Genetics+and+Biological+Basis


 * Genetics and Biological Basis **

Numerous (animal and human) studies have revealed that there are certain receptors in the brain that may predispose individuals to alcoholism. D2dopamine receptors and dopamine may play an important role in alcoholism and other addictions, in brageneral (Kuehn, 2006). It has been found that individuals who have a current addiction to alcohol also have low levels of D2dopamine receptors.
 * Therefore, these low levels of have the potential of increasing susceptibility to alcoholism (and other addictions), and may conversely serve as a protective factor for individuals who have high levels of the receptor. Alcoholism has a strong genetic factor, accounting for up to 60% of the risk of developing the disorder (Kuehn, 2006).

A study reported by Kuehn (2006), looked at brain images extracted via positron emission tomography of individuals who had 3 first or second-degree relatives with alcoholism, (but no personal history of drug abuse or dependence. The results of the study showed that these individuals had higher levels of D2 dopamine receptors compared with the controls (those individuals who had no personal or family history of drug abuse or dependence).



The image on the right shows a comparison of two brains. New research has revealed that individuals who have a family history of alcoholism but do not develop the disorder (family-positive) themselves have higher levels of dopamine D2 receptors available than do normal (family-negative) controls. This finding suggests these receptors may have a protective effect (Kuehn, 2006).

**Neurochemical Precursors**

The genetic and biological basis of alcoholism and the potential of developing an Alcohol Use Disorder can be traced to various neurochemicals in many areas of the brain. Ratsma, Van Der Stelt, Gunning (2002), gave a comprehensive overview of the main 'players' that promote or enhance the likelihood of developing an addiction to alcoholism. The following are a list of neurotransmitters that were said to be affected in Children of Alchoholics (COA), versus a group of control participants, (parents did not have any history of AUDs):

1. Increased expression of GABAA receptors in frontal cortex

2. Decreased binding 5-HT transporter (SPECT)

3. Decreased number of noradrenergic neurons in locus ceruleus, as well as decreased levels of noradrenaline in plasma

**Endogenous Opiod Systems**

It has been proposed that alcohol may stimulate the release of certain opiod peptides, which in turn, could interact with the centres of the brain associated with reward and positive reinforcement and lead to further alcohol consumption (Gianoulakis, 2001). Ethanol stimulates the release of opiod peptides which then stimulates the release of dopamine, leading to alcohol reinforcement (Gianoulakis, 2001). Furthermore, Gianoulakis (2001) states, in family studies examining variations in genetics, it was found that individuals with a family history of alcoholism presented lower concentrations of plasma β-endorphin in the pituitary region.