Double-Blind Clinical Trial Shows that Dose Matters with Ketamine in Depressed Patients

The results of a new clinical trial with ketamine were published in Nature’s Molecular Psychiatry journal.  Researchers conducted a double-blind, placebo-controlled, dose-ranging trial of intravenous ketamine as adjunctive therapy in treatment-resistant depression (TRD).  99 subjects, 18-70 years old with TRD (defined as having less than 50% improvement in depression symptoms with conventional therapies) were randomized into one of five arms: a single intravenous dose of ketamine 0.1 mg/kg (n = 18), a single dose of ketamine 0.2 mg/kg (n = 20), a single dose of ketamine 0.5 mg/kg (n = 22), a single dose of ketamine 1.0 mg/kg (n = 20), and a single dose of midazolam 0.045 mg/kg (active placebo) (n = 19).

The authors found that the 0.5 and 1.0 mg/kg doses of ketamine were superior to the active placebo comparator, supporting its use as a novel antidepressant therapy.  Interestingly, the lower doses that were tested did not separate from the placebo comparator.  This is study is incredibly important because previously no dose range finding studies have been conducted with ketamine in patients with TRD.  Their data suggests that clinicians who use lower doses of ketamine may not see any significant clinical response.  This is typical of most drugs and is an important step toward developing the ideal dosing regimen that balances clinical benefit and risk.

If you or someone you know is depressed, please make an appointment to see if you are a good candidate for ketamine.  Dr. Ashraf Hanna is located in Clearwater, FL and is one of the leading experts in IV ketamine therapy.  Dr. Hanna is a licensed anesthesiologist and Director of Pain Management at the Florida Spine Institute.  He has performed thousands of infusions and patients travel from all over the world to benefit from his expertise. If you want to learn more, visit his website and listen to his patient testimonies. You won’t be disappointed!  What are you waiting for?  Make an appointment today!

The National Institute of Mental Health Highlights Ketamine for Depression

The National Institute of Mental Health (NIMH) issued a highlight on ketamine for treating depression.

The most commonly used antidepressants are largely variations on a theme; they increase the supply within synapses of a class of neurotransmitters believed to play a role in depression. While these drugs relieve depression for some, there is a weeks-long delay before they take effect, and some people with “treatment-resistant” depression do not respond at all.

The delay in effectiveness has suggested to scientists that the medication-induced changes in neurotransmitters are several steps away from processes more central to the root cause of depression. One possibility for a more proximal mechanism is glutamate, the primary excitatory, or activating, neurotransmitter in the brain. Preliminary studies suggested that inhibitors of glutamate could have antidepressant-like effects, and in a seminal clinical trial, the drug ketamine—which dampens glutamate signaling—lifted depression in as little as 2 hours in people with treatment-resistant depression.34

The discovery of rapidly acting antidepressants has transformed our expectations—we now look for treatments that will work in 6 hours rather than 6 weeks. But ketamine has some disadvantages; it has to be administered intravenously, the effects are transient, and it has side effects that require careful monitoring. However, results from clinical studies have confirmed the potential of the glutamate pathway as a target for the development of new antidepressants. Continuing research with ketamine has provided information on biomarkers that could be used to predict who will respond to treatment.35 Clinical studies are also testing analogs of ketamine in an effort to develop glutamate inhibitors without ketamine’s side effects that can then be used in the clinic.36 Ketamine may also have potential for treating other mental illnesses; for example, a preliminary clinical trial reported that ketamine reduced the severity of symptoms in patients with PTSD. 37  Investigation of the role of glutamate signaling in other illnesses may provide the impetus to develop novel therapies based on this pathway.

