SUBSTANCE MISUSE AND DEPENDENCE

Question 1

substance misuse

Answer 1

defined in ICD-10 as a disorder of regulation of substance use arising from repeated or continuous use of that substance and consisting of a strong internal drive to use that substance

Question 2

dependence

Answer 2

physical need the body develops towards a particular substance

Question 3

addiction

Answer 3

the altered behaviour as a result of an overwhelming psychological need for a substance

Question 4

associated components with substance misuse

Answer 4

• behavioural aspects
• physical aspects
• psychological and associative aspects
• socioeconomic/environmental aspects

Question 5

behavioural pattern of drug use

Answer 5

1. overwhelming involvement with the use of a drug (compulsive use)
2. the securing of its supply (compulsive drug-seeking)
3. a high tendency to relapse after withdrawal

Question 6

theories of dependence - negative reinforcement model

Answer 6

physical dependence (withdrawal theory)
- relates mostly to opiates, barbiturates, alcohol
- based largely on increased tolerance and physical dependence

Question 7

theories of dependence - positive reinforcement models

Answer 7

positive incentive (reward) theory
- relates mostly to cocaine, amphetamine, nicotine
- based largely on reward and reinforcement

Question 8

theories on dependence - problems with the negative model

Answer 8

• amphetamine, cocaine, nicotine form strong dependency but have relatively little withdrawal effect
• alcohol and barbiturates have greater withdrawal but cause less dependence than heroin

Question 9

what is a critical incentive during addiction

Answer 9

speed of effect
- heroin is biochemically converted to morphine in the body
- heroin enters the brain faster than morphine

injection > inhalation > absorption

Question 10

cocaine speed into the bloodstream

Answer 10

IV > smoked > intranasal > oral

Question 11

key dependence/reward pathways in the brain that operate via dopamine transmission

Answer 11

1. dopamine signalling from the ventral tegmental area (VTA) to the nucleus accumbens (NA) is increased by drug action
2. glutamate projections from the NA cause the prefrontal cortex to remember the environments and behaviours which leads to the reward
3. excess signalling of glutamate neurons in the prefrontal cortex stimulates the NA, triggering drug-seeking behaviours at the expense of normal behaviours

Question 12

environment/cues and relapse

Answer 12

dopamine release and sensitization creates a form of memory that cues (drug paraphernalia, social situation etc.) can induce dopamine release… even in the absence of drug

this could be a driver of relapse

Question 13

how do different drugs of misuse act

Answer 13

1. stimulants (cocaine, nicotine)
2. depressants (tranquilisers, alcohol)
3. opioids (heroin, methadone)
4. marijuana/cannabis (clear dependence or reduced drive, memory problems etc.)

Question 14

actions of stimulants

Answer 14

• cocaine inhibits the dopamine reuptake transporter
• amphetamines reverse the same transporter
• nicotine stimulates Ach receptor neurons but these in turn stimulate dopaminergic neurons

Question 15

net effect of stimulants and risks

Answer 15

net effect: chronic dopamine flood into synapses and stimulation of dopamine receptors on target neurons

risk: unlike most drug-receptor interactions, those directly involving the dopamine system sensitize over time (contrast with tolerance) leading to greater desire

Question 16

dependence of depressants: baributates and benzodiazepines

Answer 16

• patient failure to adhere to prescribed doses can cause dependence
• CNS develops tolerance to BZs sedation over a few months - leads to withdrawal (esp. short-acting/high potency forms) pt escalates dose beyond the prescribed amount

Question 17

action of depressants

Answer 17

alcohol and barbiturate depressant actions are mediated by hyperexcitability of the inhibitory GABA receptors

be aware that both indirectly trigger the dopaminergic system

Question 18

receptors for endogenous opioids

Answer 18

• mu receptor prefers B-endorphin
• delta receptor prefers enkephalins
• kappa receptor prefers dynorphins

Question 19

drugs that act on the mu receptor

Answer 19

morphine
heroin
methadone

Question 19

action and onset of morphine withdrawal

Answer 19

morphine blocks cAMP secondary messenger production, neurons try to redress cAMP balance

when morphine absent, too much cAMP generated… this ‘sensitization’ induces withdrawal symptoms

Question 20

pharmacologically active components of marijuana/cannabis

Answer 20

• tetrahydrocannabinol (THC: main psychoactive ingredient)
• cannabidiol (CBD: relaxant/anti-inflammatory action)
• cannabinol (CBN: small psychoactive effect)

Question 21

marijuana/cannabis mode of action

Answer 21

act on cannabinoid receptors CB1 and CB2 which are located throughout the brain and peripherally and bind the endogenous signalling molecules ‘anandamide’ and ‘2-arachidonoylglycerol’

action via dopamine release

Question 22

experimental use of drugs

Answer 22

few occasions, curiosity, anticipation (short-lived)

Question 23

recreational use of drugs

Answer 23

variable pattern of use, compliments users social activities

no adverse social or medical consequences

largely confined to weekend use - perception of harm associated with use is variable and at times contraindicatory

Question 24

psychiatric co-morbidity

Answer 24

pharmacy services are geared towards substitution therapies (treatment of substance misuse) OR treatment of psychiatric morbidity (psychosis, depression)

Question 25

1st-degree psychiatric diagnosis

Answer 25

• enjoyment/relaxation
• self-medication/escape
• peer group acceptance
• psychosis and cannabis, stimulants
• affective disorders and alcohol, stimulants
• PTSD, anxiety disorders and alcohol

Question 26

1st degree substance misuse diagnosis

Answer 26

• genetic vulnerability/predisposition to psych illness
• dependent/chaotic lifestyle may act as precursor for mental health problems
• alcohol and depression, anxiety
• opiates and depression
• stimulants and depression, psychosis
• cannabis and depression, psychosis

Question 27

gender-specific issues

Answer 27

• women more likely to have experienced trauma/abuse (physical, sexual and emotional) leading to SM/co-morbidity - can lead to re-victimisation (fund habit through prostitution, further risk of trauma)
• women tend to seek help from services for psychological problems then substance misuse