Recent Advances in the Neurobiology of Schizophrenia

Table 1.

Risk Factors for Schizophrenia and Their Effect Sizes

Category	Specific	Effect size
^a Relative risk;
^b Odds ratio.
After McDonald and Murray, Brain Res. Brain Res. Rev. 31, 130–137 (2000).
Genetic^a	MZ twin	45
	DZ twin or sibling	5
Early envirornmental^b	Obsteric complications	2
	Maternal infection	2
	City birth	1.4
	Later winter/spring birth	1.1
Late environmental^b	Immigrant status	4
	Chronic cannabis abuse	2
	Adverse life events	1.5
	Stress	1.5