Biology 202, Spring 2005
Second Web Papers
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TTM is considered to be an Obsessive Compulsive Disorder (OCD) spectrum disorder (2). Obsessions are repetitive, often unwanted thoughts, and compulsions are repeated actions used to cure anxiety and other responses caused by the obsessions (2). For example, a particular OCD sufferer might be obsessed with thinking that she left the stove on, and will compulsively check to see if the stove is on in order to resolve the worry. TTM is in the OCD spectrum rather than being an actual OCD because the "obsessive" component is often not present. Certain types of hair pulling rituals do have an obsessive component, and some clinicians consider there disorders as separate from TTM, while others refer to them as variations within TTM. In the hair pulling variation that is considered to be an OCD, the individual thinks that there are certain hairs which are different or bad (1). This is often because the hair is more coarse or curly than the others, and the individual becomes absorbed in thinking about the unique hair and is not satisfied until it is found and removed. In Body Dysmorphic Disorder, the person becomes convinced that some area of their body is abnormal or unsightly, and when this pertains to hair, the person will compulsively try to remove this area of hair. This is similar to Perfectionism, where the person feels that their hair not as it should be, and so will obsessively pull it out. There have been cases where individuals pluck their eyebrows and eyelashes excessively and end up without hair in these areas (1).

The Habit Disorder form of TTM is where the sufferer feels compelled to pull her hair, often in times of stress (1). This can be either conscious or unconscious, but the patient is usually aware that the behavior is irrational. Many researchers believe that the compulsion happens because TTM is a learned behavior. The person responds to anxiety or discomfort by pulling at the hair and then feels comforted. Since hair pulling brings the reward of relaxation, the behavior is repeated (3). The pathway to pulling that is created is a result of processes in the nervous system. In the nervous system, there are nerve cells (neurons) which have the ability to fire when they are stimulated up to a certain point, and this is known as the creation of an action potential. The signal is transmitted from the axon of the first neuron, which is an outgrowth of the neuron that is sending the signal, to a dendrite of the second neuron, which is an outgrowth that receives signals. The first neuron will send a signal to another neuron, creating a neural pathway. Learning theories have shown when pathways are repeated, it becomes easier to use that pathway. This is summarized in Hebb's Principle (1949), which states that "Whenever an axon of cell A is near enough to excite a cell B and repeatedly or persistently takes part in firing it, some growth process or metabolic change takes place in one or both cells such that A's efficiency as one of the cells firing B is increased (4)."

Individuals will also pull when the person's activity level is low, such as while reading or watching television (1). Research has shown that when brain activity is low, levels of the neurotransmitter serotonin are also low (5). A neurotransmitter is a chemical that is released by one neuron and transmitted to another neuron or receptor. At times when serotonin levels are low, the brain is working in a partly unconscious state, and so the hair pulling provides a self-stimulation.

The idea that a decrease in serotonin levels can be a trigger for hair pulling leads to the often prescribed type of medication for this disorder, Selective Serotonin Reuptake Inhibitors (SSRIs). Between the two neurons that are participating in a signaling pathway, there is a space called the synapse. The neurotransmitter leaves from the presynaptic terminal and is taken up at the postsynaptic terminal. Serotonin is transmitted to the postsynaptic terminal, to be taken up again by the presynaptic cell. This reuptake can be a problem because serotonin does not stay in the synapse long enough to be recognized by the recipient neuron (6). This will cause there to be low levels of serotonin in the system. SSRIs block the reuptake of serotonin, thereby increasing serotonin levels in the body, which can in turn increase stimulation during low activity times. SSRIs are used to treat TTM, but there are no definitive answers as to why it works. Although the theory about increasing stimulation in times of low activity is feasible, it is important to note that SSRIs are antidepressants. Since hair pulling is often correlated with an increase in stress, it might just be that SSRIs make people feel better so the trigger for hair pulling is taken away (3).

The hair pulling aspect of TTM is not necessarily the most important part of the ritual for many people. The "grooming" aspect can provide a soothing effect, where the individual receives pleasure from hair stroking, twisting, tweaking, etc (1). The idea that grooming oneself or others can be a positive experience is nothing new, of course, since humans and other animals often partake in this. In mice, grooming has been linked to a certain gene by researchers at the University of Utah, whose results were revealed in 2002. They found that by eliminating the homeobox-containing (Hox) gene Hoxb8, the mice were more prone to pulling out their own hair and the hair of neighboring mice (7). They believe that the Hoxb8 regulates hair pulling in mice, and this could also give explanations for TTM in humans with further research. Other evidence that this disorder has a biological basis is that in twin-studies, 95% of twins both suffer from TTM. It also seems to run in families.

It could be that TTM is genetic in the realm of developing it, but the conditioning is a learned behavior. In my experience, the first time I noticed that there are certain hairs which are curlier than others, I remember thinking, "It is fun to play with these hairs, and I should do it more often." At that time, it was more of a conscious game, but by repeating the behavior, it became a habit. The behavior therapy treatment for this disorder tries to first make the patient aware of what triggers the hair pulling and then try other behaviors to take the place of or to counteract hair pulling (3). Awareness often helps the person to know they are doing it, but attempting to unlearn the behavior is often ineffective. One reason for this might be that the alternative behaviors such as sitting on your hands or squeezing a ball do not give the pleasure that the patient's body has correlated with hair pulling. Because of this, training oneself to perform a new behavior is really just an exercise in obtaining the willpower to stop. Another idea is to put a rubber band on your wrist and flick yourself with it every time you attempt to pull you hair. Having tried this recently, I find myself faced with the decision to either hurt myself or do something that I find pleasurable, and I simply don't have the desire to cause myself the immediate pain brought on by the rubber band.

Although many Americans are thought to suffer from TTM, intense research has only begun fairly recently because the disorder was previously considered to be rare (8). This is in part due to the shame that many people experience and the elaborate mechanisms used to hide the problem instead of seeking help (1). Although the reasons for pulling and methods of pulling are unique to each individual, it is important to note that many people suffer from a variety of methods. This can make curing the disorder even more difficult, since the therapies might only work on certain triggers and responses, even though the individual is afflicted by a variety of complications.

References

1) Hair Pulling, a.k.a., Trichotillomania, Useful website for variations and causes of the disorder

2) Obsessive Compulsive Disorder, Website about OCD and the OCD spectrum

3) Trichotillomania, Information about behavior therapy and the learning theory

4) Synaptic Plasticity, Resource for Hebb's Principle of associated learning

5) FAMILY: Are we producing a generation of hyperactive zombies?, Article which discusses the affects of serotonin on levels of stimulation

6) Selective Serotonin Reuptake Inhibitors, Article that explains the structure and functions of SSRIs

7) Gene Prevents Excessive "Grooming" (at least in mice), Article on gene testing for hair pulling in mice

8) What is Trichotillomania?, Resource on a hair pulling study


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