Categories
Health and Disease

Cochlear Implants: A Success Story For Auditory Prosthesis

Introduction

A cochlear implant is an electronic device that is surgically implanted to treat patients that are profoundly deaf. The first cochlear implant devices, invented by William House and John Doyle, were given to patients in 1961 (Turkington). Despite mixed results, the devices were the first successful auditory prosthesis, and they presented an interesting possibility: the ability to restore the human sense of hearing through electrical stimulation. Now, though modern cochlear implant devices have evolved from those first used in 1961, that possibility has turned into a reality. With technological advancements, cochlear implants have resulted in more viable hearing for patients. According to the National Institute on Deafness and Other Communication Disorders, 96,000 people in the US and 324,200 people worldwide have received cochlear implants as of 2017 (Turkington).

A cochlear implant is a viable option for patients who have sensorineural hearing loss—hearing loss due to damage to the sensory hair cells in a part of the inner ear called the cochlea. Movement of hair cells stimulates nerve cells (ganglion cells), which carry an electrical current to the auditory nerve that, in turn, sends the signals to the brain. In sensorineural hearing loss, however, sounds do not make it to the auditory nerve or to the brain, where the electrical signals are interpreted as sound, due to damaged hair cells. Cochlear implants combat this issue, and, while they cannot fully restore hearing, they allow patients to sufficiently hear and understand speech (Turkington).

How do cochlear implants work?

Figure: Diagram showing the external and internal parts of a cochlear implant (Diagram of Cochlear Implant).

A cochlear implant contains external parts (worn on the outside of the ear) and internal parts, which are surgically implanted in the patient, underneath the skin. The external parts (a microphone, speech processor, and transmitter) are responsible for collecting and sending sounds to the internal parts. The microphone receives sound from the environment, which is converted into a digital signal by the speech processor; this signal includes information about the sound received, such as pitch, loudness, and timing. The digital signals are converted into FM radio signals and sent to the internal parts of the cochlear implant by the transmitter (Turkington).

The signals reach the internal parts, which are implanted through an outpatient procedure for adult and adolescent patients and a one-night stay at the hospital for children. The area behind a patient’s ear is first shaved or the hair is sterilized. An incision is then made that opens the mastoid bone, allowing a device called the receiver-simulator to be placed in a depression in the bone before being sutured (stitched). The receiver-simulator receives the FM radio signals sent by the transmitter and converts them to electrical signals. The next step in the surgical procedure is threading the electrodes through the cochlea so that electrodes are positioned closely to the ganglion cells. The receiver-simulator and the electrodes that are in the cochlea are connected by a wire. These electrodes take on the job of stimulating the ganglion cells that transmit signals to the auditory nerve, which hair cells are normally responsible for. This increased nervous response to sound allows the electrical signal to reach the brain (Turkington). The resulting sounds from the implant are more artificial and mechanical than natural sounds, but they allow for improved sound detection and speech understanding.

Benefits

The results of cochlear implants vary, but the most optimal result is a near normal ability to understand speech. They improve a patient’s ability to talk on the phone, lip-read, watch TV with facial cues, and listen to music. They also help differentiate between the type and volume of sounds; patients may better perceive loud, medium, and soft sounds, such as the slamming of doors, ringing of phones, or rustling of leaves. Additionally, cochlear implants can improve a patient’s speech by regulating it so that it is easier to understand (Turkington). 

Risks

Cochlear implants have risks associated with the surgical implant procedure, as surgery with general anesthesia is needed for the implant. Some of these risks are injury to the facial nerve, cerebrospinal and perilymph fluid leak, meningitis, infection, and ringing and numbness around the ear, among others. There is also the risk of the implant failing if it’s rejected by the body, which results in the need for another surgical procedure and, possibly, localized inflammation (“Benefits and Risks of Cochlear Implants”). However, the failure rates of cochlear implants are generally low; around 0.2% of patients reject the implant, and 0.5% require reimplantation (“Cochlear Implants”).

Conclusion

To those with sensorineural hearing loss, cochlear implants are a viable option that restores a sense of hearing for patients. As with any other surgical procedure, there are a number of risks, but cochlear implants are generally one of the safer procedures for medical prosthesis. They hold the potential to restore patients to near normal hearing with benefits in speech and sound reception. While they produce “mechanical” sounds and are not capable of fully restoring a patient’s hearing, cochlear implants represent the progress and potential of medical prosthesis in restoring the human body and even the human senses.