Left: Change in the 21-item Hamilton Depression Rating Scale (HDRS) following ketamine or placebo treatment.
Right: Proportion of responders showing a 50 percent improvement on the HDRS following ketamine or placebo treatment.34

Source: Carlos Zarate, M.D., Experimental Therapeutics and Pathophysiology Branch, NIMH

One of the imperatives of clinical research going forward will be to demonstrate whether the ability of a compound to interact with a specific brain target is related to some measurable change in brain or behavioral activity that, in turn, can be associated with relief of symptoms. In a study of ketamine’s effects in patients in the depressive phase of bipolar disorder, ketamine restored pleasure-seeking behavior independent from and ahead of its other antidepressant effects. Within 40 minutes after a single infusion of ketamine, treatment-resistant depressed bipolar disorder patients experienced a reversal of a key symptom—loss of interest in pleasurable activities—which lasted up to 14 days.38 Brain scans traced the agent’s action to boosted activity in areas at the front and deep in the right hemisphere of the brain. This approach is consistent with the NIMH’s RDoC project, which calls for the study of functions—such as the ability to seek out and experience rewards—and their related brain systems that may identify subgroups of patients with common underlying dysfunctions that cut across traditional diagnostic categories.

The ketamine story shows that in some instances, a strong and repeatable clinical outcome stemming from a hypothesis about a specific molecular target (e.g., a glutamate receptor) can open up new arenas for basic research to explain the mechanisms of treatment response; basic studies can, in turn, provide data leading to improved treatments directed at that mechanism. A continuing focus on specific mechanisms will not only provide information on the potential of test compounds as depression medications, but will also help us understand which targets in the brain are worth aiming at in the quest for new therapies.

If you or someone you know is depressed, please make an appointment to see if you are a good candidate for ketamine.  Dr. Ashraf Hanna is located in Clearwater, FL and is one of the leading experts in IV ketamine therapy.  Dr. Hanna is a licensed anesthesiologist and Director of Pain Management at the Florida Spine Institute.  He has performed thousands of infusions and patients travel from all over the world to benefit from his expertise. If you want to learn more, visit his website and listen to his patient testimonies. You won’t be disappointed!  What are you waiting for?  Make an appointment today!

IV Ketamine Shows Promise in Clinical Trial with Depressed Teens

Researchers from the University of Minnesota and The Mayo Clinic found that ketamine caused an average decrease of 42% on the Children’s Depression Rating Scale(CDRS)—the most widely used rating scale in research trials for assessing the severity of depression and change in depressive symptoms among adolescents. The study recruited adolescents, 12-18 years of age, with treatment-resistant depression (TRD; failure to respond to two previous antidepressant trials). The teens were administered intravenous ketamine (0.5 mg/kg) by infusion six times over two weeks.

The study reported that the average decrease in CDRS-R was 42.5% (p = 0.0004). Five (38%) adolescents met criteria for clinical response (defined as >50% reduction in CDRS-R). Three responders showed sustained remission at 6-week follow-up; relapse occurred within 2 weeks for the other two responders. The ketamine infusions were generally well tolerated; dissociative symptoms and hemodynamic symptoms were transient. Interestingly, higher dose was a significant predictor of treatment response.

“Adolescence is a key time period for emergence of depression and represents an opportune and critical developmental window for intervention to prevent negative outcomes,” the authors wrote in the study.

“Unfortunately, about 40% of adolescents do not respond to their first intervention and only half of non-responders respond to the second treatment,” they said. “Because standard interventions require prolonged periods (e.g., weeks to months) to assess efficacy, serial treatment failures allow illness progression, which in turn worsens the outcome. Hence, novel treatment strategies to address treatment-resistant depression in adolescents are urgently needed.”

The authors concluded that their results demonstrate the potential role for ketamine in treating adolescents with TRD. Additionally, evidence suggested a dose–response relationship; future studies are needed to optimize dose.

If you or someone you know is depressed, please make an appointment to see if you are a good candidate for ketamine.  Dr. Ashraf Hanna is located in Clearwater, FL and is one of the leading experts in IV ketamine therapy.  Dr. Hanna is a licensed anesthesiologist and Director of Pain Management at the Florida Spine Institute.  He has performed thousands of infusions and patients travel from all over the world to benefit from his expertise. If you want to learn more, visit his website and listen to his patient testimonies. You won’t be disappointed!  What are you waiting for?  Make an appointment today!

