A drug addict pays the ultimate price for a days fishing'

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Drug Addict Uses Own Face As Fishing Bait
from the old practise of using bacon rind for
fishing bait. Within 10 minutes of his first cast
he hauled up a 1lb whiting, several others
followed including a 7lb cod. It was amazing
nobody else was catching anything yet he was
pulling them out like there was no tomorrow".
Sadly for the unnamed angler there was no
tomorrow as he passed out and died though loss of
blood. Blyth has long suffered from its drug
problem and the council is worried that copycat
drug addicts will follow. The use of human flesh
has since been banned from local fishing
competitions for legal reasons.
A drug addict pays the ultimate price for a days
fishing.
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Percentage of UK population who smoke
Source Office of national statistics
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Percentage of UK adult population drinking more
than the recommended daily number of units of
alcohol.
RDA male 3-4 units per day RDA female 2-3
units per day
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• Why do people take drugs?
• (Bardo et al, 1996 )
• Exposure theories - all humans are at risk of
  becoming addicted to drugs given sufficient
  exposure, because drugs interact with and change
  the brain in such a way as to create continued
  motivation to use the drug.
• Where these theories differ is in their
  explanation what sort of changes drugs produce in
  the brain, and what sort of motivation drugs give
  rise to that drives subsequent drug use.
• Adaptive theories claim that only certain
  individuals are at risk of becoming addicted
  because they have a particular vulnerability
  (addictive personality) that allows drugs to
  generate addiction behaviour more readily.
• We will cover individual differences in
  vulnerability in lecture 2.

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Exposure theories of addiction

• Most theories of addiction are exposure theories
  in that they assume that addiction is an
  inevitable consequence of drug exposure.
• As these theories have developed over the last
  40 years, they have changed our view of how drugs
  give rise to motivation to take the drug at a
  future point in time.

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• Withdrawal (Wikler 1965)

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• Withdrawal (Wikler 1965)

Physically agonising withdrawal is a significant
barrier to quitting/abstinence. Addicts continue
to use the drug in order to avoid
withdrawal. Negative reinforcement (the drug acts
like a painkillers). But what about the initial
rush or high - positive reinforcement? The
initial high exhausts the reward/pleasure centres
in the brain, and so once the drug wears off, you
go into withdrawal. The experience of aversive
withdrawal is more motivating to take the drug
than is the pleasurable experience of the high.
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• Withdrawal (Wikler 1965)
• Criticism

• A key criticism of withdrawal theory, was that
  medical supervision of withdrawal was not as
  successful as it should have been at engendering
  long term abstinence.
• Drug users would often relapse despite having
  undergone supervised withdrawal from drugs.
• To explain this, Wikler proposed that withdrawal
  could become conditioned to external cues, such
  that exposure to these cues could elicit
  withdrawal at any time, and thereby precipitate
  relapse.

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• Pavlovian conditioning (Pavlov 1927)

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Pavlovian conditioning (Pavlov 1927)
Bell
Food

Reflex Stimulus-response Habit
Modified through learning
Hardwired
Saliva
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Reflex

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• Conditioned Withdrawal (Wikler 1965)

Recall, that Wiklers problem was that drug users
would often relapse despite having undergone
supervised withdrawal from drugs. Wikler
proposed that external stimuli (such as the
addicts bedroom, living room) which were
consistently paired with withdrawal, came through
the process of Pavlovian conditioning, to be able
to elicit withdrawal themselves. Such
conditioned withdrawal could explain relapse
following medically supervised withdrawal from
the drug.
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• Conditioned Withdrawal (Obrian 1977)

volunteers on methadone maintenance were given a
low dose of naloxone to precipitate opiate
withdrawal symptoms (reduced skin temperature due
to vasoconstriction - goose flesh) while
simultaneously presented with a peppermint odor
in a conditioning chamber. There is no effect
during the pre-training session (trials 2 and 3),
but the naloxone during the training trials
produces a sharp drop in skin temperature. During
the test trial with no naloxone, the conditioning
stimulus (peppermint odor) alone produces a
temperature drop similar to the unconditioned
response.
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• Conditioned Withdrawal (Wikler 1965)
• Criticism

Anecdotal reports from drug addicts who had
relapsed suggested that what caused them to
relapse was the immediate possibility to purchase
the drug (i.e. bumped into dealer), or the
proximity of contexts in which drug use had
previously taken place (i.e. hanging out at the
shooting gallery with old mates), not, as
predicted, by contexts in which withdrawal had
occurred most frequently (i.e. bedroom).
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• Opponent process theory and tolerance
• Solomon and Corbit 1973, Siegel 1983)

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Tolerance and overdose Study by Siegel et al
(1982) High heroin dose given to heroin
tolerant rats Environment Deaths
() Novel 96 Usual 64 Demonstrates that
environmental cues associated with drug taking
(not the later withdrawal effect) come to elicit
a drug opposite response (escalating dose). This
drug opposite response may be aversive, and
motivate drug taking to alleviate this state
(negative reinforcement).
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Positive reinforcement self-administration
One problem for negative reinforcement theories
(the idea that drugs are taken to avoid the
aversive states produced by drugs) is that
animals and humans rapidly learn to obtain drugs,
in exactly the same way that they learn to obtain
natural rewards such as food, water and access to
a sexual partner.
This suggests that drugs are taken in order to
achieve the pleasurable high they produce. i.e.
drugs are positive reinforcers.
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Positive reinforcement drug cues
Another problem for negative reinforcement theory
is that drug cues motivate drug consumption and
are rated as pleasant, rather than
aversive. These data are consistent with the idea
that drug cues prime drug taking by reminding the
addict of the positive appetitive qualities of
the drug (not by eliciting an aversive state).
Hogarth et al, unpublished data
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Positive reinforcement dopamine and the
hijacking of natural reward
Midbrain dopamine cells increase activity when
humans or animals detect or consume both natural
rewards (food, water, sex) and drugs of abuse
(nicotine, cocaine, heroin). Suggests that drugs
of abuse hijack the brain substrate for
reward/pleasure, and are consumed because drug
taking is positively reinforcing.
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Conclusion and summary

• Drug taking is motivated by a complex set of
  mechanisms, which are thought to change as the
  drug user progresses from being casual to
  addicted.
• Initially, drug taking is motivated by an
  expectation of the positive or pleasurable
  consequences of the drug.
• Environments that are associated with the drug
  pleasure acquire the capacity to prime drug
  taking, by activating a memory of the pleasurable
  drug effects.
• With further drug use, conditioned tolerance
  develops (that is, cues associated with the drug
  come to activate a drug opposite counter
  reaction) which causes an escalation of dose to
  achieve the same effect.
• In addition, the conditioned counter reaction
  motivates drug taking to alleviate this aversive
  state.
• After sufficient exposure to the drug, when the
  drug is stopped, the aversive withdrawal state
  that follows provides a significant barrier to
  remaining abstinent because drug taking can
  quickly alleviate this aversive state.
• Finally, cues that are associated with the
  experience of repeated withdrawal come to elicit
  a conditioned aversive withdrawal state, which
  again motivates drug taking to alleviate this
  state.