Addiction is a disorder characterized by compulsive engagement in rewarding stimuli despite adverse consequences. It arises from changes in the brain's reward system due to repeated exposure to addictive substances. The brain disease model of addiction posits that addiction develops over time through transcriptional and epigenetic mechanisms in the brain's reward system in response to chronically high levels of an addictive stimulus. The nervous system is affected in the brain stem, limbic system, and cerebral cortex, which control basic functions, emotions/happiness, and thinking/decision-making respectively. Mind-altering drugs impact levels of neurotransmitters like dopamine, serotonin, GABA, and norepinephrine, which regulate functions like pleasure, mood, anxiety, and focus

1. Peer graded assignment-Coursera
Understanding the brain-The Neurobiology of everyday life
ADDICTION
The brain is the most complex organ in our bodies.It regulates
your body's basic functions, enables you to interpret and
respond to everything you experience, and shapes your
behavior.
Addiction is a biopsychosocial disorder characterized by
compulsive engagement in rewarding stimuli despite adverse
consequences. Despite the involvement of a number of
psychosocial factors, a biological process—one that is induced
by repeated exposure to an addictive stimulus—is the core
pathology that drives the development and maintenance of an
addiction, according to the "brain disease model" of
addiction.The brain disease model posits that addiction is a
disorder of the brain's reward system which arises through
transcriptional and epigenetic mechanisms and develops over
time from chronically high levels of exposure to an addictive
stimulus (e.g., eating food, the use of cocaine, engagement in

2. sexual activity, participation in high-thrill cultural activities
such as gambling, etc.).
The nervous system is affected through the brain stem,
limbic system, and cerebral cortex.
The brain stem controls life-sustaining functions, including
sleeping, breathing, and heart rate.
The limbic system holds the brain’s reward circuitry and helps
to control emotions and the ability to feel happiness.
The cerebral cortex is considered the “thinking center” of the
brain, managing problem-solving, planning, and decision-making
abilities as well as helping people to process information
provided by their senses.
Mind-altering drugs may slow down or speed up the central
nervous system and autonomic functions necessary for living,
such as blood pressure, respiration, heart rate, and body
temperature. Levels of some of the brain’s chemical
messengers, or neurotransmitters, are also impacted by drug
abuse, including:
-Dopamine: this neurotransmitter regulates moods, enhances
pleasure, and is involved with movement, reward and
reinforcing behaviors, motivation, and attention.

3. -Serotonin: this neurotransmitter is responsible for
stabilizing moods and regulating emotions.
-Gamma-aminobutyric acid (GABA): GABA acts as a natural
tranquilizer, mitigating the stress response and lowering
anxiety levels as well as slowing down functions of the central
nervous system.
-Norepinephrine: Similar to adrenaline, norepinephrine is
often called the “stress hormone,” as it speeds up the central
nervous system in response to the “fight-or-flight” response.
It also homes focus and attention while increasing energy
levels.
My brother,a student in college, has been suffering from
opioid addiction for almost a year now.This has completely
taken over his life almost irreversably sometimes.When I ask
him about it he simply tells me it is out of his control and that
even though he is well-aware of the danger this condition
implies there is nothing that could change it at this point.This
course has pointed out multiple possible issues that could have
either led to this or proceed with from this point on such as
memory loss , the parts in the nervous system affected
,perception, voluntary movements ,etc.It helped me unerstand
this beyond his words with actual biological information.

4. Sources- https://americanaddictioncenters.org/health-
complications-addiction/central-nervous-system
-https://en.wikipedia.org/wiki/Addiction#cite_note-
Cellular_basis-3