In The Boy Who Couldn't Stop Washing: The Experience & Treatment of Obsessive-Compulsive Disorder (1989), Judith L. Rapoport writes: "When patients start before adolescence, they often count, check, or repeat movements. In adolescence, they wash. After adolescence, they may ruminate. But at some state, almost 85 percent of our patients have some grooming or washing ritual." Rapoport poses an intriguing question. "Is there some vestigial center in the brain for grooming behaviors that is activated in this disease?"
When primates groom, they form attachments:
In The Thinking Ape: Evolutionary Origins of Intelligence (1995), Richard Byrne writes, "In the world of monkeys and apes, time and effort invested in grooming form the bonds we would call friendship. Animals that groom together are more likely to share food and answer one another's distress call. Food is more readily shared with groomers and a groomer's distress call is more likely to be answered."
Robin Dunbar, in Grooming, Gossip, and the Evolution of Language (1996), also discusses grooming in the context of important relationships—including the mother-child relationship. "These alliances," Dunbar writes, "are established and maintained by grooming, the most social activity in which monkeys and apes engage. In some species, as much as a fifth of the entire day may be spent grooming, or being groomed by, other group members. A mother will spend hours devotedly grooming her offspring, carefully leafing through its fur in search of dead skin, matted hair, bits of leaf and burrs that have become entangled in its hair as the animal brushes it way through the vegetation during the day's foraging. She will also groom her friends and relations, in what seems to be selfless devotion to their hygienic interests. Keeping the fur clean and the skin healthy is obviously an important factor in the life of any animal."
In Introduction to Animal Behaviour (1998), Aubrey Manning and Marian Stamp Dawkins write: "… Seyfarth (1984) was able to show that frequent grooming between certain members of a vervet monkey group set up relationships such that one monkey was more likely to call upon another to aid it in a conflict situation, and was more likely to be sucessful if it did so. It is also very common to find that a mother and her offspring, particularly her daughters, form the most enduring of mutual support groups within the overall social structure."
Like it or not, we humans are primates. In their 2006 article in Time magazine, "What Makes Us Different," Michael Lemonick and Andrea Dorfman sum things up nicely. "Scientists figured out decades ago that chimps are our nearest evolutionary cousins, roughly 98% to 99% identical to humans at the genetic level. When it comes to DNA, a human is closer to a chimp than a mouse is to a rat."
Our primate relatives include chimpanzees and bonobos; animals in the monkey family including rhesus monkeys, baboons, and macaques; and prosimians, a name meaning pre-monkey, including lemurs and bush babies. Take note of what the three lemurs, pictured below, are doing. We look all the way back to our prosimian ancestors to understand the vast depth of evolutionary time in which innate patterns of behavior such as grooming have existed.
In "For the love of lemurs," The Smithsonian, April 2006, Richard Conniff explains that "grooming is so important to lemurs that it has shaped the evolution of their teeth." In humans, the "lower canines and incisors stand upright, for biting and tearing." In lemurs, Conniff points out that these teeth protrude outward, forming a "fine-toothed comb plate" for raking through one another's hair to remove bits of dead skin and insects.
Conniff interviewed Patricia Wright, a primatologist who works on the small island now called Madagascar. Wright names the lemurs she studies. One such lemur, Pale Male, mated with a female called Sky Blue Yellow, producing a son, Purple Haze. One night, Sky Blue Yellow was lost to a predator. Pale Male, badly battered, soon also disappeared, leaving behind two-year-old Purple Haze. Pale Male returned six months later with a new female, to the absolute delight of Purple Haze. As Wright recalls the reunion in Conniff's article, "That baby was so excited to see that father, and that father was so excited, and they just groomed and groomed and groomed."
Grooming, exaptation, and human compulsions:
Especially for primates, grooming has become more than just a fixed-action pattern. Grooming bioprograms probably evolved for keeping the skin healthy and then subsequently evolved into a form of social interaction necessary for friendship and group bonding. This bonding together in groups promotes survival. This is not to say that the social attachments that grooming facilitates are found only in primate communities. My dogs groom each other and wolves probably also groom each other, thus fortifying bonds within the pack.
