Question

Describe the neurobiology of chemical addiction

Answer 1

Neurobiology of Chemical addiction:

Addiction is a state that is characterised by compulsive drug use or compulsive engagement in rewarding behaviour , despite negative consequences.    Neurobiology is the scientific study of nerve and brain function in people and animals. Neurobiology of Chemical addiction studies the anatomical and physiological changes in a person who have an addictive nature to chemicals or substances such as Nicotine, alcohol, Cocaine, Morphine etc.

Nervous system is an organ system that coordinates activities of muscles, monitor organs , constructs and processes data received from the senses and initi actions. This system consists of brain , neurons or nerve cells, spinal cord and nerves. Chemical addiction or substance dependence affects the whole nervous system, so the Health professionals should have a basic understanding about the Neurobiology of Addiction.  

When a person continously uses alcohol or other drugs, it may cause changes in his brain. A neurotransmitter called Dopamine activity is altered by the repeated usage of such chemicals. Basal ganglia is the region in the brain that controls the feelings of rewarding and make is to learn such behaviour. Addictive chemicals produces sudden rush or increase in Dopamine level at the area of Basal ganglia, that produces a euphoric effect in brain. With the repeated usage of the drugs , Dopamine sensitivity become less to the chemical as the system gets adapted to it. Individual have to take higher amount of the drug to get the same Dopamine rush or the Euphoria effect or the ' high state' . This condition is called 'tolerance ' to drug .

Drug dependence is the irresistible physical or psychological need especially for a chemical substance. Drug tolerance gradually leads to Drug dependence. Other cues in the environment, like friends , places to drink, or objects or glasses for consuming it are associated with reward feeling in the brain. So whenever an addicted person see or come in contact with such environment or friends, he may get the remainders in brain for the same ' high'.

Extended Amygdala and prefrontal cortex has   a major role in dependence and withdrawal. Extended Amygdala reacts in response to neurotransmitters burst during the rewards. It stimulates the brain to avoid unpleasant situations. Also amygdala controls the pleasure seeking behaviour and avoidance of pain . Repeated usage of drugs makes changes in these activities of the brain. Patient may develop withdrawal symptoms or too much distress , once he get addicted to it . Any of a group symptoms associated with a discontinuance of a drug, by a person who has become addicted to it. He may get relief only from the Dopamine surge due to the substance that he abused. Other things he used to enjoy before may not give tha same pleasurable effects, once he develop an addiction to chemicals.  

There are ' Decision making circuits ' or ' judgement circuits' in the prefrontal cortex. This area of brain involved in executive function. A healthy individual can overcome the changes caused due to alteration in the brain and neurotransmitters as a result of substance abuse, through these circuits of Decision making/ judgement. But in severe substance use disorder, thses circuits may get alterd or destroyed, resulting in compromised self control.

Some people may take the substance to relieve the stress an anxiety or depression. They may feel false relief from these stress and anxiety after taking the substance. This relief (false) can negatively reinforce the person . This negative reinforcement makes the person to repeat the behaviour, again when he is getting stress.