It should be noted here that nerve cells die constantly, every day we lose a certain number of neurons, and this is a biologically programmed process. Each neuron has an axon and a large number of dendrites, through which it connects with other neurons and forms a network that performs a certain function, in other words, the number of connections is an indicator of activity, if a neuron does not have them, it means that it does not participate in the processing information and transmission of signals, and therefore simply consumes energy, and you can get rid of such. It should also be said that the statement "nerve cells do not recover" has long been denied, and that our nervous system is static and incapable of regeneration, neurons are very much restored. In the brain there are certain zones (subventricular zone and subgranular zone) in which the process of neurogenesis (the formation of new cells) takes place, some of them die, and some form new synaptic connections and are included in the general process. Now this issue is being studied even more actively, in order to be able to stimulate neurogenesis from the outside, in order to treat various neurodegenerative diseases.
Back to the original question, stress is a very vague concept. For the body, in principle, any effect is stress, because any information we perceive naturally leads to the excitation of certain neurons and, accordingly, to the production of neurotransmitters, hormones, and so on. But there is also such a thing as "distress", it is, so to speak, a suprathreshold stimulus that leads to over-activation of various areas of the brain and body systems. Cortisol is naturally considered a stress hormone, as well as under stress the level of norepinephrine and adrenaline increases, the amount of glutamate (an activating mediator) in the brain increases, and the level of GABA decreases (an inhibitory mediator, which is also responsible for the ability of the brain to recover to a state of rest) ... An increase in glutamate is a natural reaction to stress, an increased amount of it leads the nervous system to a state of hyperexcitation, so that you can respond to a stressful situation as quickly as possible, make any decisions or actions. But under chronic stress this will take mostly negative consequences, constantly increased excitement, a decrease in the amount of GABA - will lead to overexcitation of neurons, they will not die directly from this, they will simply "turn off" from work and reduce their activity. But chronic stress in the long term can disrupt not only the mechanism of signal transmission between neurons and the biochemistry of neurotransmitters, but also the metabolic processes of the body. And just because of these disorders, neurons can die, stress disrupts glucose metabolism in the body, oxygen metabolism, lipid metabolism, increases blood pressure (which can play a cruel joke in older peopleher, with weakened vessels, on which, moreover, a lot of atherosclerotic plaques have already formed, which in theory (and in practice) can lead to a stroke in general, and this is a massive genocide of nerve cells), a short-term increase in the activity of the thyroid gland, is replaced by a persistent inhibition of its function , which in turn completes the vicious circle, since The main area of action of thyroid hormones is metabolism and energy production. Ultimately, we can say that neurons under chronic stress can die due to the resulting lack of nutrients, vitamins, due to oxygen starvation, associated, among other things, with impaired blood supply to the brain tissue, due to intoxication with various waste products, for example, stress increases the level of ketone bodies, which in turn are very toxic to the body. Finally, I did not describe the biochemical and metabolic disorders in full, because I have not yet taken into account a whole bunch of different factors, for example, during stress, insomnia may be observed, or depression may develop, and these conditions will only aggravate the situation, in the future, instead of stress, they may lead to somatic (from organs and systems) pathologies ... Plus, I also did not fully describe the changes in the hormonal background, the exchange of cytokines, other neurotransmitters and hormones, which also have a certain role in the body, also change, and a violation of their metabolism and function leads to various problems. All this is true for really strong stress that persists for a long time, in which the person himself is not interested in helping himself, does not go to the doctor, but on the contrary begins, for example, to drink alcohol, and this, by the way, it greatly (!) greatly worsens the prognosis and further disrupts the work of the body and the central nervous system in particular.
Stress from the point of view of medicine - any influence that leads to dysfunction of the body. Stress can be "good" (eustress) - jogging, for example, or "bad" - distress (concussion, stroke). Cells die from direct mechanical action, from a lack of blood circulation, metabolic disorders, the list goes on, but neurons are fragile cells.