An overall stress/anxiety complex with environmental, physiological, psychological, and behavioural components includes stress and anxiety as complementary characteristics. Categorical definitions of stress and anxiety are not helpful given the current state of our understanding. A transdiagnostic approach more accurately captures their overlapping phenomenology and processes than artificially dividing them. Stress and anxiety can become conditioned reactions to environmental stimuli when they are introduced into an organism's learning history. Stress and anxiety include autonomic protective alarm, according to neurobiology. include neurohumoral reactions originating predominantly from the hypothalamic-pituitary-adrenal axis and sympathetic nervous system responses. Stress and anxiety are evolutionary adaptations that help an organism deal with difficult situations it faces in its environment. When the stress/anxiety complex is overworked, the body may experience allostatic overload as it tries to reestablish homeostasis.
Numerous physical and mental disorders can develop or deteriorate when stress and worry are too much for a person to handle, or when coping mechanisms are insufficient. The most prominent example of this phenomena is anxiety disorders. In anxiety disorders and other related mental diseases, the kind, intensity, and persistence of stress are particularly crucial factors. Even in genetically healthy individuals, catastrophic stress can result in posttraumatic stress disorder (PTSD). Even with less stress, genetically predisposed individuals can acquire anxiety illnesses. The intensity and duration of stress should play a significant role in how cases of anxiety and associated illnesses are conceptualised.