Weissman et al (2005) - Genetic Similarity

Question 1

Aim

Answer 1

To study the potential genetic nature of Major Depressive Disorder

Question 2

Sample

Answer 2

Weissman et al (2005) carried out a longitudinal kinship study with a sample of 161 grandchildren and their parents and grandparents to study the potential genetic nature of Major Depressive Disorder.

Question 3

Method

Answer 3

The study took place over a twenty-year period, looking at families at high and low risk for depression. The original sample of depressed patients (now, the grandparents) was selected from an outpatient clinic with a specialisation in the treatment of mood disorders.

The non-depressed participants were selected from the same local community. The original sample of parents and children were interviewed four times during this period. The children are now adults and have children of their own - allowing for the study of the third generation.

Data was collected from clinicians, blind to past diagnosis of depression or to data collected in previous interviews. Children were evaluated by two experienced clinicians - a child psychiatrist and a psychologist.

Question 4

Results

Answer 4

The researchers found high rates of psychiatric disorders in the grandchildren with two generations of major depression. By 12-years-old, 59.2% of the grandchildren were already showing signs of a psychiatric disorder - most commonly anxiety disorders.

Children had an increased risk of any disorder if depression was observed in both the grandparents and the parents, compared to children where their parents were not depressed. In addition, the severity of a parent’s depression was correlated with an increased rate of mood disorders in the children.

On the other hand, if a parent was depressed but there was no history of depression in the grandparents, there was no significant effect of parental depression on the grandchildren.

Question 5

Evaluation

Answer 5

The study is longitudinal, increasing the reliability of the data.

The use of researcher triangulation increases the credibility of the findings.

A sample of 161 children is a large sample; however, more research would need to be carried out to confirm the reliability of the findings.

Although family (kinship) studies indicate a potential genetic link to behaviour, there is no actual genotype studied.