Yale study found no safety issues with long-term ketamine treatment

Researchers at Yale published a new study titled “Acute and Longer-Term Outcomes Using Ketamine as a Clinical Treatment at the Yale Psychiatric Hospital” in Clinical Psychiatry.  In late 2014, Yale began providing ketamine as an off-label therapy on a case-by-case basis for patients who could not participate in research protocols.  The authors observed 54 patients that received IV ketamine infusion for the treatment of severe and treatment-resistant mood disorders such as depression.

“Ketamine is being used as an off-label treatment for depression by an increasing number of providers, yet there is very little long-term data on patients who have received ketamine for more than just a few weeks,” Samuel T. Wilkinson, MD,from the department of psychiatry, Yale School of Medicine and Yale Psychiatric Hospital, told Healio Psychiatry.

The Yale researchers studied the acute and longer-term outcomes in this patient population. Importantly, a subset of patients (n=14) received ketamine on a long-term basis, ranging from 12 to 45 total treatments, over a course of 14 to 126 weeks.  The researchers found no evidence of cognitive decline, increased proclivity to delusions, or emergence of symptoms consistent with cystitis in this subset of long-term ketamine patients.  They also reported that the infusions were generally well-tolerated.

Although this study population was relatively small, limiting the conclusions that can be drawn, this is still an important first step in establishing the long-term safety of ketamine for the treatment of a myriad of diseases that it’s being used to treat.

If you or someone you know is depressed, please make an appointment to see if you are a good candidate for ketamine.  Dr. Ashraf Hanna is located in Clearwater, FL and is one of the leading experts in IV ketamine therapy.  Dr. Hanna is a licensed anesthesiologist and Director of Pain Management at the Florida Spine Institute.  He has performed thousands of infusions and patients travel from all over the world to benefit from his expertise. If you want to learn more, visit his website and listen to his patient testimonies. You won’t be disappointed!  What are you waiting for?  Make an appointment today!

