The pain it is a defense mechanism implemented by our body to protect our body from possible damage. In fact, it is activated following specific nervous stimuli (thermal, physical or inflammatory) which are collected and promptly reach our brain through the spinal cord, which is located inside our spine. This mechanism is shared with many other animal species, ha deep evolutionary roots and it is essential for survival. There are various types of pain, including somatic and psychosomatic, each with its specific usefulness; but when the pain becomes chronic apparently loses its adaptive role, transforming into a challenge for modern medicine. Through a combination of pharmacological therapies and innovative approaches such as neurostimulationscience seeks to alleviate this condition and improve the quality of life of patients.
What pain makes us feel
THE’International Association for the Study of Pain updated its definition for pain in 2020, defining it as “asensory experience and unpleasant emotional experience associated, or resembling that associated, with a actual or potential tissue damage”. This definition underlines both the importance of the subjective and emotional component and its preventive warning function.
From a physiological point of view, pain is the result of a sophisticated alert system involving thenervous system. The transmission of pain begins in the nociceptorsspecialized receptors, which detect harmful stimuli. This occurs thanks to cells equipped with special proteins that change when subjected to certain stimuli, such as notable temperature changes, stretching or when exposed to inflammatory molecules.

From the modification of these receptor proteins, a signal is generated which then travels along the nerve fibers to the spinal cord. Here a first gross processing occurs, in which this signal is modulated by special neurons, called interneuronswhich are able to amplify or inhibit this signal. Subsequently, the signal reaches the brain through the thalamuswhich acts as a sorting station, directing it towards the somatosensory cortexwhich identifies location and intensity, and towards limbic areasresponsible for emotional and mnemonic component. It is precisely in this phase that sensorial and emotional integration of the pain we were talking about occurs.

But the experience of pain, even if it may seem like it counterintuitiveis not passively received by the brain: in a certain sense it also comes produced and modulated by the brain itself. The signals that are transmitted from the periphery to the brain are in fact intercepted by a system of neurons called descending routeswhich modify and modulate pain information. Therefore, some centers of the brain they contribute to shaping the painful experience which they will then elaborate. This system is mainly concerned with reducing perceived pain and makes use of the famous ones endorphins: real analgesics produced by our body.
Why does pain exist? The evolutionary reasons
Although pain is perceived as a negative experience, it has a fundamental role for our survival. It works as a warning system that alerts us to imminent dangers, preventing us from causing further damage to our bodies.
Neurotransmitters and structural elements of our pain perception system are surprisingly preserved in much of the animal kingdomsuggesting ancient origins. The presence of these shared elements indicates that pain, in its essence, is a basic mechanism for the survival of many complex organisms, present in countless species, from the simplest marine creatures to mammals.
In addition to recognizing the evolutionary roots of pain, it is essential to understand the specific conditions that make it a advantageous adaptive trait. For pain to establish itself as an evolutionary advantage, the environment must present significant challenges to survival, such as the presence of predators or competition for resources. In such environments, the ability to detect and respond quickly to injuries or threats potentials can mean the difference between life and death.

Also longevity of the species is a determining factor. If lifespan is short, the long-term benefits of pain sensitivity andlearning based on pain may not be sufficient to compensate for the energetic costs of maintaining a complex pain perception system. In contrast, in animals with a longer lifespan, pain can become a powerful learning toolallowing them to remember and avoid harmful experiences in the futurethus increasing their chances of survival and reproduction.
In essence, pain evolves as an adaptive trait when animals live in dangerous environments and have a sufficient lifespan to benefit from the lessons learned through painful experiences.
Pain management
However, sometimes the pain can just become annoying or even a hindrancein healing. Fortunately, science has developed many strategies to ease pain, from medications to behavioral interventions.
The drugs analgesics They work by peripherally blocking pain signals or reducing inflammation. The opioids insteadbind to receptors present in the central nervous system, limiting the reception of pain. There are also methods that do not involve drugs, such as neurostimulation which uses the implantation of tiny electrodes to modify the painful electrical impulses that reach the brain. These therapies are used particularly for chronic pain.

The chronic pain it is a clear example of pain that is apparently dysfunctional and has no adaptive value. It is defined as a pain that persists or becomes recurrent for 3 or more months. While in fact the pain is acute sign of damagechronic pain itself becomes a diseasedue to an alteration of the nervous system that amplifies or maintains the painful sensation even in the absence of a real cause. Common examples include chronic low back pain, fibromyalgia, and neuropathic pain, such as that associated with diabetic neuropathyconditions that can significantly compromise patients’ quality of life.
This phenomenon represents one of the more complex challenges and debates of modern medicine. Unlike the clear alarm signal represented by acute pain, the The biological significance of chronic pain remains poorly understood and debated and its treatment is one of the most current challenges of contemporary medicine.