Lecture 31: Introduction to mental disorders and psychiatric epidemiology Flashcards
what makes mental disorders different from physical diseases?
- there is no independent biological test
- disorders are defined by clusters of mostly self-reported symptoms (depression, anxiety, substance use disorder), many of which are not obvious to observers
- depression, anxiety and substance use disorders are mostly not obvious, while bipolar disorder and psychotic disorder are more evident to others
- there is debate about whether disorders are quantitavely different from normal functioning (i.e. at one end of continuum) or qualitatively different (i.e a departure from normal experience)
- they are heavily stigmatised - people feel shame and judgement and are reluctant to seek help
what is the DSM-5 definition of a mental disorder?
- a syndrome characterised by clincally significant disturbance in an individuals cognition, emotional regulation or behaviour that reflects a dysfunction in the psychological, biological or developmental processes underlying mental functioning
- usually associated with significant distress or dysfunction in social, occupational or other important activties
what is the DSM?
The diagnositic and statistical manual of mental disorders (DSM)
- DSM is the first classification system to provide diagnostic criteria for mental disorders, with clear thresholds (type, number and duration of symptoms) for diagnosis
- This allowed for greater clinical reliability and clinical communication and the development of research diagnostic interview
- DSM has been criticised because of increasing number of disorders with each edition of DSM (now up to DSM-5) and high prevalence of disorders from psychiatric epidemiolgoy surveys.
what are the major categories of mental disorders?
- mood disorders (depressive and bipolar)
- anxiety disorders
- substance related disorders
- schizophrenia and psychotic disorders
- eating disorders
other: neurodevelopmental (autism, ADHD); disruptive behaviour/impulse control;sexual function; neurocognitive (dementia, delirium)
what are the symptoms of Major Depressive Disorder?
major depresive disorder needs 5/9 symptoms
- depressed mood (sad or empty) every day, most of the day, for at least 2 weeks
- reduced interest in activities that used to be enjoyed
- sleep disturbances (insomnia/sleeping too much)
- fatigue
- psychomotor retardation or agitation
- weight change
- difficulty concentrating, holding a conversation, paying attention or making decision
- feelings of worthlessness or excessive guilt
- suicidal thoughts or intentions
PLUS: cause significant distress/impairment
what are the symptoms of Bipolar Disorder (Mania)?
- abnormally elevated mood or irritbility
- inflated self esteem
- decreased need for sleep
- very talkative
- flight of ideas, thoughts racing
- increase in goal-directed activity (social, work, study)
- excessive involvement in pleasurable but risky activities (spending, sex etc)
what are the challenges of determining the prevalence of mental disorders in the population?
- health service data only tells you about those who have been in hospital or sought help.
but only the most severe cases go to hospital and only 1/3 of people with a disorder in any given year seek help - need to use surveys of the general population to estimate prevalence. but this is challenging as you can’t just ask people if they have a disorder. Even if they have symptoms, many people won’t necessarily recognise they have a disorder or which disorder
- people can also be reluctant to disclose due to stigma
how can cross-sectional studies be used?
Good for measuring current prevalence, but needs:
- a large sample for robust estimates in specific demographic groups, especially of low prevalence disorders
- a long interview (to ask about multiple symptoms of multiple disorders)
- a high response rate, to reduce bias
how can prospective studies be used?
usually smaller samples and restricted age range, but good for measuring risk factors
What is Te Rau Hinengaro: The New Zealand Mental Health Survey?
New Zealand’s first and only national mental health survey; 10 years in the planning
- it was a cross-sectional survey
- data collection over 12 months in 2004. 100 interviewers were employed
- sampling frame: the non-institutionalised general adults (16+) population
- Maori and Pacific were oversampled to ensure statistically robust estimates of disorders for these ethnic groups. 2x the number of Maori and 4x the number of pacific relative to population proportions
Sample:
12,992 (2595 Maori, 2236 Pacific)
- Respone rate: 73.3%
- *Interview:**
- fully structure psychiatric interview, administered face to face by trained interviewers
- screening questions for each disorder; full diagnostic assessment for those who endorsed the screening questions for a particular disorder
Most mental disorders were measured:
- but not schizophrenia due to sampling frame problem and self report but not sufficiently valid
Much other information collected including disorder history, childhood and traumatic experiences, physical health, functional impairment, SES, health service use
Interview duration
- if no mental health history: 45 mins, but much longer for those with mental disorders
What is the 1 month, 12 month and lifetime prevalence of mental disorders?
what is the life time prevalence of any DSM-5 disorder in the world mental health surveys?
USA has the highest prevalence of any DSM-5 mental disorder.
NZ is the 4th highest almost 21% prevalence
what are important things to consider about mental disorders?
- mental disorders are controversial because they cannot be independently verified and because their definitoin is constantly evolving
- they are nonetheless real and manifest as a profound disturbnace in psychological functioning that is hugely distressing and disabling
- they are also common, though how common is disputed. general population surveys are the best data we have
- NZ has relatively high rates of mental disorder