Michael Shermer discusses exaptation in Why Darwin Matters: The Case Against Intelligent Design. Exaptation occurs when "a feature that originally evolved for one purpose is coopted for a different purpose." Although it is a bit off topic, it is interesting to note that, other than the title of his book, Shermer does not always fall so hard on one side of the fence. The following are two excerpts from his book:
As we are pattern-seeking, story-telling primates, to most of us the pattern of life and the universe indicates design. For countless millennia we have taken these patterns and constructed stories about how life and the cosmos were designed specifically for us from above. For the past few centuries, however, science has presented us with a viable alternative in which the design comes from below through the direction of built-in self-organizing principles of emergence and complexity. Perhaps this natural process, like the other natural forces which we are all comfortable accepting as non-threatening to religion, was God's way of creating life. Maybe God is the laws of nature—or even nature itself—but this is a theological supposition, not a scientific one.
If religion and spirituality are supposed to generate awe and humility in the face of the creator, what could be more awesome and humbling that the deep space discovered by Hubble and the cosmologists, and the deep time discovered by Darwin and the evolutionists.
It is contended here that when humans compulsively groom, such as in trichotillomania and compulsive skin picking, sometimes called "dermatillomania," frustration over attachment issues is as much in play as frustration over any kind of sensory irritant. Could compulsive grooming serve as an atavistic way to search out attachment opportunities? The term atavistic is especially appropriate here since, in our modern human culture, we have lost the necessity to groom people with whom we have a relationship. We pay professionals instead.
When stress, especially loneliness, overstimulates the VIGILANCE-SEEKING system in humans, It is thought that the system can still activate ancient bioprograms, even when the only target for such behavior is the self. Health professionals often call grooming compulsions self-directed behaviors. It is accepted that grooming behavior often serves as displacement behaviors in the animal world. At worst, grooming routines can become dangerous stereotypies. The image below links to a Wikipedia entry of "social grooming" that is very interesting.
In "Displacement Activities as a Behavioral Measure of Stress in Nonhuman Primates and Human Subjects" (2002) Alfonso Troisi writes:
Traditionally, research on human stress has relied mostly on physiological and psychological measures with a relatively minor emphasis on the behavioral aspects of the phenomenon. Such an approach makes it difficult to develop valid animal models of the human stress syndrome. A promising approach to the study of the behavioral correlates of stress is to analyze those behavior patterns that ethologists have named displacement activities and that, in primates, consist mostly of self-directed behaviors. In both nonhuman primates and human subjects, displacement behavior appears in situations characterized by social tension and is likely to reflect increased autonomic arousal. Pharmacological studies of nonhuman primates have shown that the frequency of occurrence of displacement behavior is increased by anxiogenic compounds [drugs that increase anxiety] and decreased by anxiolytic drugs [drugs that decrease anxiety]. Ethological studies of healthy persons and psychiatric patients during interviews have found that increased displacement behavior not only correlates with a subjective feeling state of anxiety and negative affect but also gives more veridical [truthful; accurate] information about the subject's emotional state than verbal statements and facial expression. The measurement of displacement activities may be a useful complement to the physiological and psychological studies aimed at analyzing the correlates and consequences of stress.
Grooming, patterns, antipsychotics, and mice:
Compulsive grooming often involves repeated, rigid patterns of behavior. In animals, ethologists refer to such rigid patterns as fixed-action patterns. Neuron firing patterns that produce such rigid behavior are genetically encoded in the brain. Thus they are present at birth. (See Fixed-action patterns and OCD). Stereotyped, rigid behavioral patterns are also characteristic of OCD symptoms other than grooming such as counting, punding, cleaning, and organizing one's environment according to certain rules of symmetry or category. Repetition of patterns can also be identified in many kinds of obsessions. Punding, as used here, involves repetitive handling and arranging of objects.
Perhaps in some cases of OCD, grooming bioprograms get coupled with excessive motivation to produce grooming symptoms. In other cases of OCD, perhaps excessive motivation couples with other less specific pattern generators in the brain to produce symptoms that on the surface, may seem more acceptable. A person who cannot stop cleaning their home, however, will at some point seem just as stricken as someone who pulls out hair or picks at skin. Compulsions force you to withdraw from the world around you in order to attend to symptoms. The purpose of CorticalBrain.com is to examine commonalities in brain systems and their functions, rather than simply categorizing symptoms, so as to better understand obsessions and compulsions.
On this webpage, we will discuss grooming behaviors specifically along with medication issues particularly associated with grooming behaviors. In separate webpages we will discuss the neurocircuitry of obsessions and compulsions in general and medication and treatment issues related to obsessions and compulsions. Please read the material related to medications if you are considering taking medications for treatment of any kind of obsessions, compulsions, or tics. A licensed medical doctor who maintains an interest in psychopharmacology, who stays up to date on drug research, and who listens carefully to you as you describe symptoms, is your best link to finding effective treatments.