What Fibromyalgia Teaches Us About Chronic Pain

What Fibromyalgia Teaches Us About Chronic Pain

What Fibromyalgia Teaches Us About Chronic Pain

Rethinking the Origin of Chronic Pain
Until relatively recently, most clinicians (and even many pain researchers) considered the majority of chronic pain to be due to ongoing peripheral nociceptive activity (eg, due to damage or inflammation) in peripheral tissues. In a few instances, this lack of concordance between damage/inflammation and pain is well known. For example, nearly all clinicians understand that there is a poor relationship between the results of magnetic resonance imaging or computed tomography scans of the back, and the presence or absence of lumbar pain. However, very few realize that there is not a single chronic pain state where any radiographic, surgical, or pathologic description of peripheral nociceptive damage has been reproducibly shown to reliably identify which individuals will be experiencing pain, or how severe that pain will be. The reason for this appears to be that both the peripheral and central nervous systems (PNS/CNS) play critical roles in determining which nociceptive input detected by sensory nerves in the peripheral tissues will lead to the perception of pain in humans. Many individuals with significant peripheral nociceptive input will not experience pain, and others without any identifiable peripheral nociceptive input will experience severe pain. A central tenet of this review is that within any specific diagnostic category, individual patients may have markedly different peripheral nociceptive and neural contributions to their pain. Thus, just as low back pain has long been acknowledged to have multiple potential mechanisms and thus has sometimes been referred to as a mixed pain state, it is becoming more likely that all chronic pain syndromes may in fact be mixed pain states. This term implies that within each diagnostic category, individuals may have markedly different reasons for their pain. Some individuals will have pain primarily due to peripheral nociceptive input, whereas in others peripheral (eg, peripheral sensitization) or CNS factors (central sensitization, or centralization, of pain via augmented pain processing in the spine and brain) may be playing an equally or even more prominent role in their pain and other symptoms. Making this distinction is critical from a clinical standpoint because both the drug and non-drug therapies that will work for any given chronic pain patient might be much better guided by a nuanced view of the mechanisms of the pain rather than knowing from which of these diagnoses the patient is suffering. This is not a new concept, having first been raised more than a decade ago by Mitchell Max, and later Clifford Woolf and others. However, these authors opined that we should do this in the future; this review suggests that we might finally have made enough scientific progress in the pain field to begin implementing these techniques in clinical practice. img1 Figure 1 briefly describes at least 3 different underlying mechanisms that can be operative in chronic pain states: peripheral nociceptive, peripheral neuropathic, and central neuropathic (or centralized) pain. Some authors use the term neuropathic pain for any pain of neural origin, whereas others reserve this term for conditions where there is identifiable damage to the nervous system. We acknowledge this, but prefer to use the term central (or centralized) pain to refer to the fact that the CNS (rather than the PNS) is prominently involved in maintaining the pain. This distinction between peripheral neuropathic pain (where peripherally directed therapies such as topical treatments, injections, and/or surgery might be helpful, and should be considered) and central neuropathic pain (where these generally are not options) is extremely important. Of note, although specific diagnoses are noted in Figure 1 as being considered peripheral nociceptive, peripheral neuropathic, or central neuropathic (centralized), this is meant to indicate the category in which each of the diagnoses has historically been considered to reside. Again, the emphasis of this review is that some individuals with any chronic pain state have evidence that they have centralized their pain and should likely be treated with centrally acting treatments, whereas other individuals with conditions such as fibromyalgia or irritable bowel syndrome (IBS) may have peripheral contributions to their pain that may need to be identified and treated. Fibromyalgia as the Prototypical Centralized Pain State. The term central pain was originally used to describe individuals who developed pain after a stroke or spinal cord lesion. In this case, central referred to the fact that the lesion leading to pain occurred within the CNS—either spinal cord or brain. More recently, however, the term has expanded to describe any CNS dysfunction or pathology that may be contributing to the development or maintenance of chronic pain. Another term that often has been used to describe this same phenomenon is central sensitization. Using this term can cause some confusion because just like central pain, the original meaning of central sensitization in the pain field referred to a specific spinal cord mechanism that is now realized to be one of many