Quick Comparison
| ALCAR | Citicoline (CDP-Choline) | |
|---|---|---|
| Half-Life | 4-5 hours | 56-71 hours (sustained release characteristics) |
| Typical Dosage | Standard: 500-2000 mg daily in 1-2 doses. For cognitive support: 1000-2000 mg daily. For neuropathy: 1500-3000 mg daily. Take in the morning — may be mildly stimulating. | Standard: 250-500 mg daily. Clinical studies use 500-2000 mg daily. Take in the morning — mildly stimulating. Cognizin is the most studied form. Can be split into 2 doses. Often combined with racetams to provide the choline needed for enhanced acetylcholine turnover. |
| Administration | Oral (capsules, powder). Well-absorbed on an empty stomach. | Oral (capsules, powder). Cognizin branded form is most studied. Take in the morning. |
| Research Papers | 9 papers | 10 papers |
| Categories |
Mechanism of Action
ALCAR
ALCAR crosses the blood-brain barrier via the organic cation transporter (OCTN2) more effectively than L-carnitine. In neurons, it is hydrolyzed by carnitine acetyltransferase to donate its acetyl group to coenzyme A, forming acetyl-CoA—which can then be used for acetylcholine synthesis via choline acetyltransferase, effectively providing raw material for the memory neurotransmitter. ALCAR also transports long-chain fatty acids across the inner mitochondrial membrane via the carnitine palmitoyltransferase system for beta-oxidation and ATP production. ALCAR activates nerve growth factor (NGF) signaling, possibly through modulation of NGF receptor (TrkA) expression or downstream MAPK/ERK pathways. It has antioxidant properties, reducing lipid peroxidation in mitochondrial membranes and scavenging free radicals. These mechanisms support cognitive function and neuroprotection.
Citicoline (CDP-Choline)
Citicoline (CDP-choline) is hydrolyzed in the gut by alkaline phosphatase to choline and cytidine-5'-monophosphate, which are absorbed separately and reassembled in the brain via the Kennedy pathway. Choline feeds two critical pathways: (1) Acetylcholine synthesis via choline acetyltransferase (ChAT) — the primary memory and learning neurotransmitter acting at muscarinic and nicotinic receptors. (2) Phosphatidylcholine synthesis via CTP:phosphocholine cytidylyltransferase — the structural component of neuronal membranes and synaptic vesicles. Cytidine is dephosphorylated to uridine, converted to UTP, and supports RNA synthesis and CDP-choline formation for synapse formation. Citicoline also activates SIRT1 (possibly via NAD+ modulation) and increases brain norepinephrine and dopamine (mechanism unclear — may enhance synthesis or release). It is the only choline source providing both cholinergic and membrane-building support in one molecule.
Risks & Safety
ALCAR
Common
Nausea, fishy body odor, restlessness, gastrointestinal discomfort.
Serious
May increase agitation in Alzheimer's patients. TMAO production may be a cardiovascular concern with chronic high doses.
Rare
Seizures in susceptible individuals, increased thyroid activity.
Citicoline (CDP-Choline)
Common
Headache (especially with racetams — indicates too much cholinergic stimulation), nausea, diarrhea.
Serious
None documented at standard doses.
Rare
Insomnia, blurred vision.
Full Profiles
ALCAR →
Acetyl-L-Carnitine is an acetylated form of L-Carnitine that crosses the blood-brain barrier more effectively than regular L-Carnitine. In the brain, it donates its acetyl group for acetylcholine synthesis and supports mitochondrial fatty acid oxidation for energy. Used clinically for age-related cognitive decline, depression, and diabetic neuropathy.
Citicoline (CDP-Choline) →
A naturally occurring intermediate in the synthesis of phosphatidylcholine, the primary phospholipid in neuronal cell membranes. Citicoline provides both choline (for acetylcholine and phospholipid synthesis) and cytidine (converted to uridine, supporting RNA and synapse formation). It is prescribed in Europe and Japan for stroke recovery and cognitive decline. Cognizin is the most studied branded form.