Alpha glycerylphosphorylcholine (choline alfoscerate, alpha-GPC, glycerophosphocholine) is a natural choline compound that is often used as a nootropic dietary supplement to enhance memory and cognition . It is made of choline, glycerol and phosphate and it rapidly delivers choline to the brain across the blood-brain barrier and is a biosynthetic precursor of the acetylcholine neurotransmitter .
Improved Cognition with Alpha-GPC
Results of studies in animals  with (scopolamine-induced) amnesia indicate that alpha glycerylphosphorylcholine, when administered orally, reverses amnesia. Dr. Corrado Lacomba and others  investigated the effects of L-alpha glycerylphosphorylcholine on the EEG (ElectroEncephaloGraphic) power spectrum in rats. Oral administration of alpha-GPC (100–300–600 mg/kg) induced a significant decrease in delta waves (usually associated with deep sleep and are increased during aging or accelerated cognitive deterioration) and a significant increase in beta waves (normal waking consciousness) . Cognition enhancing effect was probably correlated with alpha-GPC’s stimulatory effect on brain acetylcholine (a neurotransmitter that increases the release of growth hormone ) release . Acetylcholine has been shown to increase at the onset of the standard sustained attention task .
Well controlled clinical trials are reporting that glycerophosphocholine improves attention and word recalling in young, improves cognition, mood and behaviour in people with memory decline, aids in recovery from brain trauma, can be used to boost growth hormone, and can partially revitalize aging brain. 
In 2001, Parnetti  analyzed 10 clinical trials that included 1,570 patients with dementia. Her meta-analysis concluded glycerophosphocholine is useful against cognitive decline related to dementia .
A very recent study  designed to measure the acute effects of Alpha-GPC supplementation in comparison to caffeine or placebo on mood, cognitive function, and physiological performance reported no statistically significant beneficial effect on measures of mood, cognitive function, or physiological performance. However, for some physical and mental performance tasks alpha-GPC has showed slight improvements. The draw back of this study is large individual variability between subjects.
Growth Hormone Enhancing Properties of Alpha-GPC
Glycerophosphocholine may also be used as a hormone secretogauge. There is a growing body of research that assess the effect of alpha-GPC on growth hormone secretion by the pituitary gland. As you might have guessed its effects are mostly evident in older adults.  However, Kawumara and others  tested glycerophosphocholine on eight healthy young males and noted a significant increase in plasma growth hormone 60 minutes after ingestion.
Alpha-GPC also supports other transmitter systems such as dopamine, norepinephrine, and gamma-aminobutyric acid (GABA) (in vitro and in vivo evidence) .
Dosage and Safety of Glycerylphosphorylcholine
Usual dosage used in trials was 1,2 grams per day. There were more than 4,000 patients who received oral GPC in clinical trials, not one reported to experience an adverse effect serious enough to cause withdrawal from a trial.
(Other common names: Alfa-GPC, Alpha Glycerol Phosphoryl Choline, GPC, GroPCho, L-A-Glyceryl Phosphorylcholine, L-alpha-glycerylphosphorylcholine, Alpha-Glyceryl Phosphoryl Choline, Alpha-Glyceryl Phosphatidylcholine, Choline alphoscerate, Alpha-glycerylphosphorylcholine, Glycerophosphorylcholine, choline alfoscerate)
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