Slides made to facilitate journal club discussion on cohort study looking at link between depression and violence in Swedish populations.

1. DEPRESSION AND
VIOLENCE: A SWEDISH
POPULATION STUDY
Dr. Sharma (FY2
Psychiatry)

3. PAPER DETAILS
• Background
• Methodology
• Results
• Conclusions

4. BACKGROUND
• Depression is associated with multiple
adverse outcomes
• Its association with violence outcomes is
not consistently demonstrated
• Important confounders include alcohol
and drug misuse, sociodemographic
factors, and psychosis
• Inclusion of inpatients distorts data

5. METHODOLOGICAL
APPROACH
Study 1
• Longitudinal follow-up of patients
with index diagnosis of depression
• Exclusion of inpatients
• Non-depressed siblings included to
determine extent of familial
confounding
Study 2
• Twin study
• Association between depressive
symptoms and violent crime

6. STUDY TYPE:
POPULATION COHORT

7. METHODOLOGY
1. Linkage of registers (patients identified using a unique 10-digit
code)
 National Patient (recording of outpatient data began in 2001)
 Multi-Generation (allowed for identification of siblings and half-
siblings)
 National Cause-of-Death
 Swedish Twin
 National Crime (conviction data for everyone aged >15 years)
2. Twin study
 Depressive symptoms measured using sCESD scale
• Informed consent was not required as data were merged and
anonymised by an independent agency

8. INCLUSION
CRITERIA
 Individuals born between 1958-1994,
followed from 2001 until 2009
 Must have had at least two outpatient
episodes of depression (coded using ICD)
 Twins aged 18-47 years old

9. EXCLUSION
CRITERIA
 Patients with inpatient episodes of depression
 Patients with in- or outpatient diagnoses of
schizophrenia, schizophrenia-spectrum and
bipolar disorder
 Patients with cormorbid personality disorder
 Crimes for which interpersonal violence cannot
have been determined to have occurred (only
homicide, attempted homicide and all forms
of assault)
 Crimes committed after 12 months from
diagnosis

10. STATISTICAL
ANALYSIS
Calculation of odds ratios
Regression analysis between
sCESD score and violent crime,
adjusted for age and sex

12. RESULTS (1)
o n = 47,158 individuals with outpatient diagnoses of depression
from 2001-2009
o 17, 249 men (36.6%) - mean age 32 years (S.D. 10 years)
o Incidence of crime in follow-up period = 3.7%
o 29, 909 women - mean age 31 years (S.D. 10 years)
o Incidence of crime in follow-up period = 0.5%
o Individuals with depression were at 3-fold increased
odds of violence compared with general population
controls, and at 2-fold increased odds compared with
unaffected siblings

13. RESULTS (2)
Relative risk of violence crime
between those with depression
and those without remained
significant even when history of
patients with violent and non-
violent crimes, self-harm and
substance use disorders were
excluded
However, presence of the above
factors increased absolute risk –
offending history had the largest
effect

14. RESULTS (3)
oOdds ratios for self-harm were
increased 5.7-fold as compared to
the general population
oTwin analysis showed a significant
increase risk between depressive
symptoms and risk of violence

15. DISCUSSION
➢ First family-based study of violence risk in depression
➢ Following adjustment for genetic and early environmental factors, a
diagnosis of depression modestly increases the risk of violent crime
➢ Impulse control and affect dysregulation may be potential
mechanisms whereby this association occurs
➢ Admitted patients, with severe depression, were excluded on basis of
implicitly increased risk
➢ Discussion largely focuses on introduction of violence risk assessment
into clinical practice

16. MCQ (1)
Which of the following factors was not included in sub-
analysis?
A. Age
B. Sex
C. History of psychosis
D. History of criminality
E. History of self-harm

17. MCQ (2)
Why did the analysis compare risk of violence between depressed
subjects with their family members?
A. To help assess and predict future risk of violence of family
members
B. To help exclude possible genetic and environmental confounding
factors as predictors of violence
C. To test the null hypothesis that the risk of violence between twins
and full siblings is identical
D. To identify whether parenting styles have an effect on violence
risk
E. To emphasise the importance of nature over nature

18. MCQ (3)
Which pre-existing factor was the strongest predictor for
violence in depressed individuals?
A. Drug and substance misuse
B. Immigrant status
C. History of non-violent crime
D. History of violent crime
E. Psychosis

19. MCQ (4)
What was the rate of violent crime in men in the combined risk
factor (substance abuse, self-harm and violent crime) subgroup?
A. 8.5%
B. 13.5%
C. 12.5%
D. 16.3%
E. 78.2%

20. MCQ (5)
What was the ratio of odds ratio (ROR) between female
patients with depression and their maternal half-siblings?
A. 3.0
B. 2.8
C. 2.3
D. 1.3
E. 1.2

21. CONCLUSION
1. This well-powered study demonstrates an association
between depression and violence risk.
2. The discussion neglects to inform us how these findings can
help us support offenders with coexistent depressive
symptoms, and makes no reference to development of a
compassionate care model.

22. DISCUSSION POINTERS
➢ Why have the authors done this piece of research?
➢ Why have the authors chosen this particular methodology? What
are its limitations?
➢ Do you think the study’s exclusion criteria were fair? Were the
authors right to exclude:
➢Inpatients?
➢Patients with co-existent personality disorders?
➢ Are the findings of this study generalisable to the U.K.
population?