Many describe dependency as primarily being a fear-based disease. People with dependency usually describe being fearful from a young age. Apart from fearful behaviour this often led to worry-lines affecting the forehead, finger-nail biting and horrid dreams/nightmares even as a child.
This article will highlight some of the research into dependency and fear.
The amygdala and fear
It seems that one of the most important areas of the brain responsible for developing fear is the almond-shaped amygdala. The amygdala contains nerve cells or neurons which are connected to
1. The sympathetic nervous system (via the hypothalamus).
The amygdala sends impulses which control heart rate, breathing, bowel/bladder activity and sweating. The response to fear is often “fight, fright or flight” or even soiling of the underwear in some.
2. The olfactory bulb.
This sends impulses related to smell to the amygdala. Perhaps this leads to the phrase “smelling fear”.
3. The frontal lobes.
The amygdala sends impulses to the frontal lobes which invoke ideas, thoughts and feelings often from previous memories related to fear.
The outer part or lateral amygdala may be more involved in the development of fear than the inner or medial part.
MRI head scans and the amygdala.
MRI head scans have shown that the amygdala may be larger in psychiatric disorders which are predominated by negative emotions e.g. depression and some personality disorders. However, the amygdala may be smaller in patients with psychiatric disorders associated with positive emotions e.g. adolescents with bipolar disorder.
Fear/stress and neuron structure in the amygdala and frontal lobes
In order to help understand the following findings please read the tree model of brain disorders
Radley et al noted that loud noise and electric shock exposure resulted in 35% more dendritic spines being formed in part of the outer or lateral amygdala.
It has also been noted that repeated stress induced dendritic spine loss in the pre-frontal cortex.
How can these findings be related to clinical behaviour?
It seems that generally speaking, the fewer dendritic spines there are in the frontal lobes the more negative a patient`s ideas are, resulting in negative thoughts, feelings and behaviour.
These ideas are characterised by self-pity, resentment, fear and dishonesty.
We also know that there are fewer dendritic spines in the part of the brain perceiving sound (auditory cortex) of patients with schizophrenia which is associated with auditory hallucinations.
It is possible that increased dendritic spines in the outer amygdala and decreased dendritic spines in the frontal lobes go hand-in-hand i.e. increased fear provokes increased negative emotions and increased heart rate in a vicious cycle leading to psychiatric symptoms.
The immune system and the amygdala
It is now recognised that the brain`s immune system is abnormal in most if not all psychiatric disease. It does not appear that there any studies on an Internet search correlating amygdala volume and immune activity e.g. TNF levels. Inflammation of the dendrites is called dendritis.
As dependency progresses inflammatory markers e.g. TNF increase, although intially inflammatory markers as reduced i.e. alcohol and opioids have a bimodal effect.
Genetics, the amygdala and the frontal lobes.
Early studies have confirmed that some genes are associated with abnormalities of the amygdala-frontal cortex system and developing depression.
Alcohol and the amygdala
In an early experiment Professor Pandy discovered that alcohol increased dendritic spine density in the inner or medial amygdala but not in the outer or lateral amygdala of rats. This led to reduced anxiety. However, when the alcohol was withdrawn the dendritic spines decreased in density in the medial nuclei but not the lateral nuclei.
Perhaps this is how “Dutch courage” works i.e. having a stiff drink before approaching a fearful event may result in dendritic spine growth in the inner amygdala?
However, it is known that chronic alcohol-dependency is associated with loss of frontal lobe dendritic spines and frontal lobe volume.
Opioids and the amygdala
The amygdala and frontal lobes have far more opioid receptors than other parts of the brain. Opioids seem to have an anti-inflammatory effect in early dependency but are pro-inflammatory in late-dependency i.e. they have a bimodal effect. Opioids eventually result in decreased dendritic spine numbers in the brain.
In one study opioids inhibited the outer amygdala function i.e. reduced fear. In another study this year it was found that opioid withdrawal made the inflammation in the brain worse.
Most psychiatric diseases are now realised to be characterised by
Immune system abnormalities due to exposure to substances either absorbed by the body (immunogens) or made by the body (auto-immunogens)
Structural changes in nerve cells (neurons) especially dendritic spines
Clinical features often correlated with dendritic spine density
Excessive fear is one of the main reasons why people with dependency initially find solace in a drink or drug. This comfort may be related to reduction in immune activity and altered dendritic spine numbers in the amygdala and frontal lobes which are rich in opioid receptors.
However, with continued use of alcohol or drugs, the anti-inflammatory effect converts to a pro-inflammatory effect and inflammation of the amygdala or amygdalitis. Fear escalates and more alcohol or drugs are required to achieve the desired effect. Eventually alcohol and drugs cause fear although the patient without insight will not realise this.
Progressive alcohol-drug amygdalitis may be yet another way of looking at the fear-based illness of dependency.
It is interesting neurologists now researching the effect of meditation on the brain have discovered that meditation reduces amygdala activity and increases frontal lobe activity on functional MRI scanning. This may explain the beneficial effects of meditation on fear.
Amygdala – Wikipedia
Associative Pavlovian conditioning leads to an increase in spinophilin-immunoreactive dendritic spines in the lateral amygdala
Repeated Stress Induces Dendritic Spine Loss in the Rat Medial Prefrontal Cortex
5-HTT genotype effect on prefrontal-amygdala coupling differs between major depression and controls.
Effector Immediate-Early Gene Arc in the Amygdala Plays a Critical Role in Alcoholism
The Role of TNFα in the Periaqueductal Gray During Naloxone-Precipitated Morphine Withdrawal in Rats
Functional neural correlates of mindfulness meditations in comparison with psychotherapy, pharmacotherapy and placebo effect. Is there a link?