potential causes of augmented CNS pain processing. Central pain, as newly defined, originally was thought to be confined to individuals with idiopathic or functional pain syndromes, such as fibromyalgia, headache, IBS, temporomandibular joint disorder, and interstitial cystitis. These pain syndromes have been shown to be familial/genetic, and to strongly coaggregate in individuals and families. The symptoms experienced by individuals with central pain syndromes have been well characterized and consist of multifocal pain (with a high current and lifetime history of pain in many bodily regions), and a cluster of co-occurring somatic symptoms (ie, fatigue, sleep disturbances, memory difficulties). Even if individuals are identified as having a new onset of a regional pain syndrome, closer questioning often reveals very high rates of pain in other bodily regions, and other somatic symptoms in addition to pain. Screen Shot 2015-12-17 at 3.07.16 PM Using a large Swedish twin registry, Kato and coleagues performed a series of studies first showing the comorbidities with chronic widespread pain. They later examined a number of these central, or functional, pain syndromes and the relationship of symptoms to those of depression and anxiety. These studies clearly demonstrated that functional somatic syndromes such as fibromyalgia, chronic fatigue syndrome, IBS, and headache have latent traits (eg, multifocal pain, fatigue, memory, and sleep difficulties) that are different from (but overlap somewhat with) psychiatric conditions such as anxiety and depression. The notion that there are 2 overlapping sets of traits, one being pain and sensory amplification and the other being mood and affect, also is supported by genetic studies of idio-pathic pain syndromes. Current evidence suggests that genetic factors are approximately 50% responsible for overall sensitivity to experimental pain, and that the same genes that have been identified as increasing sensitivity to experimental pain also make individuals more likely to develop chronic pain over the course of their lifetime. There are at least 5 sets of genes that have been shown to both change an individual’s pain sensitivity and increase their likelihood of developing one or more chronic pain states. These include COMT (an estrogen-sensitive enzyme that may play a more prominent role in females); a number of sodium channel mutations; GTP cyclohydroxylase (GCHI); types 2 and 3 adrenergic receptors; and a potassium channel gene (KCNS). The genes have been most consistently shown to confer a higher risk for pain sensitivity or the development of chronic pain, but not all studies have confirmed these findings. As with most illnesses that may have a familial or genetic underpinning, environmental factors may play a prominent role in triggering the development of fibromyalgia and other central pain states. Environmental stressors temporally associated with the development of either fibromyalgia or chronic fatigue syndrome include early life trauma; physical trauma (especially involving the trunk); certain infections such as hepatitis C, Epstein-Barr virus, parvovirus, and Lyme disease; and emotional stress. The disorder also is associated with other regional pain conditions or autoimmune disorders. Of note, each of these stressors only triggers the development of fibromyalgia and/or chronic fatigue syndrome in approximately 5% to 10% of individuals who are exposed; the overwhelming majority of individuals who experience these same infections or other stressful events regain their baseline state of health. Although fibromyalgia, IBS, and other central pain states were originally felt to be autoimmune or inflammatory diseases (ie, fibrositis, spastic colitis) and then later believed not to be, recent findings are leading to a reconsideration of whether subtle inflammatory or peripheral changes may be responsible for some of the symptoms seen. Furthermore, studies suggest that maintenance of central augmentation requires persistent noxious peripheral input, even in syndromes such as IBS and fibromyalgia, which are characterized by the absence of well-defined, localized, pain-causing lesions. A recent study of 68 patients with fibromylgia and myofascial pain syndromes and 56 patients with fibromyalgia and regional joint pain showed that peripheral trigger-point injections and hydroelectro-phoresis ameliorate fibromyalgia pain and increase pain thresholds at sites distant from the therapeutic interventions, providing further evidence that painful peripheral stimuli contribute to the perpetuation of central augmentation interventions. Role of Central Factors in Classic Peripheral Nociceptive Input Disorders Historically, the “disease” of osteoarthritis (OA) has been viewed primarily as damage to the cartilage and bone. As such, the magnitude of damage or inflammation of these structures should predict symptoms. Population-based studies suggest otherwise; 30% to 50% of individuals with moderate to severe radiographic changes of OA are asymptomatic, and approximately 10% of individuals with moderate to severe knee pain have normal radiographs. Psychological factors do account for some of this variance in pain and other symptoms, but only to a small degree. This failure of peripheral damage, inflammation, or even psychological factors