Psychological medicine

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Diagnostic Criteria

  • Two types of disorder:
    • Substance use disorders: abuse and dependence 
    • Substance induced disorders: secondary to substance use (eg withdrawal, psychosis, persisting dementia or amnestic disorders, etc). Require evidence of substance use and are not related to pre-existing problems
  • Abuse vs. dependence: 
    • Abuse implies use is causing job, social, legal or physical problems or impairing function in some way
    • Dependence (a step worse) requires signs of withdrawal and tolerance
  • Used to be a definition for „the addictive personality type‟: but research has shown no consistent correlation with the proposed criteria

Substance Abuse

  • A maladaptive pattern of substance use leading to significant impairment or distress, manifested by one (ie fairly low threshold) or more of the following occurring in the same 12 month period:
    • Recurrent substance use resulting in a failure to fulfil major role obligations at work, school or home
    • Recurrent substance use in which it is physically hazardous (eg driving)
    • Recurrent substance-related legal problems (eg arrests for disorderly conduct) 
    • Continued use despite it causing or exacerbating persistent or recurrent social or interpersonal problems 
  • Symptoms have never meet the criteria for substance dependence for this class of substance

Substance Dependence

  • A maladaptive pattern of substance use leading to significant impairment or distress, manifested by three or more of the following occurring in the same 12 month period: 
    • Tolerance: either ­ amounts to achieve intoxication or diminished effect with same amount 
    • Withdrawal: either characteristic withdrawal syndrome for that substance, or the same or a closely related substance is taken to avoid withdrawal symptoms
    • Substance is taken in larger amounts or over a longer period than was intended
    • There is a persistent desire or unsuccessful efforts to cut down or control use
    • A great deal of time is spent obtaining, using or recovering from its effects
    • Important social, occupational or recreational activities are given up or reduced as a result 
    • Use is continued despite knowing that has caused or exacerbated a physical or psychological problem


  • 1986 CHCH Psychiatric Epidemiology Study: Lifetime prevalence rates:
  • Adolescents:
    • 5% of 15 year olds meet criteria for alcohol abuse (Fergusson 1994)
    • Cannabis dependence 7% at 18 years, 10% at 21 years.  Higher in males
  • Co-morbidity or Dual Diagnosis:
    • Epidemiologic Catchment Area (ECA) Study 1990 found the lifetime co-morbidity of substance use disorders by specific diagnoses:
  • Those with a mental disorder have twice the risk of an alcohol disorder and 4 times the risk of any other drug disorder
  • Those with a lifetime alcohol disorder have twice the risk of another mental disorder (37%) and 6 times the risk of another drug disorder (22%)
  • Those with a lifetime other drug disorder have a 4 times risk of another mental disorder (53%) and 7 times the risk of an alcohol disorder (47%)
  • Co-morbidity is higher in institutional settings (70- 80%) than in the community
  • Þ Dual diagnosis is an expectation not an exception

Models of Aetiology of Addiction

  • Disease model: emphasises the biological and genetic basis of addition. Loss of control is a central feature 
  • Self-medication hypothesis: use specific pharmacological effects to self medicate for psychological disturbance and painful affects
  • Biopsychosocial model: Multifactorial causality, interaction of genetic predisposition, biological factors, and psychological and sociocultural factors 
  • Biological model: impact on mesolimbic reward system – extends from the ventral tegmentum to the nucleus accumbens, with projections to areas such as the limbic system and the orbitofrontal cortex

Factors influencing behaviour*

  • Early childhood learning: modelling by parents and significant others
  • Current environment: reinforcement or punishment for different practices (especially if immediate)
  • Views/knowledge/beliefs about risk: usually over-rate our health and under-rate the risks
  • Our resources (usually an excuse)
  • Physical environment (work/home)
  • Social influences (friends/media)

History Taking

  • Attitude of interviewer important: non-judgemental, empathic, detached, normalising behaviour, start estimates of use at a high level, person can then say „no, not that much‟ – feels less judgemental
  • Often illegal: won‟t tell unless good rapport
  • Signs of Substance Abuse
    • Changed behaviour
    • Skipping work/school
    • Drug seeking behaviour
    • Money problems
    • Relationship problems
  • Questions:
    • Reason for presentation
    • Which drugs
    • Ever intravenous
    • What are the useful effects – why do you continue to use
    • Quantity and frequency, pattern of use (regular or binge)
    • Cost per week
    • Duration of use, age at first use, reason for first use
    • Heaviest use
    • Have you or others ever been concerned about your use
    • Attempts at cutting down and duration of abstinence, what made you start again
    • Problems associated with use, including relationships, job, legal considerations, etc
    • Any withdrawal effects
    • Past treatment and outcome, what was and wasn‟t helpful 
    • Relationship to psychiatric symptoms. Do they drink when they‟re anxious? Have panic attacks followed ­ drug use, etc
    • If alcohol, ever been in an accident, had a head injury or fracture
  • Medical history, psychological history, social situation
  • Family History: check psych, suicide and A&D history
  • Corroborative interview
  • Drug users have high mortality: health consequences, accidents, suicide, high-risk neighbourhoods, etc 
  • Physical examination: yellow fingers/teeth, injection marks, liver, cardiac murmurs, pregnancy/STD, mental status, signs of intoxification/withdrawal