Michelle Li, Youth Medical Journal 2020

References

“Benefits and Risks of Cochlear Implants.” U.S. Food and Drug Administration, http://www.fda.gov/medical-devices/cochlear-implants/benefits-and-risks-cochlear-implants. Accessed 29 Nov. 2020.

“Cochlear Implants.” Hearing Link, http://www.hearinglink.org/your-hearing/implants/cochlear-implants/. Accessed 24 Nov. 2020.

Diagram of Cochlear Implant. Mayo Clinic, http://www.mayoclinic.org/medical-professionals/pediatrics/news/cochlear-implants-early-intervention-to-optimize-language-outcomes/mac-20452729. Accessed 29 Nov. 2020.

“Modern Cochlear Implant.” Albert and Mary Lasker Foundation, http://www.laskerfoundation.org/awards/show/modern-cochlear-implant/. Accessed 29 Nov. 2020.Turkington, Carol A., and Josephine S. Campbell. “Cochlear Implants.” The Gale Encyclopedia of Surgery and Medical Tests, edited by Deirdre S. Hiam, 4th ed., vol. 1, Gale, 2020, pp. 383-88. Gale Health and Wellness, link.gale.com/apps/doc/CX7980900121/HWRC?u=mlin_m_newtnsh&sid=HWRC&xid=90ed2e06. Accessed 29 Nov. 2020.

Turkington, Carol A., and Josephine S. Campbell. “Cochlear Implants.” The Gale Encyclopedia of Surgery and Medical Tests, edited by Deirdre S. Hiam, 4th ed., vol. 1, Gale, 2020, pp. 383-88. Gale Health and Wellness, link.gale.com/apps/doc/CX7980900121/HWRC?u=mlin_m_newtnsh&sid=HWRC&xid=90ed2e06. Accessed 29 Nov. 2020.

Categories
Biomedical Research

Placebos and The Placebo Effect in Clinical Trials

Introduction

Something as simple as giving a sugar pill or a saline injection has proven to have beneficial effects for a patient. Because while the treatment itself has no therapeutic value, the patient’s belief that they are being medically treated or their trust in the physician can improve symptoms. That improvement of symptoms is called the placebo effect. Placebos come in various forms, and while an ethical controversy is attached to the use of placebos, it can’t be ignored that they play an important part in modern clinical trials and may play a part in future treatments.

Placebos in Clinical Trials

Currently, a drug must outperform a placebo in a clinical investigation and have “substantial evidence of effectiveness” to be approved by the FDA (Katz). However, treatments were not always held to this standard. In the past, placebos were not used in clinical trials or practice, but this changed after it became suspected that some cases of improved symptoms were not because of an effective drug or treatment but because of psychological factors–later identified as the placebo effect. Thus the placebo effect began to be taken into account during clinical trials for new drugs and treatments. Having control groups with placebos is critical in determining whether results are due to the treatment’s effectiveness or the placebo effect. 

Placebos ensure that the results obtained and symptoms reported by participants are due to the drug, and not because of any demand characteristics. The awareness of receiving a drug may result in subjects falsely reporting relief from symptoms of the disease, and not because of the drugs being tested. As a result, while the experimental group receives the drug, a control group is given a placebo that looks identical but is sugar or water-based, to ensure that all results are due to the drug, improving the validity of the study. Furthermore, to avoid researcher bias, most experiments use double-blind trials, where both researchers and participants are unaware of which group receives the placebo. This is optimal, as both the patients’ report of symptoms and the researcher’s analysis is uninfluenced by the knowledge of which participants were in what group, improving the reliability and validity of the study (“Placebo”). 

However, placebos are not limited to drugs or medication, with placebo surgery showing increasing success. Because the simple act of administering anesthesia or making an incision without any further operation being done has proved to play a role in determining the efficacy of procedures and surgeries. For instance, percutaneous coronary intervention (PCI) is done to treat angina- chest pain caused by reduced blood and oxygen reaching the heart, which is often treated by placing a stent to widen arteries. A 2018 ORBITA study questioned the effectiveness of the stent itself. In the study, participants with stable angina were randomly assigned into groups that would receive either PCI or a placebo procedure (where no stent was placed). After six weeks, their heart was put under stress through rigorous exercise, to test out the hypothesis of the placebo effect. The study found that the endpoint times of exercise of participants who had received PCI were no different than those who received the placebo procedure, alluding to the idea that the improvement of symptoms and reported success of PCI may be at least partially attributed to the placebo effect (Al-Lamee).

