WE ARE OUR BRAINS - CHAPTER 5
HYPOTHALAMUS, SURVIVAL, HORMONES, EMOTIONS
If a patient would urinate constantly, and the urine tasted sweet, they were diabetic. If it wasn't it was a kidney or brain problem.
DEPRESSION
Is usually a symptom of a physical problem. The spectrum of behaviours associated with depression: withdrawal, less eating, less activity so that your energy can be devoted to curing yourself.
It can also be a symptom of Parkinsonism, schizophrenia, other psychiatric conditions.
But it can also be a condition in its own right.
Genetic factors and womb development program the activity of our stress system for the rest of our lives.
Stress causes nerve cells in the hypothalamus to release corticotropin-releasing-hormone (CRH) to the pituitary gland and brain. The pituitary gland in turn stimulates the adrenal gland to produce cortisol hormone.
If we have too much CRH and cortisol in our bodies, depression results.
Female hormones stimulate the stress axis and male hormones relate it, which is why women are twice as likely to suffer from depression.
Depression may be a developmental disorder of the hypothalamus.
Stress axis = hypothalamus - pituitary - adrenal axis.
Low levels of serotonin and dopamine may trigger the stress axis, which is why SSRIs are used, even though they don't seem to work too well.
SSRI = selective serotonin reuptake inhibitor, increase the amount of serotonin in the brain by inhibiting its reuptake.
They need a couple of weeks to work, during which time there is a great risk of suicide.
They have a placebo effect in 50% of cases.
When you expect a placebo to alleviate your pain, you increase the activity in your PFC, inhibiting the hypothalamus, normalising the stress axis.
Transcranial magnetic stimulation of the cortex also reduces hypothalamus function, and so does cognitive therapy.
Physical activity and light help by stimulating the circadian clock which is smaller in people with depression.
Lack of vitamin D causes depression too, in older people.
OBESITY
80% of the variation in body weight is determined by genetic factors.
Normally the hypothalamus regulates fat by measuring the amount of leptin, a hormone produced by fat tissue.
If there are variations in the leptin gene, or leptin receptor gene, the hypothalamus will conclude that there is no fat - causing extreme obesity.
The brain may not produce alpha MSH: hair pigmentation and appetite inhibition, resulting, in overweight, red haired children who don't enter puberty.
Hormonal disorders or an excess of cortisol may also cause obesity.
Children born in famines, placental malfunctions, HBP in mothers, smoking, obese mothers, overfed babies all may cause obesity.
Lower socioeconomic status and comfort eating too.