  • Alcohol abuse: ethanol level, also LFT (­GGT) & FBC (macrocytes), nutrition (eg Fe)
  • Blood tests for drug levels: benzodiazepines & morphine levels
  • Cannabis: creatinine/cannabis ratio over time
  • If any intravenous use check for viral serology: Hep B, C, HIV
  • Urine tests: useful for tracking abstinence, but not reliably effective as a treatment strategy. Can do a full drug screen (drugs + prescription medications) for $160. Verification of sample source is important – minimise the risk of substitution (eg giving you someone else‟s urine sample).

Drugs of Abuse

  • If therapeutic index is wide, then it‟s good for addiction: good effect but few side effects 
  • IV drugs: opiates, speed, and benzodiazepines. Health risks include infection and non-infectious sequalae
  • Marijuana
  • Ecstasy – amphetamine (party scene)
  • Fantasy – GHBA
  • Solvents: younger, failing at school, worried parents, neurological impairment
  • Tobacco 

Dependence resulting from various drugs


  • Psycho active ingredient is D9 tetrahydrocannabinol (D9 THC)
  • Receptor targets in the CNS = CB1, in PNS = CB2
  • Synthetic cannabinoid drugs used therapeutically for appetite stimulation (eg in cancer), anticonvulsant/antispastic, analgesic
  • Effects:
    • Minimal for occasional use, greater for longer-term heavy use
    • Respiratory system: hot irritating smoke ® all the effects of cigarette smoke (inflammation, ­mucus, thickened basement membrane, squamous cell metaplasia, destruction of cilia)
    • CNS: enhanced feelings of well being, disputed dose-dependent effects – reduction in energy, drive and motivation, psychosis, ¯learning and attention, dependence with associated social and psychological dysfunction, acute adverse reactions (eg anxiety/panic attacks)

Treatment of Substance Abuse

Treatment Rationale

  • Treatment must be for underlying addictive disorder, not just detoxification and withdrawal 
  • Addiction is a chronic not acute illness. Requires long term follow-up and behaviour modification (as with diabetes and hypertension) 
  • Often unsympathetic response because addiction is perceived as self-afflicted: but there are numerous involuntary components in the addictive process. Loss of voluntary control turns a drug misuser into drug addicted. There is a compulsive, often overwhelming, involuntary component 
  • Involves genetic, biological, behavioural and environmental components
  • Success rate for treatment depends on type of drug and variables inherent in the population being treated (e.g. better for professionals than for poorly educated). Nicotine has the poorest success rate. Success rates are comparable with other chronic diseases 
  • Treatment is cost-effective

 Issues In Treatment

  • Compliance with treatment. Those who comply with treatment have best prognosis – as with other chronic diseases
  • Who should be involved: multidisciplinary approach 
  • Managing the environment: peer pressure, money, job, supports, triggers to former behaviour, family relationships (can they be helped, education about illness) 
  • The most significant predictor of treatment success is an empathic, hopeful, continuous treatment relationship
  • Must also treat any co-morbid diagnosis simultaneously

Types of Treatment

  • Medication: Antabuse, naltrexone, opioid substitution
  • Detoxification (inpatient/outpatient)
  • A&D counselling: motivational interviewing, strategies for change, relapse prevention
  • Psychotherapy: CBT, psycho-education
  • Self-help groups 
  • Addressing specific issues: grief, anxiety, childhood sexual abuse, sexual assault, anger, relationship problems, parenting issues, financial, housing, employment issues, etc

Readiness to Change/Motivational Interviewing

       See Topic: Behavioural Change

Services for dependency

  • Detox: Kenepuru (inpatient)
  • AA
  • Narcotics anonymous
  • Queen Mary – Hamner: uses 12 step process
  • Odyssey House (Auckland)
  • Alcohol and drug service

Making the change

  • Takes a long time
  • Involves changing lifestyles, supports, habits
  • GP can assist with motivation for change:

Methadone Treatment

  • For opiate addiction 
  • Methadone is highly addictive, but is regular, long acting (a dose a day holds for 24 – 46 hours), free ( ¯crime), legal, more effective taken orally than other opiates, no risks from injection
  • Doesn‟t give a high – just stops „hanging out‟ (withdrawal)
  • Has to be taken every day 
  • Can cause high mood, drowsiness, ¯pain, small pupils, constipation, histamine release (sweating, itching, etc), ¯saliva  ­tooth decay, ¯libido – it is a powerful drug 
  • It doesn‟t affect senses, or damage body organs, shouldn‟t affect pregnancy or breast-feeding 
  • Is dangerous in conjunction with tranquillisers and/or alcohol  overdose situation (eg vomit and choke while sedated) 
  • Is taken as part of a planned programme, including counselling, to build a life away from opiate abuse –       can concentrate on sorting out debt, relationships, etc
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