Oruc et al. (1997)

Question 1

Aim

Answer 1

To investigate whether the genes encoding for certain serotonin receptors and serotonin transporters could be involved in suceptibility to bipolar disorder.

Question 2

Participants

Answer 2

• 42 people with bipolar disorders.
• 40 people with no health/mental disorders.
• Aged 31-70 years-old.
• 25 female, 17 male.
• From 2 Croatian hospitals.

Question 3

Method

Answer 3

Correlational study with a matched pairs design.

Question 4

How were ppts matched?

Answer 4

Ppts in the control group matched the patients in the other group in terms of age and gender.

Question 5

Why were DNA tests carried out?

Answer 5

To test for polymorphisms in serotonin receptor (5-HTR2c) and the serotonin transporter (5-HTT) genes.

Question 6

How were ppts tested for their genes?

Answer 6

Using a DNA test.

Question 7

Polymorphisms

Answer 7

A variation in a gene.

Rather than saying ‘mutation’ which suggests a unique change, polymorphisms refer to the different expressions that may be present in a normal population, even if that expression occurs infrequently.

Question 8

Why were the 5-HTR2c and 5-HTT genes chosen to be tested?

Answer 8

Since alteration in them can lead to disturbance in specific biochemical pathways, with known links to depressive disorders.

Question 9

In the bipolar group, what percentage had at least 1 first-degree relative with a mood disorder?

What was this compared to with the control group.

Answer 9

38%.

Compared to 0% in the control group.

Question 10

When were the S and 1 alleles more common?

Answer 10

In diagnosed females than healthy female controls.

Question 11

Sexually dimorphic

Answer 11

Any difference between males/females of any species which are not just differences in organs or genitalia.

These differences are cause by inheriting either male or female patterns of genetic material.

Question 12

Conclusion

Answer 12

S and 1 variants of the 5-HTR2c and 5-HTT genes may increase depression risk in females.

Question 13

Strengths

Answer 13

• Valid = 2 experienced psychiatrists verified whether ppts had bipolar or not using a structured interview schedule.
• Reliable = other studies had the same results for both genes. e.g. Gutierrez et al. (1996).
• Objective = DNA tests were analysed in a lab setting with automated equipment and so could not be biased.

Question 14

Criticisms

Answer 14

• Subjective = self-report questionnaires could lead to demand characteristics/social desirability bias.
• Correlational = cause/effect could not be determined.
• Low generalisability = limited sample size and age was an extraneous variable.

Question 15

How is the biological explanation deterministic?

How does Oruc’s study conflict this?

Answer 15

We cannot change our DNA.

However, Oruc’s findings show a small genetic susceptibility for females, so there must be other causes of the disorder.