Biological Explanations: The Brain and Biochemical Factors

A an enormous amount of biological research has been conducted to determine the aetiology of obsessive-compulsive disorder, it has revealed significant biological differences between the brains of people diagnosed with OCD and those without an OCD diagnosis:

• The activity of serotonin is lower in those diagnosed with OCD
• People with OCD show abnormal functioning in the orbital region of the frontal cortex and/or the caudate nuclei.

Serotonin

By chance, clinical researchers, such as Ananth (1983), discovered that obsessive and compulsive symptoms were reduced by the antidepressant drug clomipramine. Clomipramine is used to treat depression by increasing the activity of serotonin in the brain; however, it was found that it also reduces obsessive and compulsive symptoms. This indicates that OCD may be caused by low serotonin levels (Altemus et al, 1993). However, many disorders are associated with low serotonin levels. There must also be additional factors that contribute to the disorder.

Abnormal functioning of the orbital frontal cortex and caudate nuclei

These areas of the brain form a circuit that controls the conversion of sensory input into cognitions and actions. The orbital region of the frontal cortex seems to be involved in the production of primitive impulses such as bodily excretion, sexuality and violence. Nerve fibres carry these impulses to the caudate nuclei for possible translation into action. The caudate nuclei act as filter that allows the most powerful impulses to the thalamus. If signals reach the thalamus the person becomes consciously aware of these impulses.

Many biological theorists believe that the caudate nuclei or the the orbital region (or both) function too actively, thus allowing troublesome thoughts and actions to break through to conscious awareness. Symptoms of OCD often arise or subside when damage occurs in either area due to accident or illness (Paradis et al, 1992).

Click here for an example (scroll down to: 'Behavioral Changes in People Who Have Suffered From Frontal Lobe Injuries')

Further evidence for the role of this circuit is that PET scans have revealed more rapid glucose metabolism in OCD participants than controls (Baxter et al, 1990). Moreover, successful treatment results in a lowering of glucose metabolism in these areas, whereas patients who do not respond well show no such decline in glucose metabolism.

Could there be a link between low serotonin and the orbital frontal cortex – caudate nucleus circuit?

Serotonin plays a “very active role” in the orbital frontal cortex and the caudate nucleus (Comer, 1995). Low serotonin levels may well lead to abnormal functioning in these regions. Many theorists believe that these abnormalities create a predisposition for development of the disorder (e.g., Rappoport, 1991).

Psychodynamic Explanations

As with other disorders, the Psychodynamic approach explains OCD as the result of psychodynamic conflicts that arise during childhood; with OCD the main conflict is between the id and the ego. The id produces impulses that provoke anxiety, while the ego tries to reduce the anxiety by using defence mechanisms. Id impulses can take the form of obsessive thoughts and the ego defence mechanisms take the form of counterthoughts or compulsive behaviour.

Some defence mechanisms that are common in OCD:

Undoing

This is an attempt to 'undo' the threatening or negative thought

e.g., compulsive handwashing after touching something 'dirty'.

Reaction Formation

This is taking a radically opposite point of view to one's negative impulses

e.g., an OCD sufferer who has sexual thoughts takes up an obsessively puritan stance

Isolation (intellectualisation)

This is isolating thoughts from emotions, keeping the focus on facts and reason in order to protect oneself from something that is upsetting

e.g., a person who suffers from OCD may learn a great deal of facts and statistics about something that causes them anxiety.


Freud believed that OCD is the result of fixation at the anal stage of development, when children are going through toilet training. Children at this stage are obtaining their sexual gratification from bowel movements, while their parents are trying to teach them to delay this gratification. If parents overuse punishment, or are too harsh when toilet training children may develop aggressive id impulses and become messy, aggressive and stubborn. If parents deal with this by making the child feel shameful and dirty they will then have a counter-desire to control the id impulses. The result of this is an anally retentive personality (being messy is equivalent to passing faeces – being tidy is equivalent to retaining faeces). The obsessions, therefore, come from the desire to be messy, while the compulsions come from the need to control this desire.

cognitive-Behavioural Explanations

Cognitive-Behavioural theorists propose that everyone has repetitive, unwanted, unpleasant and intrusive thoughts, such as harming others, engaging in unacceptable sexual acts or being contaminated by germs (Rachman, 1993). Most people dismiss these thoughts as meaningless and ignore them. Those who develop the disorder hold themselves responsible and reprehensible for having these terrible thoughts. They worry that the thoughts will lead to harmful acts or that the thoughts themselves will lead to terrible consequences. This is the cognitive aspect of the disorder.

Because OCD sufferers find these thoughts so disturbing, they try to eliminate them by neutralising. That is, thinking or behaving in ways that will put matters right internally. They may, for instance, respond by thinking “good thoughts”, asking for reassurance from others or washing their hands.

When the neutralising strategy reduces the anxiety level of the individual it is reinforcing: it is more likely to be repeated in the future. The act is repeated so often that it becomes an obsession or compulsion. When the neutralising strategy seems effective it confirms the idea that the intrusive thought was dangerous or morally reprehensible and in need of elimination. This is the behavioural aspect of the disorder.

Because of this the thought, when it occurs again, is even more distressing and occurs even more frequently. If intrusive, negative thoughts are universal, however, this does not explain why some people develop the disorder, while others do not. A number of researchers, nevertheless, have identified several factors in those who develop the disorder:

Depressed Mood

Those prone to developing OCD tend to be more depressed than others. Clarke & Purdon (1993) found that depressed mood increases the number and intensity of intrusive thoughts. Other researchers have found similar results (e.g., Conway et al, 1991).

Strict code of acceptability

Many OCD sufferers have very high standards of acceptability regarding conduct and morality. Sexual and aggressive thoughts in this case are very disturbing, especially as they also tend to believe that bad thoughts are the same as bad acts [e.g., thinking about hurting someone is the same as doing it] (Rachman, 1993).

Dysfunctional beliefs about responsibility and harm.

People who develop OCD believe that the thoughts themselves are dangerous and capable of causing harm. Because they feel responsible for the danger, they also feel responsible for eliminating it (Salkovskis, 1989). A number of studies have confirmed that people who have beliefs of excessive responsibility feel more discomfort than others when they have intrusive thoughts (Freeston, 1992).

Dysfunctional beliefs about control of thoughts

Freeston et al (1992) also found that people with OCD tend to have maladaptive ideas as to how thinking works. Instead of regarding intrusive thoughts as meaningless, they tend to believe that they should (and can) control unwanted and unpleasant thoughts. Lack of control, they believe, will lead to them to lose control of their behaviour and “go crazy” (Clarke & Purdon, 1993).

Evaluation of the cognitive-behavioural view

Evidence has been obtained that frequent intrusive thoughts are a normal aspect of human cognition; for example, Rachman & deSilva (1978) found that 84% of normal participants reported unwanted and repetitive intrusive thoughts.

Further research has confirmed that OCD sufferers resort to more elaborate neutralising strategies than others, and that they do, at least temporarily, reduce the anxiety they feel (Roper et al, 1973). They also experience a greater frequency of intrusive thoughts than normal controls.

Despite the strong evidence outlined above it is unclear whether the attempts at neutralising the negative thoughts are as important in the development of the disorder as some theorists claim (e.g., Salkovskis, 1989). Clarke & Purdon (1993), for example, suggest that the inability to dismiss such thoughts, and the idea that the thoughts need to be controlled, are far more important.