Cognitive improvement in mild to moderate Alzheimer's dementia after treatment with the acetylcholine precursor choline alfoscerate: a multicenter, double-blind, randomized, placebo-controlled trial

BACKGROUND

Parallel with the development of hypotheses regarding cholinergic involvement in geriatric memory dysfunction, the first attempts to treat patients with Alzheimer's disease (AD) involved the cholinergic-precursor loading approach. Despite encouraging early results, well-controlled clinical trials did not confirm a clinical utility of cholinergic precursors such as choline and lecithin (phosphatidylcholine) in AD.

OBJECTIVE

This study assessed the efficacy and tolerability of the cholinergic precursor choline alfoscerate (CA) in the treatment of cognitive impairment due to mild to moderate AD.

METHODS

In this multicenter, double-blind, randomized, placebo-controlled trial, patients affected by mild to moderate dementia of the Alzheimer type were treated with CA (400-mg capsules) or placebo capsules, 3 times daily, for 180 days. Efficacy outcome measures that were assessed at the beginning of the investigation and after 90 and 180 days of treatment included scores of the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog), the Mini-Mental State Examination (MMSE), the Global Deterioration Scale (GDS), the Alzheimer's Disease Assessment Scale-Behavioral Subscale (ADAS-Behav), all items of the Alzheimer's Disease Assessment Scale (ADAS-Total), and the Clinical Global Impression (CGI) scale. The Global Improvement Scale (GIS) score was assessed after 90 and 180 days of treatment.

RESULTS

A total of 261 patients (132 in the CA group, 129 in the placebo group) were enrolled in the study. The mean (SD) age in the CA group was 72.2(7.5) years (range, 60-80 years), and in the placebo group it was 71.7 (7.4) years(range, 60-80 years). The CA group comprised 105 women and 27 men; the placebo group, 94 women and 35 men. The mean decrease in ADAS-Cog score in patients treated with CA was 2.42 points after 90 days of treatment and 3.20 points at the end of the study (day 180) (P < 0.001 vs baseline for both), whereas in patients receiving placebo the mean increase in ADAS-Cog score was 0.36 point <1 after 90 days of treatment and 2.90 points after 180 days of treatment(P < 0.001 vs baseline). In the CA group, all other assessed parameters (MMSE,GDS, ADAS-Behav, ADAS-Total, and CGI) consistently improved after 90 and 180 days versus baseline, whereas in the placebo group they remained unchanged or worsened. Statistically significant differences were observed between treatments after 90 and 180 days in ADAS-Cog, MMSE, GDS, ADAS-Total, and CGI scores and after 180 days of treatment in ADAS-Behav and GIS scores.

CONCLUSION

The results of this study suggest the clinical usefulness and tolerability of CA in the treatment of the cognitive symptoms of dementia disorders of the Alzheimer type.

Polarized function of thick ascending limbs of Henle cells in osmoregulation

BACKGROUND

Organic osmolytes are necessary for osmoregulation in mammalian kidney. Since renal epithelial cells in many cases possess specific mechanisms both for uptake and osmotically regulated release, we investigated their localization in polarized cells.

METHODS

An immortalized epithelial cell line derived from the thick ascending limb of Henle's loop (TALH) was used to examine the transport characteristics of the apical and basolateral plasma membranes for osmotic regulation of organic osmolytes. Cells were cultured on filters in a two-compartment chamber.

RESULTS

In culture under hypertonic conditions the TALH cells accumulated in the following balance: sorbitoverline> betaine = myo-inositoverline> glycerophosphoryl choline (GPC). When extracellular osmolarity was decreased, then sorbitol was released on the apical side, whereas betaine and myo-inositol efflux occurred on the basolateral side. GPC release showed no preference of either side. Taurine did not seem to be necessary for osmoregulation under these conditions. Osmotically regulated myo-inositol and betaine uptake was located on the apical side, and choline uptake took place on both sides equally.

CONCLUSION

These results show that in renal epithelial cells, both osmotically induced release and the uptake of organic osmolytes are divided between the apical and the basolateral sides. This might be important for volume regulation.

