October 29, 2011
Hypothyroidism And Fear Memory

If you find your personality changing so that you experience emotional alterations, memory impairments and perhaps a heightened formation of fear memories you might want to get your thyroid level checked.

Hypothyroidism is the most common hormonal disease in adults, which is frequently accompanied by learning and memory impairments and emotional disorders.

At least in rats cutting out thyroid hormone causes increased formation of fear memories and general increase in formation of emotional memories.

However, the deleterious effects of thyroid hormones deficiency on emotional memory are poorly understood and often underestimated. To evaluate the consequences of hypothyroidism on emotional learning and memory, we have performed a classical Pavlovian fear conditioning paradigm in euthyroid and adult-thyroidectomized Wistar rats. In this experimental model, learning acquisition was not impaired, fear memory was enhanced, memory extinction was delayed and spontaneous recovery of fear memory was exacerbated in hypothyroid rats. The potentiation of emotional memory under hypothyroidism was associated with an increase of corticosterone release after fear conditioning and with higher expression of glucocorticoid and mineralocorticoid receptors in the lateral and basolateral nuclei of the amygdala, nuclei that are critically involved in the circuitry of fear memory. Our results demonstrate for the first time that adult-onset hypothyroidism potentiates fear memory and also increases vulnerability to develop emotional memories.

Lots of older people have lower thyroid hormone output. So the potential scale of similar impact on humans is quite large.

The researchers wonder whether people suffering from post-traumatic stress have thyroid hormone levels that aren't right.

Furthermore, our findings suggest that enhanced corticosterone signaling in the amygdala is involved in the pathophysiological mechanisms of fear memory potentiation. Therefore, we recommend evaluating whether inappropriate regulation of fear in patients with post-traumatic stress and other mental disorders is associated with abnormal levels of thyroid hormones, especially those patients refractory to treatment.

I hesitate to even suggest this idea: Some day governments could use hormone manipulation as part of interrogations. Imagine getting your hormones altered so that you feel intense fear. Without even using physical torture it will probably become possible to evoke a large range of emotions. Interrogators could become emotional state conductors.

What would be helpful: An emotional weather forecast based on the biochemical state of your body. Imagine embedded sensors that get fed into a smart phone app to tell you how the biochemical state of your body is altering your ability to think clearly. The data could be processed a personal emotional and cognitive weather forecast based on biochemical considerations. Such an application could advise you avoid situations you aren't up to dealing with, suggest diet alterations, exercise, or to get more sleep to get your brain biochemistry back into a state that allows you to function near your peak.

A more advanced version of an emotional weather forecaster could integrate details about your work schedule, relationship status (e.g. by processing phone calls into text and then analyzing them for signs of arguments and break-ups), and other life circumstances to come up with more sophisticated advice based on integrating many different factors from your life. Really, I think it only a matter of time until such an application exists and works well.

Share |      Randall Parker, 2011 October 29 03:12 PM  Brain Emotion Alteration

Demolition Man said at October 29, 2011 8:31 PM:

It turns out that in this industrialized world, many people have seemingly normal thyroid levels (normal TSH) but they still have insufficient T3 levels (the biologically active form of thyroid hormone T3) because pollution and stress depletes the necessary T3 levels, and this is missed by routine blood tests that only check for the TSH (thyroid stimulating hormone produced by the pituitary gland).

Here is a home test kit which combines a blood spot test for thyroid levels plus a saliva test for cortisol (stress hormone):


If the T3 level is significantly below the middle of the reference range, even if it is not outside the reference range, then a small dose of thyroid supplements (natural or synthetic) can greatly improve your concentration and memory.

If you take the test above and if the T3 level is below optimal middle of the reference range, you should see a thyroid doctor who might write a prescription for thyroid medication (natural or synthetic) which is very cheap. Actually it is known that even synthetic thyroid medication T4 is not only an exact copy of the natural thyroid hormone T4, but that it even lowers the risk of cancer according to some clinical trials. Before synthetic thyroid supplements T4 and T3 were invented several decades ago, already during the 19th century animal thyroid supplements were used.

Demolition Man said at October 29, 2011 8:47 PM:

But the levels of thyroid hormones also interact with the levels of the stress hormone cortisol as well as the testosterone levels. When one of these three hormone levels are distorted, the other two are affected also. Another complication is that both thyroid hormone levels (T4 and T3) as well as the testosterone, have both the regular and "free" versions. The "free" versions are the biologically available versions. The "Free T4", "Free T3", "Free testosterone" can be very low even when the regular T4, T3, and testosterone levels are high. This is why the blood and saliva tests must measure also the free versions to compare with the regular versions.

If you have a chronic mild ulcer or irritable bowel syndrome, or any kind of chronic inflammation of the stomach or intestine, this can dramatically distort the thyroid free T3 levels and cortisol levels, as well as the free testosterone levels. When there is any stress (emotional or real injury, etc), then the patient would lose courage and will power because the biologically active version Free T3 and Free testosterone can decline dramatically even though the blood tests measuring regular testosterone and regular T3 are normal.

In both Nazi Germany and the former Soviet Union, prisoners in concentration camps were poisoned with excess fluoride that was added to their water or food, to destroy their thyroid functions, so that they would not have the will power to revolt or escape.

bbartlog said at October 30, 2011 7:12 AM:

'Some day governments could use hormone manipulation as part of interrogations.'
Pretty sure the US already at least *checks* the levels of stress hormones (cortisol) in some of the subjects of the enhanced interrogation program. Anyway, I would expect that the ability to turn off the parts of the brain responsible for resisting interrogation will be developed pretty soon, at which point the use of indirect methods like hormonal manipulation will be inefficient. Which is not to say that that wouldn't work as well.

Brain boy said at October 31, 2011 5:53 AM:

Actually I found that results very interesting, as indeed thyreoid levels do have a majour impact on many pschological and physical functions in the body. We all know the "hyper" and the "hypo" - people, its part of our daily life.
On the other hand Im not really fearing "hormonal manipulation" - other options like the psychopharmacons do a much safer job (from the perspective of efficacy and quality of control). Why thyreoid hormons if a nice pill with diazepam does it ?
But lets look more on the positive side: if we manage to understand why people do feel bad or good we could help them. Just add some hormones and people have improved mental functions ... interesting but dangerous game!

gejala stroke said at August 29, 2016 8:18 PM:

Gejala Storoke ringan dan cara menanganinya secara alami harus diperhatikan selalu secara serius , karena saat ini kasus penyakit stroke banyak terjadi dikalangan masyarakat dari mulai stroke ringan hingga stroke berat.
Meski yang dialami masih gejala stroke ringan tapi penanganannya harus secara tepat karena bisa berakibat fatal jika tidak diatasi dengan obat stroke yang ampuh. Sebelum kita membahas lebih lanjut mengenai pengobatan stroke, maka kita harus mempelajari dulu tentang apa itu penyakit stroke, penyebab penyakit stroke, gejala stroke,
serta bahaya apa yang bisa muncul? Setelah itu baru kita bisa memilih obat stroke yang tepat yang akan kita gunakan.

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