Biology Reference
In-Depth Information
can determine the outcome. But, as already mentioned, mild engagements of defence
reactions occur frequently in modern life, inducing the same, though, milder bodily
changes, indicating an appropriate balance between stimulus strength and extent of
engagement. The acute defence reaction is thus an important survival reaction and by
nature advantageous for the organism. One important exception is some pathological
situations, particularly in the presence of coronary insufficiency or myocardial dis-
order, and recent studies show that patients with coronary artery disease may show
exaggerated platelet and hemodynamic reactivity to mental stress, compared with
healthy individuals, partly explaining the pathophysiological processes underlying
emotional triggering of acute cardiac events and, in worse cases, sudden death
[37]
.
Further, as previously mentioned, chronic or frequent episodic activations of defence
reactions can in the long run seriously contribute to cardiovascular diseases such as
primary hypertension
[3,38]
. One should, however, be aware that this relationship is
complicated and many factors such as genetics, individual differences in vulnerabil-
ity, interpretation, experience and physiological reactivity all contribute to the acute
and the chronic outcome of environmental stimuli.
11.4.2 Defeat Reaction
This characteristic reaction pattern - which in view of serious long-term effects
may even be more important than the defence reaction - is induced, for example,
when animals are exposed to situations that overwhelm their coping mechanisms.
The behavioural side is characterized by withdrawal and suppressed physical activ-
ity. In man, this reaction is strongly involved in e.g. deep sorrow or when situations
are experienced as being beyond hope and rescue or, in milder forms, as frustrating
or bleak. In animal research, the defeat reaction is linked to an activation of the
HPA-axis, as explored by e.g. Henry and others
[39]
. In situations experienced as over-
whelming, withdrawal and passivity, typical for defeat reactions, is appropriate and
generally beneficial. However, intense and prolonged activation due to long-lasting
effects of stressors or inability to turn off stress responses can in the long run have
serious consequences for health and end up in disease.
The disturbed release of glucocorticoids can contribute to severe suppression of
the immune system, which in a number of ways can affect health, as discussed in
other chapters of this topic. The metabolic disturbances typical of the metabolic syn-
drome have also been found to be related to disturbances in the HPA axis
[40]
. The
metabolic syndrome is to a great extent lifestyle-related, as both diet and inactivity
play significant roles for the development and the clinical consequences of the syn-
drome. Moreover, recent data from the Whitehall study further support that psycho-
social factors are of great relevance for the development of the metabolic syndrome
[5]
and together with predisposing genetic elements, the situation becomes most
complex, to which comes that glucocortiocoids affect food intake.
It should be remembered that “civilisation disorders” like primary hypertension
and the metabolic syndrome are rare, indeed, in primitive human society, while they
in modern hectic life are becoming more and more prevalent even in younger individ-
uals, and hypertension is often seen as the most prevalent component of the metabolic
