Does the City Drive Us Mad?

The Effect of High Density Living

www.psychlotron.org.uk

Edexcel Specification

Candidates should be able to…describe and assess the effects of high density living on humans Data interpretation Drawing conclusions Exam technique

Urban Living and Mental Illness

What is the nature of the relationship?

Cause or effect? What is the

mechanism?

Urbanicity and Schizophrenia

Schizophrenia Risk and Urban Density

0

0.5

1

1.5

2

2.5

Rural Smalltown

Largetown

Small city Capitalsuburb

Capital

Type of Settlement

Risk

Pedersen & Mortensen (2001)

As population density rises, so does prevalence of schizophrenia

Risk in inner city more than twice that in rural area

Urbanicity and Schizophrenia

Higher density living is associated with increased risk of mental illness

Primarily schizophrenia, but also depression and anxiety

These data are correlational

Cause or Effect?

Causation Hypothesis

Something to do with the urban environment causes or triggers schizophrenia

Migration Hypothesis

People with schizophrenia move towards urban areas

Access to services, cheaper housing etc.

Cause or Effect?

Effect of Change of Residence on Schizophrenia Risk

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Baseline 5 years later

Moved to higherpopulation density

Moved to lowerpopulation density

Pedersen & Mortensen (2001)

Moving into or out of a city affects a person’s risk of schizophrenia

Cause or Effect?

Pedersen & Mortensen (2001)

Dose-response relationship between urban living and schizophrenia

More exposure in childhood leads to greater risk

Urbanicity Exposure & Schizophrenia Risk

0

0.5

1

1.5

2

2.5

3

3.5

0-4 years 5-9 years 10-14 years

Years of childhood exposure

Rel

ativ

e ris

k of

sch

izop

hren

ia

Capital

Suburb

Cause or Effect?

Relationship between urbanicity and schizophrenia cannot be explained solely by migration

Urban living plays a causal role in onset of schizophrenia

So what is the mechanism?

What is the Mechanism?

Urban Living Schizophrenia

Physical Stress e.g. noise, pollution

Biological risk factor e.g. viral

infection

Social Stress e.g. lack of

support

What is the Mechanism?

More evidenceLess evidence

Viral infection

Crowding Social isolation &

fragmentation

Pollution Social inequality

Daily life stress

Based on Freeman (1994); Pedersen & Mortensen (2001); van Os (2004)

Conclusions

People living in urban environments run a greater risk of developing schizophrenia

This is not due to migration of schizophrenics to inner cities

This may be due to infection or environmental stress (noise, pollution)

More likely due to the social conditions that accompany high density living