van der Wal, J. M., (2021). Advancing urban mental health research: From complexity science to actionable targets for intervention.

Question 1

background

Answer 1

Urbanisation and common mental disorders (CMDs; ie, depressive, anxiety, and substance use disorders) are increasing worldwide. In this Review, we discuss how urbanicity and risk of CMDs relate to each other and call for a complexity science approach to advance understanding of this interrelationship.

Question 2

cmd =

Answer 2

common mental disorder

Question 3

relatie tussen CMD and urbization

Answer 3

they found a positive, non-linear relationship with a higher CMD prevalence in more urbanised countries, particularly for anxiety disorders.

Question 4

We argue that factors in the urban
environment are likely to operate as a complex system and interact with each other and with individual city inhabitants (including their psychological and neurobiological characteristics) to shape mental health in an urban context. These interactions operate on various timescales and show feedback loop mechanisms, rendering system behaviour characterised by non-linearity that is hard to predict over time

Answer 4

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Question 5

two major events at the beginning of the 21st century that affect human society

Answer 5

• unprecedented increase in urbanization
• burden of mental disorders has increased

Question 6

By contrast, a meta-analysis of population surveys done in the USA22 between 2009 and 2011 found no urban–rural differences
for major depression in adolescents (n=55 583) and the
highest risk of major depression in adults (n=116 459) in small metropolitan and semi-rural areas.

Results for substance use disorders are mixed, partly because of the wide variety of substances and differences in availability or legal status.

Answer 6

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Question 7

hoe kan het dat bv. crime leidt tot meer internalising disorders

Answer 7

frequent exposure to negative circumstances such as inequality or crime in disadvantaged urban areas can lead to maladaptive appraisal in the form of negative selfevaluation or heightened perceived threats, increasing the risk of internalising disorders.

This weighted perception can further increase maladaptive behaviours, such as social isolation or illicit substance use, which will feed back to the urban environment (eg, by affecting neighbourhood social cohesion or crime).

Question 8

cities and stress

Answer 8

Cities are generally associated with prolonged exposure to social stress, which can alter the stress response. Accumulation of stressors has a negative effect on
neurobiological stress resilience (ie, allostasis), modifying the risk to develop CMDs throughout life

Question 9

Complex system behaviour in CMDs can be found in the occurrence of sudden deterioration of symptoms, characterised as sudden transitions around tipping points from a healthy to a pathological state.

Underlying dynamics could consist of reinforcing symptom feedback loops (eg, rumination and sleep) or
contributors to mental disorders (eg, poor diet and insufficient physical exercise)

Answer 9

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Question 10

the conceptual framework is based on 4 principles:

Answer 10

(1) the factors and outcomes involved operate as dynamically interacting elements within a complex system,
(2) factors are affected by metafactors such as changes in city size, urbanisation, migration, and stage of economic development,
(3) interactions between explanatory factors and CMD symptoms occur over different timescales, and
(4) CMD outcomes can affect explanatory factors (feedback loops).

Question 11

meta factors

Answer 11

• city size
• population growth
• urbanisation
• migration
• economic development

Question 12

factors

Answer 12

• urban
• social
• individual

Question 13

temporal scale

Answer 13

• years to throughout life
• weeks to months
• hours to days

Question 14

Our example concerns Jane, an inhabitant of a neighbourhood with little green space (urban factor), in her country’s largest city (meta factor). Her apartment
is located close to a busy road. Jane has a low income, which often causes financial distress (individual factor). The constant traffic noise (urban factor) disturbs her sleep, causing insomnia.78 Chronic exposure to air pollutants (urban factor) could negatively affect brain structures and functioning,48 increasing her risk of developing a CMD. Insomnia could increase financial distress by negatively affecting work performance, creating a reinforcing feedback loop.79 Depending on Jane’s psychological coping and neurobiological susceptibility, these factors could trigger, for example, a depressive disorder.79 However, her municipality is investing in sustainable urban development (meta factor) and building a park (protective urban factor) between her apartment building and the busy road. This intervention could improve Jane’s mental health by reducing stress (individual factor)63 and mitigating traffic noise (urban factors) in the short term,80 and eventually by increasing neighbourhood social cohesion (social factor)81 or perhaps even by mitigating air pollution (urban factor).82 This
hypothetical example shows how multiple interactions, from the urban to the individual level, can trigger CMD symptoms, create feedback loops, and reinforce distress. It also exemplifies how interventions can affect multiple
pathways over different timescales

Answer 14

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Question 15

The global population is increasingly living in urban environments. This demographic shift means there is
an increase in exposure to urban stressors that have been associated with higher risk of CMDs.

Answer 15

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