1. Biological Explanations of Schizophrenia – Genetics
There are 3 main explanations of schizophrenia put forward by the biological model
1. __________________________________
2. __________________________________
3. __________________________________
The genetic explanation states that schizophrenia is passed from one generation to the next
through our __________.
What kind of studies would researchers conduct
to investigate a biological aspect of
schizophrenia? Some of these studies aim to establish
a concordance rate – what is this?
i) _________________________________
ii) Twin studies
iii) _________________________________
iv) _________________________________
i) _______________Studies
A01 – Kendler et al
A02 – Gottesman (1991) provided support for the genetic
(_______) found that
explanation of schizophrenia.
__________-
___________ relatives of 1. _________ ___________________ = 46% risk
those with schizophrenia
were 18 times more at risk 2. One parent = ______% risk
of developing the disorder.
3. _______________________ = 8% risk
4. Grandparent = _____% risk
A02 –
5. There is also a 17% chance of developing schizophrenia in families
where the identical twin of one parent has schizophrenia (this shows
A02 – the influence of __________________ over ________________).
A02 –

2. ii) Twin Studies
A02 – The research by Gottesman (1991) & Shields
A01 – Gottesman (1991)
(1962) suggests…
Reviewed 40 twin studies and
found a concordance rate of:
________% for MZ twins
and A02 – negative symptoms show a stronger genetic
component than positive symptoms…
________% for DZ twins
A02 – concordance rates not 100%
A01 – _____________ (1962)
Found concordance rates were
similar for MZ twins raised A02 – 2/3 of patients have no family history…
together to those raised apart.
iii) _______________Studies
Adoption studies allow
the researchers to A02 – Tienari (1991) studied ______ adopted children whose
separate _______________ biological _______________ was diagnosed with schizophrenia
from __________________ (group 1) and compared them with a matched group of adopted
children who had no family history of schizophrenia (group 2).
Tienari found that - 10% of the adopted group 1 had developed
A01 – Kety (1994)
schizophrenia
Found high rates of - 1% of the adopted group 2 had developed
schizophrenia in people whose schizophrenia
biological parents had the
disorder but who had been However is it likely that the children would have spent all
adopted by psychologically
of their childhood apart?
healthy parents.
iv) Gene Mapping
A01 – Sherrington et al A02 – Reductionist
(1988) a gene on
chromosome 5
has been linked to
schizophrenia