Blood pressure and Headaches, Part 2: do surprising findings cause confusion?

One particularly interesting observation has been a topic of discussion among experts for some time. This is a theory which has been around for more than a century: the theory of so-called hypalgesia in patients with high blood pressure. The term “hypalgesia” describes the fact that the general pain sensitivity of people with high blood pressure is reduced. This was first extensively scientifically described in 1980 and subsequently confirmed through further studies. This solidified an assumption which had already been set out by the New York doctor Theodore C. Janeway in 1913, according to which people with high blood pressure fundamentally have a raised pain perception threshold. With regard to the connections between headaches and high blood pressure which we described in part 1 of our article, the following question arises: if people with high blood pressure do not sense pain as quickly as people with normal or low blood pressure, how is it possible that high blood pressure patients experience headaches more frequently than people without high blood pressure?

What was evolution thinking? A possible solution to the puzzle…

There has not yet been any clarification on the control pathways which lead to a reduced pain sensitivity with high blood pressure. What seems certain is that the body’s own regulation of blood pressure plays a role. It ensures the control and, where applicable, also the necessary adjustment of the blood pressure. This occurs with the help of control processes to which, among other things, our nervous system also contributes. In addition to their pressure-regulating function, the involved nerves are also connected to our pain perception. Moreover, there is also contact with further central control processes, which contribute, for example, to the processing of stress, aggression, readiness to escape, or also relaxation. Scientists who focus on these complicated connections also refer to a “reward system” with regard to reduced pain perception. This is always activated when we are particularly exposed to stress. In this kind of situation, there is often an increase in blood pressure.

If we take a look at the ancestral development of humans over many thousands of years, the reason behind these processes also becomes clear: if an organism experiences severe stress, this was often linked to a danger to life for early humans – for example, in the form of predatory animals or foes. Thus, blood pressure could increase in these moments, with the aim of ensuring heightened fight or flight readiness in the face of this kind of threatening situation. For this reason, pain perception should also be reduced as much as possible, so that the organism is not “unnecessarily” held up or paralysed by pain, but is maximally responsive. This could explain the original purpose of the temporary increase of blood pressure in stress situations. From today’s perspective, we would consider these – at first somewhat strange – interactions to be a remnant from our history of becoming human.

The wide field of blood pressure occurrences

Pain perception appears to be only one of many aspects which are connected to current or long-term blood pressure occurrences. Presumably, we must place them in a wider context with the numerous regulatory processes which are responsible for maintaining balance in our organism (so-called “homeostasis”) in many cases. In addition, it must be noted that the theory of reduced pain sensitivity described above pertains to general pain perception. Many studies on this topic were in fact not carried out on headaches, but on different types of pain. This inevitably always raises the question of whether and to what extent the obtained findings are applicable to other or even all forms of pain. This has not yet been answered.

What has not been researched yet

Based on the findings regarding the simultaneous occurrence of high blood pressure and, generally, headaches as well as, more specifically, migraine, further possible research questions arise:

- If someone who is predisposed to migraine also suffers from high blood pressure, they would have a reduced pain perception according to this theory. However, the question arises whether if they experience a migraine attack, the pain still prevails due to its tremendous strength.

- Can we assume that the headache which is actually felt would be even more severe without the moderating conditions of high blood pressure than what is actually perceived by the affected person?

- Is migraine, as an independent neurological illness, fundamentally subject to rules which cannot be controlled or can only be controlled insufficiently by the body’s balance regulation?

- Do headaches generally occur when these regulatory mechanisms are working to the limit or if their effectiveness is otherwise impaired or limited? This way, the effects of regulation would possibly have little to no impact on the development and perception of headaches.

Despite or precisely because of the continued great need for research in this area, the current advice for everyone suffering from headaches or migraine is still to become familiar with your own pain as much as possible. If you know your personal triggers for headache or migraine attacks, you can integrate your preventative behaviour into your daily life as effectively and sustainably as possible. This way, you are independently intervening in your personal headache situation and can therefore carry out prevention in the best sense.