A method of treating a subject and preventing in a subject age-dependent basal forebrain cholinergic dysfunction related neurodegenerative disorders, comprising: administering a lipid composition comprising a therapeutically effective amount of highly enriched 1-acyl chains/2-docosahexaenoic acid containing molecular species of highly pure phospholipids to promote survival of aged basal forebrain cholinergic neurons, the phospholipids selected from the group consisting of phosphatidylserine, phosphatidylethanolamine, and phosphatidyl-monomethylethanolamine. A composition for treating a subject and preventing in a subject age-dependent basal forebrain cholinergic dysfunction related neurodegenerative disorders, the composition comprising: a lipid composition comprising: a therapeutically effective amount of highly enriched 1-acyl chains/2-docosahexaenoic acid containing molecular species of highly pure phospholipids to promote survival of aged basal forebrain cholinergic neurons, the phospholipids selected from the group consisting of phosphatidylserine, phosphatidylethanolamine, and phosphatidyl-monomethylethanolamine. A process for preparing a lipid composition comprising a therapeutically amount of natural source-based highly enriched 1-acyl chains/2-docosahexaenoic acid containing molecular species of highly pure phosphatidylserine to promote survival of aged basal forebrain cholinergic neurons; the process comprising: purifying a natural source-based phosphatidylcholine by silica chromatography; obtaining a related lysophosphatidylserine species by phospholipase A2 catalysis of transphosphatidylated natural source-based phosphatidylserine species; acylating the lysophosphatidylserine species with natural docosahexaenoic acid to form 1-acyl chains/2-docosahexaenoic acid containing phosphatidylserine species; and purifying the 1-acyl cgains/2-docosahexaenoic acid containing phosphatidylserine species by silica chromatography.