Verbal Suggestion’s Effect on Analgesia

Today it seems clear that the experimental manipulation used to induce placebo analgesia plays a fundamental role in the magnitude of the response. Among the different manipulations that have been performed, both the type of verbal suggestions and the individual’s previous experience have been found to be important. Verbal suggestions that induce certain expectations of …

The Lateral and Medial Pain Systems in Alzheimer’s Disease

The lateral and medial pain systems are affected differently in Alzheimer’s disease. Both the primary somatosensory cortex and some thalamic nuclei, which belong to the lateral pain system, are relatively unaffected by the histological changes that characterize Alzheimer’s disease, thus indicating that a preserved sensory-discriminative function should be expected. By contrast, the intralaminar thalamic nuclei, …

Placebo acceptability in chronic pain patients: More dependent on application mode and resulting condition than on individual factors

Placebo effects can be very effective in certain pain conditions, but their use is still highly controversial. Several studies show that patients would accept a placebo treatment under certain circumstances, particularly when they are informed prior to the treatment or when there are no effective treatment alternatives. This study examines the question, which factors influence the degree of acceptability of a hypothetical placebo application.

How Pain Works

Let's say that you stub your toe. Nerves in the toe known as nociceptors, tasked with sensing pain, go into action. They send messages to the spinal cord that pain has occurred; the worse the stub, the more rapidly and powerfully they fire. The spinal cord then releases neurotransmitters to the brain's thalamus, communicating with the …

Phantom Limb Pain: Mechanisms and Treatment Approaches

The vast amount of research over the past decades has significantly added to our knowledge of phantom limb pain. Multiple factors including site of amputation or presence of pre-amputation pain have been found to have a positive correlation with the development of phantom limb pain. The paradigms of proposed mechanisms have shifted over the past years from the psychogenic theory to peripheral and central neural changes involving cortical reorganization. More recently, the role of mirror neurons in the brain has been proposed in the generation of phantom pain. A wide variety of treatment approaches have been employed, but mechanism-based specific treatment guidelines are yet to evolve. Phantom limb pain is considered a neuropathic pain, and most treatment recommendations are based on recommendations for neuropathic pain syndromes. Mirror therapy, a relatively recently proposed therapy for phantom limb pain, has mixed results in randomized controlled trials. Most successful treatment outcomes include multidisciplinary measures. This paper attempts to review and summarize recent research relative to the proposed mechanisms of and treatments for phantom limb pain.

Nonconscious Activation of Placebo and Nocebo Pain Responses

The dominant theories of human placebo effects rely on a notion that consciously perceptible cues, such as verbal information or distinct stimuli in classical conditioning, provide signals that activate placebo effects. However, growing evidence suggest that behavior can be triggered by stimuli presented outside of conscious awareness. Here, we performed two experiments in which the responses to thermal pain stimuli were assessed. The first experiment assessed whether a conditioning paradigm, using clearly visible cues for high and low pain, could induce placebo and nocebo responses. The second experiment, in a separate group of subjects, assessed whether conditioned placebo and nocebo responses could be triggered in response to nonconscious (masked) exposures to the same cues. A total of 40 healthy volunteers (24 female, mean age 23 y) were investigated in a laboratory setting. Participants rated each pain stimulus on a numeric response scale, ranging from 0 = no pain to 100 = worst imaginable pain. Significant placebo and nocebo effects were found in both experiment 1 (using clearly visible stimuli) and experiment 2 (using nonconscious stimuli), indicating that the mechanisms responsible for placebo and nocebo effects can operate without conscious awareness of the triggering cues. This is a unique experimental verification of the influence of nonconscious conditioned stimuli on placebo/ nocebo effects and the results challenge the exclusive role of awareness and conscious cognitions in placebo responses.