The biological approach to explaining OCD Flashcards
(17 cards)
The COMT gene - What hormones does this gene regulate? (Tukel et al 2013)
The COMT gene is involved in the production of catechol-O-methyltransferase, or COMT, which regulates the production of dopamine. Dopamine has been implicated in OCD. Tukel et al (2013) found that a variation of the COMT gene produces lower activity of the gene and higher levels of dopamine in OCD patients.
The SERT gene - What hormone does this gene lower? (Ozaki et al 2003)
The SERT gene affects the transport of serotonin, creating lower levels of this neurotransmitter, which is implicated in OCD. Ozaki et al (2003) found a mutation in this gene in two unrelated families, where 6 of 7 family members had OCD.
Diathesis-Stress
The link between one gene and complex disorders like OCD is unlikely to be simple. The SERT gene is implicated in multiple disorders like depression and PTSD, indicating that each gene creates a vulnerability for OCD and other conditions. Other factors also affect whether any mental illness develops.
Neural Explanations
Neural explanations focus on the brain’s structure and neurotransmitter activity. Abnormalities in neurotransmitter levels and brain circuits are thought to contribute to OCD.
Abnormal Levels of Neurotransmitters (Piggot et al, 1990)
Dopamine levels are thought to be abnormally high in people with OCD. Animal studies show that high doses of dopamine-enhancing drugs lead to compulsive behaviors. Low levels of serotonin are also linked to OCD. Piggot et al (1990) found that antidepressants increasing serotonin activity reduce OCD symptoms.
Abnormal Brain Circuits
Certain brain areas, particularly the caudate nucleus in the frontal lobes, are thought to be abnormal in OCD patients. The caudate nucleus usually suppresses signals from the orbitofrontal cortex (OFC).
AO3 for Genetic and Neural Explanations
Various strengths and weaknesses in genetic and neural explanations of OCD can be discussed, including support from family studies, research on brain structures, and implications for real-world applications.
The Role of Genetic Factors Supported by Family Studies of OCD (Nestadt et al, 2003) - Weakness
Nestadt et al (2003) found that people with first-degree relatives who have OCD are at higher risk of developing the disorder. However, families typically share environments as well as genes, so environmental factors may also contribute to OCD development.
Tourette’s Syndrome and Other Factors (Strength) - Pauls and Leckham (1986)
Evidence for the role of genes in OCD comes from studies of people with other disorders. Pauls and Leckham (1986) found that obsessive behaviors in Tourette’s patients and their families suggest OCD and Tourette’s are expressions of the same gene. This supports the idea that OCD may be a predisposed behavior.
Studies Showing a Genetic Link to Brain Abnormalities in OCD Patients (Menzies et al, 2007) - Strength
Menzies et al (2007) found that people with OCD and their close relatives have reduced grey matter in key brain regions, including the OFC. This suggests that anatomical differences are inherited and may contribute to OCD.
Real-World Applications - Mapping of the Human Genome
The mapping of the human genome has led to hopes that specific genes could be linked to mental and physical disorders. For example, the COMT gene could be screened in embryos, offering parents a choice of whether to abort embryos with the gene. However, this raises ethical concerns about gene therapy and its application in mental health.
What AO3 Are You Using for Genetic Explanations of OCD?
Nestadt et al (2003) - Family & twin studies, Pauls and Leckham (1986) - Tourette’s syndrome, Menzies et al (2007) - Research on genes and OFC, Real-world application - Mapping of the human genome.
Concordance Rate
The concordance rate is a measure of genetic similarity in a sample, like 100 twin pairs. If one twin has a disorder, the concordance rate reflects how often the other twin also has the disorder. A 40% concordance rate means 40% of the time both twins share the disorder.
Dopamine
Dopamine is a neurotransmitter that affects motivation and drive. Abnormal dopamine levels are linked to OCD, with high levels potentially leading to compulsive behaviors.
Gene
A gene is a section of a chromosome that carries genetic information in the form of DNA. Genes play a crucial role in inherited traits and may contribute to disorders like OCD.
What Does OFC Stand For?
OFC stands for the Orbitofrontal Cortex, a brain region involved in decision-making and behavior regulation. Abnormalities in the OFC are implicated in OCD.
What is Different About the OFC in People with OCD? How Do Low Levels of a Certain Hormone Affect This? How Would High Levels Affect the Basal Ganglia?
In people with OCD, the OFC and caudate nucleus are abnormal. Low levels of serotonin may cause these areas to malfunction, while high levels of dopamine can lead to overactivity of the basal ganglia, which contributes to compulsive behavior.
