OCD

Genetic explanation

Genetic explanation

• Supporting research - Gerald Nestadt

• Supporting research again - Nestadt

• Not entirely sure which genes are involved

Genetic explanation - Research supporting (Twins)

E: Gerald Nestadt et al reviewed twin studies and found that 68% of identical monozygotic twins developed OCD as opposed to 31% of non identical dizygotic twins. 

E: MZ twins share 100% of their genes, whereas DZ twins only share around 50%, meaning the higher concordance rate suggests that genetic factors contribute to the development of OCD. 

L: Therefore, the genetic explanation is an accurate explanation for OCD. 

CA: However, the concordance rates with MZ twins are never 100%. This shows that there must be other factors that are also involved such as environmental influences. This is because of the diathesis stress model, which suggests that to have OCD, a person should not only have inherited genetic vulnerability, but also have a traumatic event that acts as a trigger. 

L: Therefore, while the evidence supports a genetic contribution, it also suggests that OCD is likely the result of an interaction between genetic and environmental factors.

Explanation - research supporting (familiy)

E: Nestadt identified 80 patients with OCD and 343 of their first degree relatives, and compared them with control patients that didn’t have OCD and their first degree relatives. They found that people with a first degree relative that had OCD had a 5x greater risk of having OCD themselves compared to the general population. 

E: This suggests that OCD runs in families, which is consistent with the idea that genetic inheritance increases vulnerability to the disorder. 

CA: However family members also share similar environments meaning the increased risk could partly be explained by shared environmental factors rather than genetics alone. 

L: Therefore, while the findings support the genetic explanation, they cannot conclusively separate genetic influences from environmental ones.

Explanation - not entirely sure which genes are involved

E:  Although several candidate genes have been proposed, researchers now believe that OCD is polygenic, meaning it involves many different genes.

E:  Each gene may only increase the risk of OCD by a small amount, making it difficult to determine which specific genes are responsible. This reduces the practical usefulness of the explanation, as identifying people who are genetically at risk becomes more complex.

L: Therefore, although genetics clearly play a role in OCD, the inability to pinpoint specific genes limits the explanatory power of the genetic account.