Table of contents:
- Predisposition towards anxiety disorders
- Psychophysiological aspects
- Patients with specific phobia
- Social phobias
- TAG
- Panic disorder
- Biochemical and neurological aspects
- Neuroendocrine responses
- Neurobiological aspects
We usually know what anxiety is and what are the symptoms that it causes on a physical and emotional level, but on many occasions we do not know where this condition comes from and why there are people who suffer from anxiety to a greater extent than others. The truth is that not all of us have the same predisposition to feel anxiety and this has a biological and a psychological part. In this Psychology-Online article, we are going to address the topic of biological theories of anxiety.
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- Psychophysiological aspects
- Biochemical and neurological aspects
Predisposition towards anxiety disorders
Not all individuals have the same biological vulnerability for anxiety disorders to develop and maintain.
Sandin's conclusions on commenting on Torgersen's work:
- Evidence that hereditary factors may play an important role in anxiety disorders: Agreement percentages: 34% in monozygotic twins and 17% in dizygotic twins.
- The development of generalized anxiety disorder (GAD) shows no evidence of being influenced by hereditary factors: rates of 17% for monozygotic and 20% for dizygotic.
- For the rest of the anxiety disorders, the concordance rates are practically equivalent: 45% and 15% for monozygotic and dizygotic, respectively.
- In anxiety disorders there appears to be an important hereditary component of family transmission (except in GAD).
- Anxiety disorders seem to have a genetic transmission independent of that found in depression and somatoform disorders (hypochondriasis and hysterics).
What is inherited is a vulnerability (diathesis) to develop an anxiety disorder in general; a specific disorder itself is not inherited.
Psychophysiological aspects
Clinical anxiety has been associated with hyperactivity of the autonomic and somatic nervous systems.
Main types of response:
- Electrodermal activity (increase except CPR habituation),
- Cardiac activity (increase except cutaneous blood supply)
- Muscle activity (increase),
- Respiratory activity (increase),
- Brain electrical activity (increase in beta voltage and P300 amplitude, and decrease in alpha voltage and contingent negative variation *),
- Pupillary dilation (increase),
- Changes in PH (increase in blood).
* Electroencephalographic evoked potential that occurs when a subject makes a relevant association between two stimuli.
Patients with specific phobia
They do not present evidence of psychophysiological alteration. On the other hand, if they are associated with strong autonomous responses (increase in electrodermal activity, heart rate, blood pressure, etc.). Exception: blood-wound phobia: Biphasic cardiovascular response: sympathetic activation followed by a sharp drop in blood pressure and cardiac activity.
Social phobias
Psychophysiological responses depend on whether the phobia is generalized (high levels of sympathetic activation) or circumscribed (similar to that of specific phobia). Not all patients respond in the same way to social stressors: Öst separates them into two groups: With or without an increase in heart rate (it is associated with a decrease in social skills).
TAG
Being a chronic alteration of anxiety, it manifests high levels of psychophysiological tone. Despite stressful situations, they show sympathetic activity equal to normal individuals.
Panic disorder
Strong sympathetic reactions during the panic attack (spontaneous and induced). There are some exceptions. They have been explained by sudden decrease in vague tone. Important role of all the psychophysiological manifestations related to hyperventilation (increase in blood pH that contrasts with a decrease in saliva and skin pH).
Biochemical and neurological aspects
Neuroendocrine responses
- The neuroendocrine system is related to stress as well as anxiety.
- An increase in anxiety states implies an increase in the secretion of thyroxine, cortisol, catecholamines and certain pituitary hormones (prolactin, vasopressin, growth hormone).
- The hypothalamic-pituitary-adrenal system has been related to anxiety and stress, manifesting an increase in activation in the mentioned axis: hypersecretion of systemic cortisol.
- Cortico-adrenal activation is associated with a certain degree of specificity to uncontrollable situations (depression).
- Catecholaminergic hyperarousal states tend to be linked more to threatening situations of loss of control and underlying emotions (anxiety).
Neurobiological aspects
One of the best known theories has proposed that anxiety is related to increased noradrenergic activity (locus coeruleus overactivity):
- Electrical stimulation of the locus coeruleus induces anxiety responses and panic attacks.
- The stimulation of central beta receptors and the blockade of alpha-2 receptors also produce anxiety and panic responses.
Based on the anxiolytic effect of benzodiazepines, the possible role of an alteration of the GABA system in the etiology of anxiety has been highlighted.
Currently, anxiety tends to be explained by integrating the noradrenergic and serotonergic systems, on the one hand, and the responses of anxiety and depression on the other.
Eison: A disturbance of the dynamic interactions between catecholaminergic and serotonergic neurotransmitters exists in both anxiety and depression (Manipulation of the serotonergic system affects noradrenergic tone).-> An alteration in the balance of serotonergic neurotransmission contributes to both disorders (anxiety associated with excess and depression with deficiency).
Gray: Anxiety is generated from the stimulation of the behavioral inhibition system located in the limbic structures of the brain and connected to the brainstem and subcortical regions. SIC can be stimulated by punishment indicators, non-reward signals, and innate fear stimuli.
Ledoux: Importance of the thalamus amygdala pathway (directly communicates the thalamus with the amygdala) in emotional reactions: This pathway allows emotional responses to begin in the amygdala, before we are aware of the stimulus that makes us react, or that we identify the sensations experienced.
It has enormous adaptive value:
- The primal emotional memory is stored in the amygdala.
- Emotional memory can be inherited (phylogenetic memory) or it can be learned.
This article is merely informative, in Psychology-Online we do not have the power to make a diagnosis or recommend a treatment. We invite you to go to a psychologist to treat your particular case.
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