Alcohol, Hormones and Neurotransmitters

Alcohol and Hormones

Cortisol

Cortisol is a “stress hormone” released from the adrenal gland. It increases the blood glucose levels and stimulates water retention.

Acute alcohol intoxication that brings blood alcohol concentrations above 0.1 grams alcohol/100 mL of blood (for example, from about 5 drinks in one hour by a 160 lbs man) increases the blood cortisol levels ^[1]. The extent of the increase may be genetically predisposed and may be attenuated by alcohol tolerance ^[1,2,3].

Heavy, chronic alcohol drinking increases the blood cortisol levels, just like stress does ^[1,2,4]. Elevated cortisol levels increase the risk of infections, mood changes ^[5], high blood pressure ^[6] and premature aging ^[1].

During alcohol withdrawal in a chronic drinker, cortisol levels often temporarily increase and cause anxiety ^[5,7].

Rarely, alcoholism causes alcohol-induced pseudo-Cushing syndrome with permanently increased blood cortisol levels ^[8]. Symptoms include collection of fat in the trunk and face (“moon face”), excessive body hair in women, blue-red striae, osteoporosis, high blood pressure and muscle weakness ^[9]. Symptoms disappear within 1-3 weeks after alcohol withdrawal ^[10].

Aldosterone

The hormone aldosterone is secreted from the adrenal gland. It promotes sodium and water retention and helps to maintain blood pressure.

Alcohol intoxication stimulates aldosterone secretion ^[11]. During alcohol withdrawal, aldosterone levels start to drop and normalize ^[12]. According to one 1983 study, the blood aldosterone levels are not associated with increased blood pressure during alcohol intoxication or withdrawal ^[6].

Epinephrine (Adrenaline)

The hormone adrenaline is secreted from the adrenal gland. It promotes alertness and “fight response”, increases blood glucose levels and helps to maintain blood pressure.

In one study, 1-2 alcoholic drinks did not increase the blood epinephrine (adrenaline) levels ^[13], but chronic alcohol drinking can increases the levels ^[14].

According to one 1984 study, ingestion of moderate amount of alcohol results in increase of blood epinephrine levels and blood pressure in healthy young men ^[14].

During alcohol withdrawal the blood levels of epinephrine may temporarily increase and correlate with symptoms severity ^[15].

Antidiuretic Hormone (ADH) or Vasopressin

The antidiuretic hormone (ADH) is secreted from the pituitary gland; it inhibits water excretion in the kidneys.

In one study, alcohol blocked the secretion of antidiuretic hormone (ADH) within the first 3 hours after starting drinking and increased urine excretion (diuresis), but within 6-12 hours after starting drinking it stimulated ADH secretion and decreased urine excretion ^[16-p.134]. Considering this, alcohol probably does not lead to significant dehydration ^[16-p.134]. In one 1978 study in people after 50 years of age, intravenous alcohol infusion has blocked ADH secretion and increased urine excretion for only 30 minutes after the onset of infusion despite continuing rise of the blood alcohol concentration ^[17].

In dehydrated individuals, drinking beverages containing up to 4 vol% alcohol does not aggravate dehydration; it can actually help in rehydration ^[18].

In chronic alcoholics, basal blood ADH levels may be low and may remain low even after alcohol withdrawal ^[20].

Rarely, alcohol withdrawal may induce the secretion of ADH (syndrome of inappropriate ADH secretion or SIADH) and thus water retention and hyponatremia ^[21].

Insulin

The hormone insulin is secreted by the pancreas. It promotes the movement of glucose from the blood into the body cells.

In healthy individuals, moderate alcohol drinking may increases insulin sensitivity and decrease the risk of diabetes type 2 ^{[22,23,24,25]}.

Alcohol enhances glucose-induced secretion of insulin and may thus cause reactive hypoglycemia ^[11].

DHEA (Dehydroepiandrosterone)

DHEA is a hormone produced by the adrenal gland. It serves as a precursor of male and female sex hormones.

Acute alcohol intoxication increases the blood levels of DHEA in women, but not in men ^[26].

Testosterone

Testosterone is a male sex hormone produced in testes. It is responsible for maintaining libido and contributes to muscle strength and bone density, among other.