Now we will discuss rodents. These creatures have contributed much more to the human race that most of us realize. Adrian R. Morrison, in An Odyssey with Animals: A Veterinarian's Reflections on the Animal Rights & Welfare Debate (2009), quotes Muriel Davisson, director of the Genetic Resources at the famous Jackson Laboratory in Bar Harbor, Maine. Davisson notes that "the protein coding sequence of DNA is 85 to 95% conserved between the mouse and human genome. This genomic conservation provides additional evidence of potential benefits to be gained from using mouse models of human diseases (2005)."
In "Comparison of the Effects of Antipsychotic Drugs in Two Antipsychotic Screening Assays: Swim-Induced Grooming and Apomorphin Climbing Test in Mice," authors Kedves, Sághy, and Gyertyán describe the swim-induced grooming test that is a widely used model "for screening antipsychotic drugs." This point here is that if you want to increase dopamine neurotransmission in mice (in order to later test the effectiveness of dopamine antagonists), all you have to do is put some mice in an extremely stressful situation. In short, researchers put mice in a "swimming chamber" of flowing water and force them to swim. You can imagine their stress. When you let them out, what do they do? They groom, probably more than usual, trying to assure themselves that they are out of the water, out of danger. And what will stop the grooming? Medications that block dopamine transmission.
In a study titled "Swim-Induced Grooming in Mice is Mediated by a Dopaminergic Substrate" (1981), Chesher and Jackson found that fluoxetine (the generic for Prozac) had no effect on stress-induced grooming. An older drug of a different class, haloperidol, had a strong effect at decreasing stress-induced grooming. Haloperidol has traditionally been considered an antipsychotic medication. the bold emphasis is added below
Grooming induced in mice after a period of swimming was potently and dose-dependently blocked by neuroleptics. The order of potency of the neuroleptics was spiroperidol greater than haloperidol greater than cis-flupenthixol greater than pimozide greater than chlorpromazine greater than thioridazine. The trans isomer of flupenthixol was inactive at 40 microM/kg. The alpha-adrenergic receptor antagonists, phentolamine and phenoxybenzamine, and the catecholamine synthesis inhibitor, alpha-methyl-p-tyrosine, were essentially without effect on the grooming behaviour. Amitriptyline inhibited grooming behaviour only in doses which severely affected the animals' motor function. Fluoxetine was without effect. Cis-flupenthixol was less active in inhibiting grooming in animals chronically treated with haloperidol than in control animals, indicating the presence of supersensitive dopamine receptors. The data indicate that swim-induced grooming in mice is mediated via dopaminergic systems.
Please note that a caution regarding the use of thioridazine is included in a separate CorticalBrain.com webpage, in a section titled Medication caution—thioridazine. If you take this link, click on the BACK button of your browser to return to this page.
In "Super-Stereotypy I: Enhancement of a Complex Movement Sequence by Systemic Dopamine D1 Agonists" (2000) Berridge et al. found that when they administered to rats certain chemicals that activated a certain class of dopamine receptors—namely, D1 receptors—the rats would perform grooming routines more frequently and more often to completion. They write: "Thus, dopamine D1 receptor activation appears to contribute to a kind of sequential super-stereotypy in which a complex, stereotyped behavioral sequence is initiated more frequently and more often goes to completion." When the researchers activated D2 receptors, overall grooming and completion of grooming routines was reduced. So it is not necessarily dopamine transmission in general that is associated with grooming compulsions. However, Denys, Zohar, and Westenberg, in "The Role of Dopamine in Obsessive-Compulsive Disorder: Preclinical and Clinical Evidence, point out that in an animal model "in which rats are chronically treated with the selective D2/3 receptor agonist quinpirole, a ritual-like set of behavioral acts resembling OCD checking behavior was observed." An "agonist" in this case is a drug that binds to and activates a receptor, much in the same way as an endogenous dopamine molecule might bind to and activate the receptor.
In "Super-Stereotypy II: Enhancement of a Complex Movement Sequence by Intraventricular Dopamine D1 Agonists" (2000), Berridge and Aldridge explain: "The full D1 agonist, SKF 82958, also increased the likelihood that the pattern would be completed, thus causing sequential super-stereotypy in the strongest sense. Our results highlight a role for dopamine D1 receptors, probably within the basal ganglia, in the production of sequential super-stereotypy of complex behavioral patterns."