Intrarenal distribution of organic osmolytes in human kidney

The distribution pattern of renal organic osmolytes in surgically explanted human kidneys was investigated and compared with that of untreated Sprague-Dawley rats (Uosmo = 1186 mosmol/kg H2O). Sorbitol, myo-inositol, glycerophosphorylcholine and betaine were measured by liquid chromatography (HPLC) in homogenates of five different kidney zones from the cortex towards the papillary tip. All four organic osmolytes were detected as in human as in rat kidney. The expected increase from the inner medulla to the papillary tip for sorbitol and betaine, and from the outer medulla to the papilla for glycerophosphorylcholine, was observed in rats, but not in explanted human kidney. An inverse distribution pattern was observed with decreasing tissue contents from the inner and outer medulla to the papillary tip for all organic osmolytes and urea. This intrarenal osmolyte profile is in accordance with that observed during water and lithium diuresis in rats. Therefore it can be assumed that a loss of renal medullary osmolytes during the intra-operative treatment of patients led to the observed osmolyte pattern. We conclude that organic osmolytes are involved in renal medullary osmoadaptation of humans.

Determination of plasma choline by high-performance liquid chromatography with a postcolumn enzyme reactor and electrochemical detection

A method for the determination of choline in human plasma is described, involving rapid purification of plasma samples and analysis by high-performance liquid chromatography using an on-column enzyme reactor with electrochemical detection. The linearity of the method was tested at choline levels from 3.5 to 28.6 microM in plasma. The recovery was 86% and was independent of the analyte concentration. The inter-assay precision (as coefficient of variation) and accuracy (as the deviation of the concentration found from the theoretical value) were always below 12% in the whole concentration range. The method was applied to the determination of plasma choline levels in eight healthy volunteers after intramuscular administration of L-alpha-glycerophosphorylcholine (1 g) or a placebo. Mean plasma choline levels in the placebo group ranged from 10.6 to 12.0 microM. After drug administration, the plasma choline level reached 35.1 microM in 30 min, then decreased gradually. Plasma choline levels became comparable in the treated and placebo groups 6-8 h after administration.

Absorption, tissue distribution and excretion of radiolabelled compounds in rats after administration of [14C]-L-alpha-glycerylphosphorylcholine

The kinetics and metabolism of L-alpha-glycerylphosphoryl-choline (alpha-GPC) were investigated in male and female rats after i.v. (10 mg/kg) and oral doses (100-300 mg/kg). alpha-GPC was labelled with [14C]-glycerol ([14G]-GPC) or [14C]-choline ([14C]-GPC). Different kinetic and metabolic profiles were observed after i.v. and oral administration. It is assumed that alpha-GPC is hydrolyzed by phosphodiesterases in the gut mucosa. The different labelled metabolites have different kinetic properties of absorption, distribution and clearance, leading to different blood concentration-time curves of total radioactivity. Both labelled compounds gave a wide distribution of radioactivity, particularly concentrated in the liver, kidney, lung and spleen compared to blood. Brain concentrations of [14C]-GPC were comparable to ([14G]-GPC) or lower than ([14C]-GPC) total blood radioactivity. The metabolite profile in the perfused brain showed a small amount of choline and two unknown metabolites, probably the same as in blood. In addition, choline was incorporated into brain phospholipids in increasing amounts within 24 h of dosing. In all cases renal and fecal excretion of radioactivity was low and comparable for [14G]-GPC and [14C]-GPC. Mostly the administered radioactivity was exhaled as 14CO2, this degradation being faster and more pronounced for the glycerol-labelled metabolites than for the choline-labelled metabolites for both routes of administration. In all cases the results were the same for male and female rats.

Organic solute profiles and transport in the rat renal medulla

Renal inner medullary cells accumulate high concentrations of organic solutes. Sorbitol and glycerophosphorylcholine accumulation (concentration) increase progressively from the outer medulla to the papillary tip. Inositol accumulation is the reverse; its concentration decreases from the outer medulla to the papillary tip. Diabetes mellitus (1 week) increases sorbitol at all levels of the inner medulla, decreases glycerophosphorylcholine and has little effect on inositol. Thin slices of the inner medulla incubated in vitro concentrate inositol and choline from the medium. Although the inner medullary cells are permeable to sorbitol, membrane transport appears to play no role in its accumulation.