to explain the presence, absence, or severity of chronic pain should not be surprising. To date, no chronic pain state involves a strong relationship between peripheral factors and the level of pain reported.The work done to date supports the hypothesis of OA as a mixed pain state, and in some individuals CNS factors are highly influential. Central factors may be playing a pivotal role in OA, which helps to explain the fact that comorbid somatic symptoms known to be associated with central pain conditions (eg, fatigue, sleep problems) are very commonly present in OA, and are not explained by a purely peripheral model of this disorder. Moreover, both quantitative sensory testing and functional neuroimaging studies suggest that patients with OA display diffuse hyperalgesia to mechanical or heat stimuli, some of which normalizes following hip arthroplasty. This further suggests that the central factors were being at least partly driven by peripheral nociceptive input. Finally, recent randomized controlled trials have demonstrated that compounds that alter pain neurotransmitters centrally such as serotonin and norepinephrine (eg, duloxetine [Cymbalta, Lilly], milnacipran [Savella, Forest], tricy-clics) are efficacious in OA. Screen Shot 2015-12-17 at 3.07.16 PM Basing Pharmacologic Therapy on Underlying Mechanism(s) of Pain Figure 2 shows the classes of drugs that seem most effective in different underlying mechanisms of pain. For peripheral nociceptive, noninflammatory pain states such as OA, treatment guidelines typically recommend first using acetaminophen, and then non steroidal anti-inflammatory drugs (NSAIDs). It is now generally thought that acetaminophen is safer, but less effective, than NSAIDs. Although opioids previously had been considered to be very useful for pain refractory to these treatments, the latest meta-analyses of opioids in OA challenge this notion, and generally recommend against opioid use. Although older studies supported the fact that tricyclic compounds may be effective in OA, these drugs have significant toxicity, especially in the elderly. Because of this, newer drugs that also are likely working by increasing serotonergic and noradrenergic activity, such as tramadol and duloxetine, are more commonly used. Although many in the pain field strongly suspect that these latter centrally acting analgesics (this term is used cautiously because most analgesics have potential peripheral and central mechanisms) will be more effective in individuals with peripheral nociceptive pain that has centralized to date, there have been no studies that have definitively proved this. In inflammatory, peripheral pain states such as rheumatoid arthritis, a whole host of anti-inflammatory or disease-modifying drugs also are used in addition  to the above drugs. It is likely that these drugs both directly decrease pain by reducing inflammation, and also reduce peripheral sensitization that may occur due to ongoing inflammation. The classes of drugs that preferentially work for neuropathic or centralized pain states again include the serotonin-norepinephrine reuptake inhibitors (eg, tricyclics, tramadol, duloxetine) as well as the calcium channel ligands (pregabalin [Lyrica, Pfizer] and gabapentin).Peripheral pain syndromes (including both inflammatory and noninflammatory peripheral pain, and peripheral neuropathic pain) also can be treated with topical agents or injections. Injections of corticosteroids, hyaluronic acid preparations (for OA in joints that can be injected), agents that ablate nerves, or capsa-icin (effective in both OA and neuropathic pain) are all therapeutic options. References 1.    Boden SD, McCowin PR, Davis DO, et al. Abnormal magnetic-resonance scans of the cervical spine in asymptomatic subjects. A prospective investigation. J Bone Joint Surg Am. 1990;72(8):1178-1184. 2.   Max MB. Is mechanism-based pain treatment attainable? Clinical trial issues. J Pain. 2000;1(3 suppl):2-9. 3.   Woolf CJ. Pain: moving from symptom control toward mechanism-specific pharmacologic management Ann Intern Med. 2004;140(6):441-451. 4.   Woolf CJ, Thompson SW. The induction and maintenance of central sensitization is dependent on N-methyl-D-aspartic acid receptor activation; implications for the treatment of post-injury pain hypersensitivity states. Pain. 1991;44(3):293-299. 5.   Clauw DJ, Schmidt M, Radulovic D, et al. The relationship between fibromyalgia and interstitial cystitis. J  Psychiatric Res. 1997;31(1):125-131. 6.   Hudson JI, Pope HG. The concept of affective spectrum disorder: relationship to fibromyalgia and other syndromes of chronic fatigue and chronic muscle pain. Baillieres Clin Rheumatol. 1994;8(4):839-856. 7.   Diatchenko L, Nackley AG, Slade GD, et al. Idiopathic pain disorders—path ways of vulnerability. Pain. 2006;123(3):226-230. 8.   Williams DA, Clauw DJ. Understanding fibromyalgia:  lessons from the broader pain research community. J Pain. 2009;10(8):777-791. 9.   Warren JW, Howard FM, Cross RK, et al. Antecedent nonbladder syndromes in case-control study of interstitial cystitis/painful bladder syndrome. Urology . 2009;73(1):52-57. 10. Kato K, Sullivan PF, Evengard B, et al. A population-based  twin study of functional somatic syndromes.Psychol Med. 2009;39(3):497-505 .
Researchers have discovered the recipe for painlessness