In the study, three participants in the placebo group experienced major bleeding, and other complications occurred (Al-Lamee). This brings up controversies over placebo surgery and the use of placebos themselves in studies and practice.

Ethical Evaluation

The controversy around placebos in research is because of the ethicality of the procedure itself. Because the participants in clinical trials that receive placebos act as controls, and while they may experience the ‘placebo effect’, they are still denied a drug that may have a higher success rate. In addition, critics argue that clinical trials involving placebo surgery result in unnecessary surgeries that run the same risks as regular procedures, as a cut is still made and anesthesia may still be used (Ford-Martin). For instance, in the ORBITA trial, the three placebo-receiving patients that had major bleeding experienced those risks. However, they only received the placebo procedure and can only experience the placebo effect, instead of the benefits of a stent or other procedures (Al-Lamee). Thus, critics argue that the use of a placebo created unnecessary risks and pain, for almost no benefit.

Therefore, there are guidelines for using placebos in clinical practice, and participant consent is a major focus because failure to obtain consent undermines the trust in a physician-patient relationship, affecting all future treatments for a patient. However, when consent is obtained, the given placebo may help relieve symptoms at least temporarily in situations where there is no well-known treatment. The placebo may even be effective when the patient knows that it will be used but doesn’t know when it was given or what exactly the placebo treatment looked like. 

For instance, in a study that had an open-lid placebo treatment for chronic low back pain, participants in the study were told they were receiving the placebo medication and made aware of its lack of active ingredients. Part of the group then continued the usual treatment for chronic low back pain, while another group also took the placebo medication as well as usual treatment. Participants reported their pain intensity by rating their pain levels on a scale of 0-10, in addition to rating difficulties in completing daily activities. At the end of the study, participants who had received the placebo reported a 30% reduction in usual pain levels despite being aware of the placebo and its effect, or lack thereof (Carvalho). While it may not be true for every case or condition, the placebo effect may still work even when patients are aware of its presence.

Conclusion

For all its controversies and debates on effectiveness, the placebo has shown to have a significant impact on treating patients for various conditions. A systematic review focusing on the effectiveness of placebo treatments for migraine prophylaxis showed 58% responded positively to sham surgery, and 22% responded positively to oral placebo medicine. Those that responded positively to the placebo treatments experienced a reduction in migraine frequency of at least 50% (Meissner).

The use of placebos has helped determine the efficacy of medications and procedures during clinical trials. The positive effects shown by placebos provide hope that the phenomenon known as the placebo effect can be developed into a viable form of treatment in the future. Therefore, despite our limited understanding of the phenomenon and the constant debate on its ethicality, the effectiveness of placebos cannot be questioned; and its use in clinical trials ensures that all drugs, procedures, and treatments are fully understood, before being introduced to the public.

Michelle Li, Youth Medical Journal 2020

References

Al-Lamee, Rasha et al. “Percutaneous coronary intervention in stable angina (ORBITA): a double-blind, randomised controlled trial.” Lancet (London, England) vol. 391,10115 (2018): 31-40. DOI:10.1016/S0140-6736(17)32714-9

Carvalho, Cláudia et al. “Open-label placebo treatment in chronic low back pain: a randomized controlled trial.” PAIN vol. 157,12 (2016): 2766-2772. DOI: 10.1097/j.pain.0000000000000700

Ford-Martin, Paula, et al. “Placebo Effect.” The Gale Encyclopedia of Alternative Medicine, edited by Deirdre S. Hiam, 5th ed., vol. 4, Gale, 2020, pp. 2101-03. Gale Health and Wellness, link.gale.com/apps/doc/CX7947800689/HWRC?u=mlin_m_newtnsh&sid=HWRC&xid=8c95ff85. Accessed 31 Oct. 2020.

Katz, Russell. “FDA: evidentiary standards for drug development and approval.” NeuroRx : the journal of the American Society for Experimental NeuroTherapeutics vol. 1,3 (2004): 307-16. DOI:10.1602/neurorx.1.3.307

Meissner, Karin et al. “Differential effectiveness of placebo treatments: a systematic review of migraine prophylaxis.” JAMA internal medicine vol. 173,21 (2013): 1941-51. DOI:10.1001/jamainternmed.2013.10391

“Placebo.” The Gale Encyclopedia of Science, edited by K. Lee Lerner and Brenda Wilmoth Lerner, 5th ed., Gale, 2014. Gale in Context: Science, link.gale.com/apps/doc/CV2644031732/SCIC?u=mlin_m_newtnsh&sid=SCIC&xid=571744c6. Accessed 31 Oct. 2020.

