First thing to know is that genetics play a massive role. There is a polymorphism known as epoE4 which increases the chances of someone developing a neurodegenerative condition.
Phospholipid Omega 3 – found in krill oil and salmon roe. Phospholipid forms of omega 3, can reach the brain or pass the blood brain barrier with DHA, more readily than normal forms of omega 3, in people who are genetically predisposed to neurogenerative diseases. More information on this here.
Water – as pure as possible, or from a natural form. In the UK, many old properties still have lead pipes. Dehydration is said to be a major cause of cognitive issues in old age.
BDNF – some supplements like lions mane mushroom, increase levels of BDNF which in turn can help ‘neurogenesis’ in some parts of the brain. Cardiovascular exercise can also help do the same.
Avoid Anti Histamines – some research suggests that anti-histamines might cause cognitive problems in the long run.
Creatine – research suggests that creatine has neuroprotective properties. Some suggest it can damage the kidneys but I’m unaware of the research behind this.
Turmeric – maybe – turmeric has been shown to reduce amyloid plaque formation, but recent studies suggest much of the turmeric you can buy, is high in lead. Curcumin might be a better idea, use a small amount daily.
A growing body of evidence indicates that oxidative stress, free radicals, beta amyloid, cerebral deregulation caused by bio-metal toxicity and abnormal inflammatory reactions contribute to the key event in Alzheimer’s disease pathology. Due to various effects of curcumin, such as decreased Beta-amyloid plaques, delayed degradation of neurons, metal-chelation, anti-inflammatory, antioxidant and decreased microglia formation, the overall memory in patients with AD (Alzheimer’s disease) has improvedhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781139/