Week 5 Lecture 5 - substance use and MH comorbidity 1

Question 1

What are some consequences of substance use?

Answer 1

physical health:
- direct –> liver, heart and lung damage
- indirect –> illness, injury, self-neglect

financial:
- cost of use, loss of income due to intoxication and after effects

social and interpersonal:
- conflict with others
- poor educational attainment

mental health:
- transient psychosis
- depression and anxiety
- for people with established illness –> more/worse symptoms, poorer functioning, more relapse, increased suicidality

societal and economic burden:
- rising NHS and welfare costs
- criminal activity

Question 2

How common is substance use disorder?

Answer 2

• Estimates vary between settings and geographical location (e.g. London versus Rural Wales)
• Comparisons hampered by methodological differences (study design; sample; how substance use defined)
• UK: Not known how many people with SUD diagnosis

alcohol use disorder estimate = approx. 600,000 (1%)

Question 3

How prevalent are drugs in England and Wales?

Answer 3

• 35% of adults aged 16 to 59 had taken drugs at some point during their lifetime.
• 1 in 11 (9%) adults aged 16 to 59 had taken an illicit drug in the last year (3.2 million people).
• 1 in 5 (21%) young adults aged 16 to 24 had taken an illicit drug in the last year; 4.3% classed as ‘frequent” drug users (at least monthly use)
• Drug use fell 1995-2013 but is now rising again, with a large portion of the increase resulting from increased use of class A drugs in 16-24 year olds (largely MDMA/ecstasy and powdered cocaine)

Question 4

How prevalent is alcohol in the UK?

Answer 4

• 65% of men and 50% of women had drunk alcohol in past week
  Prevalence increases with age (up to 75)
• 38% of men and 19% of women aged 55-64 drinking ‘above safe limits’ (14 units +)
• More people ‘never’ drinking increasing and binge drinking decreasing, particularly among young adults

Question 5

Is there variation in prevalence in drug and alcohol use?

Answer 5

Yes

• Some groups more likely to drink problematically / use illicit substances than others (young people, especially students; people with mental health problems)
• Drug-related hospital admissions are five times more likely in the most deprived areas.

Question 6

What is comorbidity?

Answer 6

When two disorders or illnesses occur simultaneously in the same person

Question 7

What is dual diagnosis?

Answer 7

term used to describe people with both severe mental illness (mainly psychotic disorders) and problematic drug and/or alcohol use - “Dually diagnosed”

Question 8

What do epidemiological studies of the lifetime prevalence of SUD consistently report?

Answer 8

report higher rates of substance use (lifetime & current) in psychosis samples than general population (UK and elsewhere)

Question 9

What are 4 potential causes of comorbidity for SUD and psychosis?

Answer 9

• Substance use causes psychosis
• Substance use a consequence of psychosis (self-medication)
• Common origin (e.g. genetic vulnerability)
• Bidirectional – psychosis and substance use interact and maintain one another

Question 10

What evidence is there that suggests that some substances cause transient psychosis?

Answer 10

• Amphetamine, cocaine and cannabis -induced psychosis
• Experimental work with the main psychoactive ingredient of cannabis - tetrahydrocannabinol (THC) e.g. D’Souza et al (2004;2005)
• THC produces schizophrenia-like positive symptoms in healthy individuals
• THC transiently increases symptoms in people with schizophrenia
• People with schizophrenia are more vulnerable to the effects of THC

Question 11

What evidence is there that suggests that substance use (cannabis) often precedes psychotic symptoms from longitudinal prospective cohort?

Answer 11

Andreasson et al (1987):
- 50+ uses of cannabis use pre18 meant a 6x greater likelihood of hospitalisation for Schizophrenia at age 33

Birth cohort study started in 1970s:
- Assessed childhood symptoms prior to cannabis (age 11) ; cannabis at 15 & 18; Sz symptoms at 26
- Users of cannabis before 15 had more Sz symptoms at 26
- Genetic predisposition moderated risk adolescents with COMT polymorphism (Val allele) 10x more likely to have schizophreniform disorder aged 26

Question 12

What evidence is there to suggest that people with psychosis report using substances to self-medicate?

Answer 12

• Over half of people use substances when they feel paranoid
• Over half use it when they hear voices
• 38% use it when they are experiencing medication side effects
• Main reasons for use - Gregg et al (2009)
• feeling stressed, wanting to relax, when they are bored

Question 13

What evidence is there that suggests that genetic factors may predispose individuals to both mental illness and substance use?

Answer 13

• Adolescents with COMT polymorphism (Val allele) –> 10x more likely to have schizophreniform disorder at age 26

Substance use may precipitate psychosis i.e. may cause psychosis in people who would have developed it anyway (more susceptible to psychotogenic effects)

Question 14

Which potential cause of comorbidity between psychosis and SUD is most likely correct?

Answer 14

Bidirectional – psychosis and substance use interact and maintain one another

Question 15

Does substance use cause psychosis?

Answer 15

• Simple causal models too simplistic
• Most likely explanation is that the relationship is bidirectional with multiple risk factors (genetic, environmental, individual differences) playing a part