It may not always be, however, that dopamine is the only player in producing obsessions and compulsions. Duke molecular geneticist Guoping Feng has led an international team of researchers in finding a link between synaptic communication in the corpus striata complex and grooming compulsions. The link provided here will take you back to an anatomical discussion of the corpus striata complex in Part 1 of CorticalBrain.com. We will discuss the role of the corpus striata complex in generating obsessions and compulsions later in this Part 3 narrative.
One of the mice in the Feng team's study is pictured to the right (links to source). An article in Science Daily (2007) explains that researchers found that mutant mice "born without a key brain protein compulsively groom their faces until they bleed and are afraid to venture out of the corner of their cages. When given a replacement dose of the protein in a specific region of the brain, or the drugs used to treat humans suffering from obsessive-compulsive disorder (OCD), many of these mice seem to get better." The drugs used in this study were selective serotonin reuptake inhibitors (SSRIs). Science Daily reports: "While SSRIs are the most commonly prescribed drug for humans with OCD, they are only effective for about half the patients, suggesting to Feng that many pathways involving different neurotransmitters are likely involved."
Studies such as the one Feng headed do not necessarily indicate that people with grooming compulsions have a gene mutation. What it does show, however, is that dysfunction in either the serotonin or the dopamine neurotransmitter systems can produce compulsive grooming. In the study described below, it is increased dopamine transmission in the corpus striata complex, also called the basal ganglia, that probably drives grooming compulsions.
BMC Biology provides full internet access to Berridge et al., "Sequential Super-Stereotypy of an Instinctive Fixed Action Pattern in Hyper-Dopaminergic Mutant Mice: A Model of Obsessive Compulsive Disorder and Tourette's" (2005). Excerpts from the article—that pertain to OCD, including grooming compulsions, and/or Tourette syndrome—follow. This article's presentation and internet access is outstanding. The authors clearly illustrate the patterns involved in grooming behaviors. See the illustration below taken from the on-line article. The internet version of the article includes links to video footage of the mice grooming. For easier viewing of the figures, access the PDF version of the file. It is important to remember that the genetically altered mutant mice referenced in the title of the article above had 170% more dopamine in parts of the corpus striata complex (specifically, the "neostriatum") that average wild mice do.
Berridge et al write:
Background: Excessive sequential stereotypy of behavioral patterns (sequential super-stereotypy) in Tourette's syndrome and obsessive compulsive disorder (OCD) is thought to involve dysfunction in nigrostriatal dopamine systems. In sequential super-stereotypy, patients become trapped in overly rigid sequential patterns of action, language, or thought. Some instinctive behavioral patterns of animals, such as the syntactic grooming chain pattern of rodents, have sufficiently complex and stereotyped serial structure to detect potential production of overly-rigid sequential patterns. A syntactic grooming chain is a fixed action pattern that serially links up to 25 grooming movements into 4 predictable phases that follow 1 syntactic rule. New mutant mouse models allow gene-based manipulation of brain function relevant to sequential patterns, but no current animal model of spontaneous OCD-like behaviors has so far been reported to exhibit sequential super-stereotypy in the sense of a whole complex serial pattern that becomes stronger and excessively rigid. Here we used a hyper-dopaminergic mutant mouse to examine whether an OCD-like behavioral sequence in animals shows sequential super-stereotypy. Knockdown mutation of the dopamine transporter gene (DAT) causes extracellular dopamine levels in the neostriatum of these adult mutant mice to rise to 170% of wild-type control levels.
Results: We found that the serial pattern of this instinctive behavioral sequence becomes strengthened as an entire entity in hyper-dopaminergic mutants, and more resistant to interruption. Hyper-dopaminergic mutant mice have stronger and more rigid syntactic grooming chain patterns than wild-type control mice. Mutants showed sequential super-stereotypy in the sense of having more stereotyped and predictable syntactic grooming sequences, and were also more likely to resist disruption of the pattern en route, by returning after a disruption to complete the pattern from the appropriate point in the sequence. By contrast, wild-type mice exhibited weaker forms of the fixed action pattern, and often failed to complete the full sequence.
Conclusions: Sequential super-stereotypy occurs in the complex fixed action patterns of hyper-dopaminergic mutant mice. Elucidation of the basis for sequential super-stereotypy of instinctive behavior in DAT knockdown mutant mice may offer insights into neural mechanisms of overly-rigid sequences of action or thought in human patients with disorders such as Tourette's or OCD.
Next-> Innate Behavior Grooming OCD and Tourette Syndrome - Barber mice and trichotillomania
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