Researchers have discovered the recipe for painlessness

People born with a rare genetic mutation are unable to feel pain, but previous attempts to recreate this effect with drugs have had surprisingly little success. Using mice modified to carry the same mutation, UCL researchers funded by the MRC and Wellcome Trust have now discovered the recipe for painlessness.

‘Channels’ that allow messages to pass along nerve cell membranes are vital for electrical signalling in the nervous system. In 2006, it was shown that sodium channel Nav1.7 is particularly important for signalling in pain pathways and people born with non-functioning Nav1.7 do not feel pain. Drugs that block Nav1.7 have since been developed but they had disappointingly weak effects.

The new study, published in Nature Communications, reveals that mice and people who lack Nav1.7 also produce higher than normal levels of natural opioid peptides.

To examine if opioids were important for painlessness, the researchers gave naloxone, an opioid blocker, to mice lacking Nav1.7 and found that they became able to feel pain. They then gave naloxone to a 39-year-old woman with the rare mutation and she felt pain for the first time in her life.

“After a decade of rather disappointing drug trials, we now have confirmation that Nav1.7 really is a key element in human pain,” says senior author Professor John Wood (UCL Medicine). “The secret ingredient turned out to be good old-fashioned opioid peptides, and we have now filed a patent for combining low dose opioids with Nav1.7 blockers. This should replicate the painlessness experienced by people with rare mutations, and we have already successfully tested this approach in unmodified mice.”

Broad-spectrum sodium channel blockers are used as local anaesthetics, but they are not suitable for long-term pain management as they cause complete numbness and can have serious side-effects over time. By contrast, people born without working Nav1.7 still feel non-painful touch normally and the only known side-effect is the inability to smell.

Opioid painkillers such as morphine are highly effective at reducing pain, but long-term use can lead to dependence and tolerance. As the body becomes used to the drug it becomes less effective so higher doses are needed for the same effect, side effects become more severe, and eventually it stops working altogether.

“Used in combination with Nav1.7 blockers, the dose of opioid needed to prevent pain is very low,” explains Professor Wood. “People with non-functioning Nav1.7 produce low levels of opioids throughout their lives without developing tolerance or experiencing unpleasant side-effects. We hope to see our approach tested in human trials by 2017 and we can then start looking into drug combinations to help the millions of chronic pain patients around the world.”

The findings were made possible by the use of ‘transgenic’ mice, meaning they were modified to carry genetic material from another organism — in this case, the mutation that prevents humans from feeling pain. Precise physiological experiments showed that the nervous systems of the transgenic mice contained around twice the levels of naturally-produced opioids as unmodified mice from the same litter.

“Our results reaffirm the clinical relevance of transgenic mouse models for human diseases,” says Professor Wood. “Studying the mice showed us what was going on in the nervous system that led to painlessness and our findings were directly translatable to humans, as confirmed by the painless patient. Without the work in transgenic mice, none of this would have been possible and we still wouldn’t know how to replicate the effects to help people suffering from chronic pain.”

Story Source:

University College London. “Genetically modified mice reveal the secret to a painless life: Researchers have discovered the pharmaceutical recipe for painlessness.” ScienceDaily. ScienceDaily, 4 December 2015. <>

Journal Reference:

  1. Michael S. Minett, Vanessa Pereira, Shafaq Sikandar, Ayako Matsuyama, Stéphane Lolignier, Alexandros H. Kanellopoulos, Flavia Mancini, Gian D. Iannetti, Yury D. Bogdanov, Sonia Santana-Varela, Queensta Millet, Giorgios Baskozos, Raymond MacAllister, James J. Cox, Jing Zhao, John N. Wood. Endogenous opioids contribute to insensitivity to pain in humans and mice lacking sodium channel Nav1.7Nature Communications, 2015; 6: 8967 DOI: 10.1038/ncomms9967