12 March 2009

A cure for fear?

Some time ago, doctors drew attention to the fact that people who had experienced a severe traumatic experience showed a less pronounced stress reaction when remembering this, if they were previously injected with propranolol – a beta-blocker. The full name of this group of drugs sounds like "beta-adrenergic receptor blockers". It is already clear from it that these substances block the receptors that perceive adrenaline, reducing the effect of its effect on the body – reducing the frequency and strength of heart contractions, reducing blood pressure.

However, it has not yet been known whether such a "side effect" of beta blockers is a temporary phenomenon, or they act for a longer time. To establish whether propranolol is really capable of easing the pain of a difficult memory, Dutch scientists led by Merel Kindt did not act quite humanely.

To begin with, they selected 60 healthy student volunteers and taught them to be afraid of spiders: by showing a picture of a spider, scientists mercilessly electrocuted the subjects (within reason, of course, that is, not causing real pain, but causing irritation). It is not surprising that soon the display of the spider image caused them serious fright, the expectation of an unpleasant experience – and all the symptoms associated with it.

It turned out that if you give a person propranolol before the demonstration, all the symptoms of fright disappear. Moreover, they did not return even after the volunteers underwent a second round of "spider fear training". This may indicate that the traumatic associative connection has been destroyed almost completely.

The same volunteers who were given a placebo needed long–term training to get rid of fear - showing pictures of spiders, but without the accompanying electric discharge. This method is widely used in psychiatric practice today: for example, with the same arachnophobia (fear of spiders), optimal and calm conditions are created for the patient to observe spiders and contact them. This often gives a positive result, but just as often over time, or under the influence of a seemingly inconspicuous event, the phobia returns again.

This was the case with those volunteers in the experiments of Merel Kindt who received a placebo: if they were "taught a lesson" by current discharges again, the fear of spiders returned again. But in the group receiving propranolol, there was no steady return of it.

Apparently, this effect of beta-blocker is due to the fact that it "interferes" with the complex effects of adrenaline on the body and brain. In particular, adrenaline, released in abundance during traumatic experiences, affects the amygdala. This is a special area of the brain involved in the formation of emotions and associated memories. According to some reports, it is disorders in the functioning of the amygdala (two of them – one in each hemisphere) that lead to the appearance of emotional disorders, including anxiety, post-traumatic syndrome, phobias, depression. According to Merel Kindt, it is the blocking of the adrenoreceptors of the amygdala that serves as the basis for the "anti-stroke" action of propranolol.

Other scientists draw attention to the fact that, despite the impressive results that their Dutch colleagues managed to achieve, the observation of the volunteers lasted only three days. And it is unknown whether the fear is not able to return after at least a week. In addition, in their experiment, only one type of reaction was observed – fear, whereas in reality the same post-traumatic syndrome often includes a whole complex of negative experiences, such as anger, shame, and so on. The effect of propranolol on these emotions remains unknown.

"Popular Mechanics" by New Scientist Health publicationNOTE for those who like to experiment on themselves:

Propranolol (Anaprilin, Anaprilinum). Synonyms: Inderal, Obsidan, Propranolol, Stobetin...
...Side effect
From the central nervous system and peripheral nervous system: increased fatigue, weakness, dizziness, headache, drowsiness or insomnia, vivid dreams, depression, anxiety, confusion, hallucinations, tremor, nervousness, anxiety.
From the sensory organs: decreased secretion of lacrimal fluid (dryness and soreness of the eyes).
From the cardiovascular system: sinus bradycardia, AV blockade (up to the development of complete transverse blockade and cardiac arrest), arrhythmias, development (aggravation) of chronic heart failure, decreased blood pressure, orthostatic hypotension, angiospasm (increased peripheral circulatory disorders, cooling of the lower extremities, Raynaud's syndrome), chest pain.
From the digestive system: nausea, vomiting, discomfort in the epigastric region, constipation or diarrhea, liver dysfunction (dark urine, jaundice of the sclera or skin, cholestasis), taste changes, increased activity of hepatic transaminases, lactate dehydrogenase.
From the respiratory system: nasal congestion, bronchospasm.
From the endocrine system: changes in blood glucose concentration (hypo- or hyperglycemia).
From the hematopoietic system: thrombocytopenia (unusual bleeding and hemorrhages), leukopenia.
Dermatological reactions: increased sweating, psoriasis-like skin reactions, exacerbation of psoriasis symptoms.
Allergic reactions: itching, skin rash, urticaria.
Other: back pain, arthralgia, decreased potency, withdrawal syndrome (increased angina attacks, myocardial infarction, increased blood pressure).

Portal "Eternal youth" www.vechnayamolodost.ru12.03.2009

Found a typo? Select it and press ctrl + enter Print version