Back in 2015 and 2016 some studies found a link between taking medicines that are anticholinergic and cognitive decline and dementia. Some examples of non-prescription anticholinergic medications are Chlor-Trimeton, Benadryl, Tavist, and Dimetapp. During this time a person also contacted me to report that his relative, who had Down's syndrome, had once participated in a study where he received cholinergic therapy, with the result that during the study he functioned better neurologically.
Meanwhile, I read several studies of older people that supported the result of a higher intake of foods with choline and better neurological functioning (e.g. verbal and visual memory).
A recent large study of men over a 4 year period found an association between a higher intake of foods with choline (dietary choline) and better performance on several cognitive tests and lower risk of dementia. The research, which was conducted in Finland, found that the relationship seemed especially strong for a type of choline called phosphatidylcholine. Eggs (specifically the egg yolks) are a primary dietary source of phosphatidylcholine, and indeed, in the study, higher egg intake was associated with better performance on several measures, including verbal fluency, as well as lower risk of dementia.
Choline is an essential nutrient, found in some foods. Its role in the body is complex, but one of its roles is to produce acetylcholine, an important neurotransmitter for memory, mood, muscle control, and other brain and nervous system functions (NIH choline fact sheet). On the other hand, anticholinergic medications block the action of the neurotransmitter acetylcholine (which is involved with learning and memory). Anticholinergic medications include many common drugs, such as some antihistamines, sleeping aids, tricyclic antidepressants, medications to control overactive bladder, and drugs to relieve the symptoms of Parkinson’s disease.
What should one do? First, make sure to eat some foods rich in choline, especially eggs. The researchers themselves say that "consuming an adequate amount of foods high in choline may be an easy, effective, and affordable way to maintain cognitive functioning". Good sources of choline are meat, dairy products, poultry, and eggs - and it appears that eggs (the egg yolks) are especially beneficial. Second, one should also try to avoid non-prescription and prescription medicines known to be anti-cholinergic. For example switch from allergy medicines diphenhydramine or chlorpheniramine (Chlor-Trimeton) to one that isn't anticholinergic. [See list.]
From Science Daily: Dietary choline associates with reduced risk of dementia
A new study by researchers at the University of Eastern Finland is the first to observe that dietary intake of phosphatidylcholine is associated with a reduced risk of dementia. Phosphatidylcholine was also linked to enhanced cognitive performance. The main dietary sources of phosphatidylcholine were eggs and meat. The findings were published in the American Journal of Clinical Nutrition.
Choline is an essential nutrient, usually occurring in food in various compounds. Choline is also necessary for the formation of acetylcholine, which is a neurotransmitter. Earlier studies have linked choline intake with cognitive processing, and adequate choline intake may play a role in the prevention of cognitive decline and Alzheimer's disease. In fact, choline is nowadays used in a multinutrient medical drink intended for the treatment of early Alzheimer's.
The new study now shows that the risk of dementia was 28% lower in men with the highest intake of dietary phosphatidylcholine, when compared to men with the lowest intake. Men with the highest intake of dietary phosphatidylcholine also excelled in tests measuring their memory and linguistic abilities. These findings are significant, considering that more than 50 million people worldwide are suffering from a memory disorder that has led to dementia, and the number is expected to grow as the population ages. Alzheimer's disease is the most common cause of dementia, for which no cure currently exists. The new findings may, therefore, play a vital role in the prevention of dementia. Successful dementia prevention is a sum of many things and in this equation, even small individual factors can have a positive effect on the overall risk, possibly by preventing or delaying the disease onset.
"However, this is just one observational study, and we need further research before any definitive conclusions can be drawn," Maija Ylilauri, a PhD Student at the University of Eastern Finland points out.
The data for the study were derived from the Kuopio Ischaemic Heart Disease Risk Factor Study, KIHD. At the onset of the study in 1984-1989, researchers analysed approximately 2,500 Finnish men aged between 42 and 60 for their dietary and lifestyle habits, and health in general. These data were combined with their hospital records, cause of death records and medication reimbursement records after an average follow-up period of 22 years. In addition, four years after the study onset, approximately 500 men completed tests measuring their memory and cognitive processing. During the follow-up, 337 men developed dementia.
The analyses extensively accounted for other lifestyle and nutrition related factors that could have explained the observed associations. In addition, the APOE4 gene, which predisposes to Alzheimer's disease and is common in the Finnish population, was accounted for, showing no significant impact on the findings. The key sources of phosphatidylcholine in the study population's diet were eggs (39%) and meat (37%).