user’s choice of substance. Research into the addiction inducing genetic component follows an interlink age between neurological aspects of vulnerability and substance use, habit maintenance and the uncontrollable resistance to stopping the use (Comer et al, 2007). The studies focus on individuals fitting into a certain category of use duration and dependence extent in an attempt to demystify the genetic make up associated with drug use vulnerability. The studies involved subjects related by the family, so as to establish the precise influence of biological vulnerability on substance dependence. The resultant findings demonstrate that there exists evidence on the genial contribution to disorders such as addiction (Elmer et al, 2000). There is indeed a genetic pattern of vulnerability to chronic substance dependence.

The Endorphin-Deficiency Theory

This theory seeks to explain how an addict’s inherited genealogy is responsible for his addictive susceptibility. The levels of susceptibility to addiction vary from individual to individual due to the inherent mechanisms within (Preeti, 2007). Narcotic addiction is a metabolic disease and the addictive tendency usually outlives the dependence on a drug (Absi, 2007). This metabolic disorder can either precede or follow the narcotic use. This implies that the perennial consumption of narcotics not only leads to a constant and chronic demand for the substance, but an addict could already have had such a demand at the time he began using the drug and became dependent on it.

These findings later supported new knowledge that the body is capable of producing its opiates known as endorphin (Elmer et al, 2000). The addict could possess an inbred endorphin disorder that makes them very sensitive to pain. Consequently, such a person is open to any narcotics that present an opportunity of alleviating their pain. In fact, some theorists argue that the affected individuals not only desire, but could require such relief. This deficiency in endorphin is an indication of a continuous and irreversible dependence on substance that takes place in unusual scenarios of addiction. The individuals in possession of the metabolic deficiency, comprise of only a small proportion of lifetime addicts.

Global Biological Addiction Theories

There exists an addictive illness to which can be attributed why a large number of addicts have previous histories of addiction to different substances (Smith& Meyers, 2007). This explains why it is so difficult to understand predetermined responses could lead the same individual to be as indulged in substances as unrelated as alcohol, Valium and Cocaine. These substances could as well be interlinked by similar activation mechanisms as well as by their pharmacological affluent effects (O’Donohue & Fergusson, 2006).

Still, some scientists pursue the line of thinking that indeed, biological defects are responsible for multiple drug use. According to Lowinson& Ruiz (2005), substances like cocaine, amphetamine and opiates are capable of rousing brain points known to be reward centers. There is also credible proof that some people possess an elevated inclination to substance abuse and as a result, abuse a diverse range of dissimilar substances. The possibility of genetic and environmental attributes feeding into the reward centers to produce unstable and imbalanced reactions is solid ground for investigating the biological backgrounds of drug dependency.

Smith& Meyers (2004) presents a neurological model explaining addiction as a result of self-induced variations in neurotransmission. A certain gene is responsible for producing enzymes that affect hormones, as well as neurotransmitters, and the individual ends up developing a personality more prone to substance abuse.

Interpersonal Addiction

The dependence on drugs could also be explained by the net effect of interpersonal, physical relationships. Chemical imbalances drive substance abusers to engage in self-destructive, compulsive and unhealthy relations with others in similar circumstances. These people are no different from the rest of the populace.

However, they have a biological inclination to fall in love unconditionally and uncontrollably and consequently indulging in disastrous romantic associations (Gass& Olive, 2008). Dutcher& Moore (2007) suggests that subdued neurochemical regulation leads the affected persons to become excessively romantically attached, mostly to inappropriate partners, and end up overtly depressed following the failure of these relationships.

In conclusion, though the biological theories do not exhaustively provide concrete evidence that substance use is exclusively a manifestation of biological and genetic traits inherent in the abuser; they give ample ground for further investigation. On the other hand, dependence on drugs cannot be dismissed as a socially acquired disorder since it is evident that an individual’s biological extraction and genetic deficiencies trigger the vulnerability.








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Elmer, G. I, Uhl, G.R, Labuda, M.C& Pickens, R.W. (2000). Human Substance Abuse Vulnerability and Genetic Influences. National Institute of Drug Abuse 23(1).

Dutcher, L.W& Moore (2009). Neurobiotic Reinforcement on Substance Dependence. Journal of Behavior Analysis of Sports, Health Fitness and Behavioral Medicine, 2(1).

Gass, J.T, &Olive, M.F (2008). Glutamatergic substrates of drug addiction and alcoholism. Biochem. Pharmacol.75(1).

Lowinson, J.H& Ruiz, J.H (2005). Substance Abuse: A Comprehensive Textbook(4th Ed.). Philadelphia: Lippincott Williams & Wilkins.

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Smith, J.E& Meyers, R.E (2004). Behavioral Approaches to Treating Substance Abuse-Abusing Individuals. The Behavior Analyst Today 5(4).

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