enviornmental factors

1. Dr Sardar Jaydev Kumar Deo
SR SCBMCH,Cuttack
Schizophrenia
Part-1

2. Risk Factors for the Onset of
Schizophrenia
Environmental
Ref:Kaplan and sadock”s synopsis of psychiatry,11th edition

3. Risk Factors Operating During Early Development
Paternal Age.
 -advanced paternal age
 -around three to four times in the offspring of fathers
who are older than 50, at the time of conception
Season of Birth.
 -Winter birth in people
 -Hypotheses
 -exposure to intrauterine viral infections
 -variation in light, temperature/weather,
 -external toxins.
 -the effect size increases with latitude .

4. Three main categories (small effect on the risk ) have significance:
1. Abnormal fetal growth and development:
 Lowbirthweight,
 Congenital malformations, and
 Small head circumference.
2. Complications of pregnancy:
 Bleeding,
 Pre-eclampsia,
 Diabetes, and
 Rh incompatibility.
3. Complications of delivery:
 Asphyxia,
 Uterine-atony, and
 Emergency cesarean section.
Pregnancy and Birth Complications

5. RISKFACTORS OPERATING DURING CHILDHOOD AND ADOLESCENCE
Urban Birth and Upbringing
 Association between urban living and rates of schizophrenia
and non-affective psychosis.
 Twofold increase in risk of schizophrenia in urban as compared
to rural settings.
 Unidirectional increasing rates of schizophrenia with
increasing levels of urbanicity.
 Urban exposure prior to the onset of the disorder is more
important than the level of exposure at the time of onset.
 People conceived (including period of gestational development)
in urban areas but reared in less urban areas may be at higher
risk of schizophrenia.
 Earlier age of onset In people exposed to urban upbringing.

6. URBAN UPBRINGING EFFECT?
 Material deprivation  risk of schizophrenia,
 Area level social fragmentation influence strongly the rates of
schiz.
 Neighborhoods with rich social capital (interpersonal trust,
norms of reciprocity, mutual aid) reduced rates of schiz.
 The higher the area’s ethnic density, the lower the rates of
schizophrenia in them.

7.  Increased rates of schizophrenia in migrants, especially among
the second generation born in the new home-land.
 There was also a higher risk of schizophrenia in migrants from
developing countries; however,
 The most conspicuous finding was the increased risk
associated with being black,
 A possible gene–environment interaction.
Migration

8.  Demonstrated higher rates of cannabis use among patients
with schizophrenia
 Consistent finding across studies: prior cannabis use 
subsequent psychosis .
 Men who used cannabis during adolescence had a significantly
lower age of onset.
 Individuals homozygous for the COMT valine allele  exposure
to cannabis schizophreniform disorder in adult life .
Cannabis Use

9. STRESSFULLIFEEVENTS AND EARLY CHILDHOOD TRAUMA
Studies report an excess of stressful life events in
the few weeks prior to the onset of psychotic and
affective disorders.
 ??? increased stress is a cause or a consequence
in the development of psychotic disorder.
Early childhood trauma (including sexual, physical
and emotional abuse, and neglect).the risk of
psychotic experiences is increased
Gene–environmental interaction.

10. PREMORBID
VULNERABILITY
INDICATORS

11. Premorbid Indicators: Early Developmental
Abnormalities
 Developmental abnormalities  most useful as a possible
measurable indicator of genetic liability for schizophrenia.
 Subtle motor/language, cognitive abnormalities.
 Abnormalities in motor milestones most conspicuous before the
age of 2.
 Receptive language abnormalities are most prominent between
the ages of 5 and 15.
 The relationship between the age of acquiring motor/language
milestones and risk of schizophrenia appears to be linear,
 The early emerging motor and language deficits appear to be
relatively specific for schizophrenia.
 As a group show signs of subtle social maladjustment- poor
relationships with other children, social isolation, lone play, and
social anxiety as compared to their peers.

12. Premorbid Indicators: Psychopathology
Findings clearly demonstrate significant psychopathology prior to adult
onset psychosis.
Anxiety, depression,
and antisocial
Disorders.
Schizophreniform
disorder
Anxiety, depression,
conduct/
Oppositional disorder,
ADHD
Anxiety, depression,
and antisocial
Disorders
Childhood
11 to 15
Adult
Syndrome
continuity
No Syndrome
continuity

13. Vulnerability markers (or even precursors):
 Evidence that early subclinical psychotic experiences  later
Development of psychotic disorders .
 Dose–response relationship between number of subclinical
psychotic experiences and the transition to clinical psychosis
(risk of around 30 )
 Evidence from general population studies subclinical
psychotic experiences are relatively common (prevalence 15 %).
 Most are brief, self-limiting developmental phenomena +
known risk Factors (cannabis, urban upbringing, and developmental trauma). 
abnormally persistent onset of psychotic disorders .
Subclinical Psychotic Experiences

14. A dynamic model of psychosis evolution /
Proneness-Persistence-Impairment Model
Developmental expression of psychosis liability
(transient subclinical psychotic symptoms)  more
intrusive persistent subclinical psychotic symptoms 
significant impairment and dysfunction
eventual onset of psychotic disorder.

15. Proneness-
Persistence
-Impairment
Model
Developmental
expression of
psychosis
liability (transient
subclinical
psychotic
symptoms)
More
intrusive
persistent
subclinical
psychotic
symptoms
Significant
impairment
and
dysfunction
Onset of
psychotic
disorder.