“Placebo Effect.” The Gale Encyclopedia of Psychology, edited by Jacqueline L. Longe, 3rd ed., vol. 2, Gale, 2016, p. 895. Gale in Context: Science, link.gale.com/apps/doc/CX3631000593/SCIC?u=mlin_m_newtnsh&sid=SCIC&xid=e0f33bb6. Accessed 31 Oct. 2020.”Use of Placebo in Clinical Practice.” American Medical Association, http://www.ama-assn.org/delivering-care/ethics/use-placebo-clinical-practice. Accessed 31 Oct. 2020.

Categories
Health and Disease

Obsessive-Compulsive Disorder (OCD): More Than Being Obsessively Neat and Tidy

Abstract

Obsessive-Compulsive Disorder (OCD) is the fourth most common psychiatric illness (Fitzgerald). According to the Anxiety and Depression Association of America, 1 in 40 adults and 1 in 100 children in the U.S. are affected by OCD. OCD is a two-part mental disorder beginning with an obsession over certain thoughts and leading to the repetition of certain actions in a continuous cycle that impairs daily life. The process begins with obsessive thoughts (obsessions) that cause anxiety and lead to the individual repeating a behavior (compulsions). This could look like visualizing the spread of germs contaminating one’s hands, leading to excessive hand washing. Following through with compulsions only grants temporary relief from anxiety before the individual encounters another OCD trigger. However, if the individual does not follow through with the compulsion, it could result in anxiety and panic attacks. Both the obsessions and compulsions are involuntary. 

Types of OCD

OCD has many faces, and while every case is different, a person’s OCD commonly falls into one of these five categories.

  1. Checking

Checking is when someone with OCD “makes sure” of something, whether that’s if they left the stove on, if they turned off the bathroom lights, if they locked the front door, etc. It’s accompanied by fears of a dreadful event, such as the person’s home burning down or the death of someone close to them or even themselves (“Types of OCD”). The anxiety disorder side of OCD is what fuels this fear. The individual must check if they forgot their wallet; otherwise, their two-year old niece will be diagnosed with an incurable disease. These thought processes and the resulting compulsions—in this case, checking for a wallet—commonly impede the person’s daily life. It can result in someone being unable to leave their house until they check (and then check again), causing delays in a person’s day that they cannot do anything about.

  1. Contamination / Mental Contamination

The obsessions of someone with contamination related OCD is tied to a fear of harm to themselves or a loved one. It is also associated with a fear of germs and dirt. People with contamination OCD often avoid objects, places, or other people in fear of contamination through germs, dirt, etc. They may avoid public spaces, door knobs, shaking hands, among other things. Compulsions may be repeatedly washing hands until they’re raw, brushing teeth, showering, or laundering clothes immediately after returning home. They follow through with these compulsions to ensure that they don’t become ill or cause others to become ill (“Types of OCD”).

In addition, there is also a mental side to contamination related OCD. It is similar to physical contamination with the exception that people with this subtype of OCD perceive the contamination as happening internally, inside their body. They also feel the urge to clean out the contaminants, which in this case are negative thoughts or things they’ve heard, instead of the usual germs or debris. Similar to contamination OCD, they do this by showering and washing (“Types of OCD”). The key difference between contamination and mental contamination OCD is the presence of a physical object versus a human. The source of germs and dirt in contamination OCD is a physical object. However, the “germs and dirt” of mental contamination OCD—aka the negative things they’ve heard—originates from another human.

  1. Hoarding

Hoarding is not unique to OCD; it can be a mental disorder on its own or a symptom of another mental illness such as OCD or OCPD (“Hoarding: The Basics”). Hoarding is when someone is unwilling to discard certain possessions and, instead, feels the need to save them, resulting in an excessive accumulation of clutter that impairs their daily life. That need to save possessions can be for a number of reasons, and, in some cases, is linked to OCD and anxiety. For instance, some people with hoarding OCD believe that items that touch the floor are contaminated; therefore, no one should touch these items else they also become contaminated (“OCD Symptoms: OCD-Related Hoarding”). These obsessive thoughts are similar to those of someone with contamination related OCD. This thought process renders the person physically and mentally unable to dispose of the item, leading to excessive accumulation as the cycle continues.

