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Drugs & Consciousness
Fig. 10.1 Neuroadaptation is not the same as drug tolerance; in
the former, brain chemistry is adapting to offset the drug, while
in the latter, more drug is needed with each repeated exposure.
Addiction must be compulsive, with adverse physiological
consequences; removal of the substance will result in
withdrawal.
Consider the opposite: Attributing serial adultery to a 'sex
addiction' does not explain the sexual impulsiveness. (Radford,
2010).
The checklist for substance dependence Table 10.1
(mp116,c3.4p114) will be on the next exam.
As blood alcohol levels rise, moral judgments falter. (McDonald
et al., 1995 mp117, cp115).
Binge drinking impairs the growth of synaptic connections,
especially the ones that create memories. (Crews et al., 2007 m
p118, cp115)
Drugs & Biology
Alcohol is a morphoid agonist, with the added feature that the
compound does not get created prior to crossing the bloodbrain barrier.
It is a sedative that slows neural processing.
Alcohol disrupts memory formation at the synapses, in the
hippocampus, which is the most sensitive and easily damaged
part of our brain (and the newest in terms of evolution).
Alcohol suppresses REM sleep, leading to 'blackouts'.
Fig 10.2 (mp118,cp116) Alcohol dependence shrinks the brain.
Alcohol produces 'myopia'; it focuses attention on an arousing
situation, and distracts attention from normal inhibitions.
(Giancola, 2010, mp118, cp116).
Opiates are endorphin agonists, causing withdrawal. Review:
what is an agonist?
Drugs & Biology
Adopted individuals are more susceptible to alcohol
dependence if a biological parent has a history of alcohol
abuse.
Having an identical twin (rather than a fraternal twin)
increases risk of alcohol dependence. (Kendler et al. 2002
mp126, cp124).
Researchers have identified genes common among
people predisoposed to alcohol dependence, and are
seeking genes for tobacco addiction (Numberger & Bierut,
2007 mp126, cp124).
These genes appear to produce deficiencies in the
dopamine reward system.
While triggering temporary dopamine-produced pleasure,
these drugs disrupt the normal dopamine balance.
Make note of this for Web Article 3: PKM-Zeta may be one
of these anti-addiction drugs.
Drugs & Biology
Fig. 10.4(mp120,c3.24p118) Nicotine reaches the brain in 7
seconds, twice as fast as intravenous herion.
Nicotine releases a flood of neurotransmitters: epinephrine and
norepinephrine diminish appetite and boost alertness and
mental efficiency; dopamine and opioids calm anxiety and
reduce sensitivity to pain.
Cocaine: see Fig. 10.5 (mp122,c3.25p119): By binding to a site
that normally reabsorbs neurotransmitter molecules, cocaine
blocks the reuptake of dopamine, norepinephrine, and
serotonin.
The extra neurotransmitter molecules remain in the synapse,
intensifying their normal mood altering effects and producing a
euphoric rush.
When the cocaine level drops, the absence of these
neurotransmitters produces a crash.