In one 2003 study, consumption of moderate amount of alcohol (0.5 g alcohol/kg body weight or 2-3 drinks by a 160 lbs man) resulted in an increase of blood testosterone levels in men ^[27].

In men, chronic heavy drinking may decrease the testosterone levels, which may result in breast enlargement, reduced facial and chest hair, shrinkage of testicles, decreased sperm production and erectile dysfunction ^[28,29].

During hangover and alcohol withdrawal, blood testosterone levels may be decreased ^[11]. Low testosterone levels during alcohol withdrawal may be responsible for indecision, excessive worrying, lassitude and fatigue ^[30]. Low testosterone levels in chronic alcoholics may slowly return to normal after alcohol withdrawal ^[30].

In women, acute alcohol intoxication increases testosterone levels ^[26].

Estradiol and Progesterone

In women before menopause, moderate alcohol consumption (0.3-1 g/kg body mass or 2-5 drinks by a 160 lbs woman) is associated with lower blood progesterone levels ^[32].

In women after menopause, moderate drinking (up to 7 drinks/week) may increase the blood estradiol levels ^[31,32].

Growth Hormone

The growth hormone is secreted from the pituitary gland. It promotes bone growth.

Both acute and chronic drinking are associated with decreased blood growth hormone levels ^[39].

Alcohol and Neurotransmitters

Neurotransmitters are substances that conduct signals between nerves.

Enkephalins and Endorfins

Enkephalins and endorfins are endogenous opioids associated with positive alcohol reinforcement ^[38]. Alcohol stimulates the release of endogenous opioids in the brain thus causing the same effect as opioid drugs (morphine): the feeling of well being, euphoria and pain relief and, in lager amount, nausea, drowsiness, poor appetite, depression of respiration ^[41]. The response of endogenous opioids to alcohol (the feeling of well being) is genetically determined and is greater in individuals with family history of alcoholism ^[41].

Serotonin

Serotonin improves mood, induces sleep, induces satiety ^[42], stimulates intestinal motility, decreases blood coagulation and clot formation, stimulates glycogenolysis and increases blood glucose levels ^[43]. Low serotonin levels can cause depression in sensitive individuals ^[44], fatigue, uncontrolled anger, craving for sugar, obesity, low libido and nausea. Foods high in carbohydrates increase brain serotonin levels ^[46,47], but foods high in the amino acid tryptophan (a precursor of serotonin) and serotonin do not ^[48].

Acute and chronic drinking increase the release of serotonin in the brain ^[45]. Serotonin mediates rewarding effect of alcohol ^[45]. Chronic alcoholics have lower levels of serotonin in the brain ^[45,46]. Serotonin levels fall during alcohol withdrawal and remain low for more than 2 weeks, which may explain anxiety during withdrawal ^[45,49]. Alcohol craving is probably not related to serotonin levels ^[49].

Dopamine

Dopamine stimulates rewarding behavior. For example, an image of an alcoholic beverage, its smell or even thinking about it stimulates the release of dopamine in your brain, what encourage you to start to drink ^[37]. Dopamine is also involved in positive reinforcement (the expectancy of pleasant alcohol effects stimulates drinking) and negative reinforcement (the expectancy of unpleasant feelings after alcohol withdrawal stimulates drinking) ^[35,38].

Alcohol stimulate the release of dopamine in the brain ^[37]. Craving for alcohol in chronic alcoholics is mediated by dopamine ^[37].

Other Neurotransmitters

Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter. Alcohol enhances the inhibitory effect of GABA and thus causes sedation and impairs memory ^[5,33,34,35].

Glycine is an inhibitory neurotransmitter. Alcohol increases the inhibitory effects of glycine in the spinal cord and brain-stem ^[35].

Adenosine is an inhibitory neurotransmitter. Alcohol enhances the inhibitory effect of adenosine and can thus cause sedation ^[35].

Glutamate is a stimulating neurotransmitter. Alcohol suppresses the stimulating effect of glutamate and can thus cause sedation and impaired memory ^[5,33,34,35].

Norepinephrine activity in the brain is increased in acute alcohol intoxication in both healthy individuals and chronic alcoholics ^[36] and during alcohol withdrawal ^[19,40].

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