  1. Rumination and Intrusive Thoughts

Both rumination and intrusive thoughts in OCD revolve around certain thoughts in an individual’s head. In the context of OCD, rumination is when an individual spends an excessive amount of time focusing on a question or thought. They can be focusing on a religious or philosophical topic such as life and death. However, they don’t arrive at a conclusion that satisfies them, leaving them to ponder for excessive amounts of time (“Types of OCD”).

For someone with OCD, intrusive thoughts are when disturbing thoughts reappear over and over in an individual’s mind. These thoughts are involuntary, and someone with OCD may begin believing these thoughts. Anxiety stems from the fear that they may act on the repugnant thoughts or impulses. These thoughts may be related to violence, sexual harm, relationships, etc. An example of an intrusive thought would be obsessing over the thought of harming other people with kitchen knives or other sharp objects, and the compulsion would be locking away those objects so as not to harm anyone (“Types of OCD”). The individual may question why they are having these thoughts or be consumed by the thought that they have already performed the violent action (even though they haven’t).

  1. Symmetry

People with symmetry-related OCD feel uncomfortable when objects are not aligned symmetrically or if an action isn’t done symmetrically. They become fixated on the positions of objects—such as books or clothes—and cannot move on until those objects are arranged in the “right” way (“Types of OCD”). People with OCD can also feel this way about certain actions; they have to perform an action on both sides or any number of sides to maintain balance and symmetry. For example, if someone with symmetry-related OCD scratches the left side of their face, they must scratch the right side to avoid a feeling of discomfort (Fitzgerald). This can be tied to a fear of harm to the person themself or someone close to them, but it can also just be to avoid the unease that they experience before satisfying a compulsion.

Causes

Symptoms of OCD commonly begin to appear in the pre-adolescent and early adulthood stages of life. The most common age range in which people start to experience the symptoms of OCD is between the ages of 10 and 24, but OCD can start at any age (Fitzgerald). The causes behind OCD are not crystal clear, but they may be linked to biological, genetic, and environmental factors. 

Cases of OCD have been linked to family in many ways. For instance, immediate family members of a person with OCD have a 25% chance of also developing the disorder (Ford-Martin). This means that the parents, siblings, and children of someone with OCD have increased chances of also having OCD, hinting that the disorder is somehow connected to family lines. This pattern may be a result of learning from and watching the behaviors of a family member with OCD (“Obsessive-compulsive disorder (OCD)” [NCH Healthcare System]). Part of the answer may also lie in genetics. Some twin studies have revealed that identical twins—twins that come from the same egg and therefore share all of their genes—are more likely to both develop OCD than fraternal twins. Genetics is not the only determiner though, as the rate for both identical twins exhibiting OCD is not 100% (Fitzgerald)

Some suggest that abnormal brain activity that differs from those without a mental illness or disorder may also be responsible for the obsessions and compulsions of OCD. Researchers have found that the orbital cortex of the brain is hyperactive in people with OCD, which may be responsible for the feelings of “alarm” that push people toward fulfilling compulsions (Ford-Martin). Abnormally low levels of serotonin in the brain may also play a role in OCD, as serotonin aids in communication between the frontal lobe and other parts of the brain that are connected to OCD compulsions (Ford-Martin).

Diagnosis

OCD can only be diagnosed by a mental health professional such as a psychiatrist or psychologist. It is usually done through an interview-like process in which a series of questions are asked to identify if the core aspects of OCD are present and therefore warrants a diagnosis. Examples of questions that a professional may ask are if the patient frequently cleans, if the patient checks things a lot, if the patient is bothered by thoughts they can’t rid themselves of, etc. Professionals take into account the effect of the symptoms on the patient’s life, whether the symptoms are time-consuming (taking up more than an hour each day), cause distress, impede function in daily life, etc. (“Diagnosing OCD”). One commonly used assessment is the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), which has five questions each for obsessions and compulsions; the Y-BOCS assesses the factors mentioned above (Fitzgerald).

Treatment

OCD is usually treated with cognitive-behavioral therapy (CBT) and medications.

Cognitive-behavioral therapy is a type of psychotherapy that has proven to be effective in treating certain mental illnesses. More specifically, the technique of exposure and response prevention (ERP) is the most effective in treating OCD; it helps reduce symptoms in 75%-80% of OCD patients (Fitzgerald). In ERP, the patient and therapist create a list of the patient’s obsessions and compulsions, starting with something mild and getting more extreme—these tasks look different for every patient based on their OCD. The idea is to expose the patient to OCD-triggers without having them give into compulsions. Patients start at a mild level where they will be able to tolerate not giving in to a compulsion. With each CBT session, the patient moves up the list with more difficult, OCD-inducing tasks. The tasks are repeated, and with each exposure, the anxiety associated with an obsession is reduced until the patient finds it manageable. One example of ERP is if a patient with contamination OCD is tasked with touching contaminated objects with increasing time between when they make contact and when they’re allowed to wash their hands (or give in to their compulsion).

