What causes addiction, and why is it so hard to treat? - Judy Grisel
As of 2021, more than 36 million
people worldwide
were estimated to be experiencing
substance abuse disorder.
This condition spans a spectrum
of patterned drug use
that causes issues in a person’s life.
At the more severe end of the spectrum
is substance addiction.
To understand why some people are
more susceptible to addiction
and why it can be so difficult to treat,
let’s take a look at how addictive drugs
affect the body.
When someone repeatedly uses
an addictive substance,
their brain may adjust to account
for its regular presence.
This is called tolerance;
it diminishes the drug’s effect
and means more is required
to produce the same experience.
Alcohol, for instance, increases the
transmission of chemical messengers
like endorphin and GABA,
which promote sensations
of pleasure and calmness.
When someone uses alcohol frequently,
their brain will adapt to its presence.
So when they don’t use it,
their brain receives fewer signals
from those pleasure- and
calm-inducing neurotransmitters,
which impacts their energy and mood.
In addition to the unique effects
each addictive substance has,
all of them alter the release of dopamine
in a brain region called
the nucleus accumbens.
This area is part of the brain’s
reward pathway,
which is sensitive to experiences
that give us pleasure
and drives us to repeatedly seek them out.
The reward pathway is essential
to our well-being—
but addictive substances also exploit it.
When someone is repeatedly
using a substance
and their body has adapted
to its presence,
they may develop dependence
where the drug is necessary
for them to function comfortably.
Meanwhile, repeated use can decrease
the influence of the brain’s cortex,
which is responsible for driving
deliberate decision-making
and limiting impulsive behaviors.
And it can increase the influence
of the brain’s subcortex,
which is crucial in habit-learning
and impulsivity.
Together, these changes can make
someone feel a lack of control
over how they’re using a substance.
This can mean suffering
in other facets of their life
and taking risks to continue using it.
If the substance leaves their system,
their body's equilibrium is disrupted,
so they may experience cravings
that motivate thoughts and behaviors
of seeking and using the drug.
And if they continue without
the substance,
they may experience withdrawal.
Opioids, for example,
relieve pain and induce sedation.
Withdrawal from them causes
heightened pain, anxiety, and insomnia.
The faster a drug reaches the brain
and stimulates the reward pathway,
the more addictive it is.
For example,
heroin and morphine have similar effects,
but heroin’s chemical structure
enhances its ability
to penetrate the blood-brain barrier
and bind to specific receptors.
This makes it faster acting
and more addictive than morphine.
Meanwhile, compared to nicotine patches
and gum,
regular and electronic cigarettes
are more addictive
because smoking and vaping
deliver nicotine to the brain fastest.
Depending on their chemical structure
and mode of delivery,
drugs vary in how addictive they are—
but people also vary in how susceptible
they are to substance use disorder.
Scientists think this is due to a mix
of life experiences
and genetically inherited traits,
though neither predetermines addiction.
Trauma and mental health conditions appear
to make people more susceptible.
And, overall, using addictive substances
before 18
is considered a strong risk factor.
This is in part because the reward
pathways of younger brains
are especially sensitive.
Many of the genetic factors at play
remain unknown,
but some genes do seem to track
with certain substance use disorders.
For example, specific genes increase
the risk for nicotine addiction
by making certain receptors
more sensitive to nicotine
and withdrawal from it more difficult.
At the same time,
some genes actually make people
more resistant to substance use disorders,
such as genes that slow
the breakdown of alcohol,
leading to unpleasant side effects that
make people less interested in drinking.
In fact, one drug that treats
alcohol use disorder
operates with this very mechanism.
Detoxing from a substance the body
has become dependent on
can be extremely difficult.
And in some cases, abruptly quitting
can also be physically risky,
so it isn’t always advised.
Beyond detoxing, quitting is
often a long-term process.
It’s aided by treatment plans
that prioritize
addressing underlying conditions;
developing new associations
with experiences
previously linked with drug use;
and creating safe,
supportive environments.
Ultimately, both addiction and recovery
are the results of a brain
with an incredible ability to adapt
from experience.
