Explanation for nicotine addiction: brain neurochemistry

Question 1

neurochemistry definition

Answer 1

relating chemicals in the brain that regulate biological and psychological functioning

Question 2

dopamine definition

Answer 2

neurotransmitter generally has excitatory effect and is associated with the sensation of pleasure. unusually high levels are associated with schizophrenia and unusually low levels are associated with parkinson’s disease

Question 3

what did Dani and Heinemann focus on

Answer 3

dopamine in their desensitisation hypothesis if nicotine addiction. This begins with neurotransmitter acetylcholine

Question 4

what does ACh stand for

Answer 4

acetylcholine

Question 5

what does acetylcholine do

Answer 5

-plays a key role in all nervous system activity, which means there are ACh receptors in surfaces if many neurons in the central nervous system

Question 6

what is nicotinic acetylcholine receptor (nAChR)

Answer 6

type if ACh which is activated by ACh or nicotine

Question 7

what happens when nicotinic acetylcholine receptor (nAChR) are activated

Answer 7

neuron transmits dopamine. this is immediately followed by shutdown within milliseconds the nAChrs temporarily cannot respond to neurotransmitters

Question 8

when are nicotinic acetylcholine receptor (nAChR) said to be desensitised

Answer 8

when the have shut down due to nicotinic acetylcholine receptor (nAChR) being activated by nicotine, transmitting dopamine

Question 9

what leads to downregulation

Answer 9

desensitisation

Question 10

what is downregulation

Answer 10

reduction in the number if active neurons because fewer of them are available

Question 11

what are nicotinic acetylcholine receptor (nAChR) concentrated

Answer 11

in the ventral tegmental area

Question 12

how is a pleasurable effect created when nicotine is present (mesolimbic pathway)

Answer 12

-when nicotinic acetylcholine receptor (nAChR) are stimulated by nicotine, dopamine is transmitted along the mesolimbic pathway into the nucleus accumbens
-this triggers the release if more dopamine form the nucleus accumbens into the frontal cortex

Question 13

how is a pleasurable effect created when nicotine is present (mesocortical pathway)

Answer 13

-same time as the mesolimbic pathway
-dopamine is transported along the mesocortical pathway to be released directly in the frontal cortex

Question 14

how is a pleasurable effect created when nicotine is present

Answer 14

-the mesolimbic and mesocortical pathways are part of brains dopamine reward system
-nicotine powerfully activates this system and results in pleasurable effects (such as mild euphoria, increased alertness and reduction of anxiety)
-these effects became associated with smoking through operant conditioning

Question 15

what causes withdrawal

Answer 15

-as long as the person is smoking, the nicotinic acetylcholine receptor (nAChR) are continually desensitised
-when the person does not smoke for a long period of time, such as at night, the nicotine disappears from their body
-this cases the nicotinic acetylcholine receptor (nAChR) to become functional again, so dopamine neurons resensitise and become more readily available (upregulation)

Question 16

why does someone with smoking addiction have withdrawal symptoms

Answer 16

form the lack of nicotine

Question 17

what is the experience of withdrawal in terms of nicotinic acetylcholine receptor (nAChR)

Answer 17

-nicotinic acetylcholine receptor (nAChR) become overstimulated by ACh (as there is no nicotine to bind to them)
-nicotinic acetylcholine receptor (nAChR) are most sensitive at this point
-this is why most smokers describe the first cigarette if the day the day the most enjoyable –> reactivates dopamine reward system

Question 18

how is withdrawal avoided by smokers

Answer 18

having another cigarette

Question 19

what does avoiding withdrawal create

Answer 19

constant cycle of daytime downregulation and night time upregulation, creating long-term desensitisation of nicotinic acetylcholine receptor (nAChR)

Question 20

what does continues exposure of nicotinic acetylcholine receptor (nAChR) to nicotine cause

Answer 20

permeant changes to brain neurochemistry as there is a decrease is number of active receptors

Question 21

how is tolerance to nicotine developed

Answer 21

smoker has to smoke more to get same effects

Question 22

strength of brian chemistry as an explanation of nicotine addiction - research support

Answer 22

-support from human research
-research has provided indirect support for the role of dopamine. McEvoy et al studied smoking behaviour in people with schizophrenia who were taking antipsychotic drugs Haloperidol. this drug is a dopamine antagonist. these people has a significant increase in smoking, presumably as a form of self-medication as individuals used nicotine as a means of increasing depleted dopamine levels –> supports view dopamine has a key role in neurochemistry of nicotine addiction

Question 23

limitation of brian chemistry as an explanation of nicotine addiction - counterpoint to research support

Answer 23

-explanations that only consider the role of dopamine are limited
-dopamine system is central but research shows increasing complex interaction of several neurochemical systems. Watkins et al include neurotransmitter pathways and other systems such as endogenous opioids –> neurochemistry of nicotine addiction cannot be fully understood if looking only at dopamine

Question 24

strength of brian chemistry as an explanation of nicotine addiction -real world application

Answer 24

-neurochemistry leads to new treatments
-Nicotine replacement therapy (NRT) helps smokers quit. this has been developed as nicotine has been identified as the addictive component in cigarettes with effects on nAChRs. NRT products such as patches and gum deliver a controlled dose of nicotine. This acts neurochemically by binding with nAChRs and mimicking effects of nicotine in cigarettes including the dopamine release. cravings are satisfied and reduces withdrawal symptoms by gradually reducing dose of nicotine over weeks –> greater understanding of neurochemistry led to an effective treatment if nicotine addiction

Question 25

limitation of brian chemistry as an explanation of nicotine addiction - withdrawal symptoms

Answer 25

-does not fully explain withdrawal
-according to theory, withdrawal symptoms depend mainly on the amount of nicotine in the body. Gilbert suggests these factors are not strongly correlated and argues instead that withdrawal depends more on the environment and personality. for example, those scoring highly on personality dimension of neuroticism generally experience worse withdrawal symptoms than people who are emotionally stable –> withdrawal effects can be explained in other ways without reference to amounts of nicotine

Question 26

evaluation of of brian chemistry as an explanation of nicotine addiction -determinism

Answer 26

-neurochemical explanation is biologically determinist, suggesting we become addicted to nicotine because of chemical events in the brain involving dopamine reward that are beyond our control, including withdrawal. so nicotine addiction is inevitable in someone who starts smoking
-however, nicotine addiction mat not be inevitable. some people smoke without becoming dependent and show no withdrawal symptoms when the stop (Shiffman and Paty 2006). some smokers find it easier to stop than others due to their personality, such as Gilbert’s research on neuroticism