OCD can also be treated by medication that increases levels of serotonin (selective serotonin reuptake inhibitors or SSRIs). These are fluoxetine, fluvoxamine, paroxetine, sertraline, citalopram, and escitalopram. Clomipramine and venlafaxine are antidepressants that may also be prescribed for OCD patients; risperidone and haloperidol are antipsychotics that are an option for severe cases of OCD (Ford-Martin).

The last resort for OCD patients that don’t respond to CBT or medication is brain surgery. The operation removes a part of the brain called the “cingulate cortex” (Ford-Martin). The surgery is beneficial to 30% of OCD patients who receive it, resulting in lessened symptoms (Fitzgerald).

Conclusion

Obsessive-Compulsive Disorder is a mental disorder that significantly interferes with the daily lives of sufferers through a series of obsessions and compulsions; it is much more than the media’s portrayal of OCD being obsessively neat or tidy. OCD can look different for every patient, and the exact cause of the disorder hasn’t been determined. However, treatment through CBT and medication can help lessen symptoms, and it is important that people with OCD are not misunderstood and seek the professional help they need.

Michelle Li, Youth Medical Journal 2020

References

“Diagnosing OCD.” OCD-UK, http://www.ocduk.org/ocd/diagnosing-ocd/. Accessed 28 Sept. 2020.

Fitzgerald, Jane A., et al. “Obsessive-compulsive and Related Disorders.” The Gale Encyclopedia of Mental Health, edited by Brigham Narins, 4th ed., vol. 3, Gale, 2019, pp. 1149-56. Gale Health and Wellness, link.gale.com/apps/doc/CX2491200351/HWRC?u=mlin_m_newtnsh&sid=HWRC&xid=5cfaa5d0. Accessed 28 Sept. 2020.

Ford-Martin, Paula, and Lisa C. DeShantz-Cook. “Obsessive–Compulsive Disorder.” The Gale Encyclopedia of Alternative Medicine, edited by Deirdre S. Hiam, 5th ed., vol. 4, Gale, 2020, pp. 1942-45. Gale Health and Wellness, link.gale.com/apps/doc/CX7947800639/HWRC?u=mlin_m_newtnsh&sid=HWRC&xid=492d0698. Accessed 28 Sept. 2020.

“Hoarding: The Basics.” Anxiety and Depression Association of America, ADAA, adaa.org/understanding-anxiety/obsessive-compulsive-disorder-ocd/hoarding-basics. Accessed 23 Sept. 2020.

“Obsessive Compulsive Disorder.” Georgia Behavioral Health Professionals, http://www.mygbhp.com/condition/obsessive-compulsive-disorder/. Accessed 28 Sept. 2020.

“Obsessive-compulsive Disorder.” National Alliance on Mental Illness, http://www.nami.org/About-Mental-Illness/Mental-Health-Conditions/Obsessive-compulsive-Disorder. Accessed 28 Sept. 2020.

“Obsessive-Compulsive Disorder.” National Institute of Mental Health, http://www.nimh.nih.gov/health/topics/obsessive-compulsive-disorder-ocd/index.shtml. Accessed 28 Sept. 2020.

“Obsessive-Compulsive Disorder (OCD).” Anxiety and Depression Association of America, ADAA, adaa.org/understanding-anxiety/obsessive-compulsive-disorder-ocd. Accessed 24 Sept. 2020.

“Obsessive-compulsive disorder (OCD).” NCH Healthcare System, http://www.nchmd.org/education/mayo-health-library/details/CON-20199571. Accessed 23 Sept. 2020.

“OCD Symptoms: OCD-Related Hoarding.” BeyondOCD.org, beyondocd.org/information-for-individuals/symptoms/ocd-related-hoarding. Accessed 28 Sept. 2020.

“Types of OCD.” OCD-UK, http://www.ocduk.org/ocd/types/. Accessed 27 Sept. 2020.

“What Is Obsessive-Compulsive Disorder?” American Psychiatric Association, http://www.psychiatry.org/patients-families/ocd/what-is-obsessive-compulsive-disorder. Accessed 28 Sept. 2020.