In the past, cognitive decline was believed to be unavoidable with the passage of time. Attributed simply to 'old age', many families watched helplessly as their loved ones' minds slipped away. Recent research, however, has challenged the idea that dementia and cognitive decline are a natural result of growing old, and has suggested that, to some extent, it may even be preventable.
* Toxic metal build-up causes oxidative damage that damages brain tissue, leading to dementia (Med Hypoth, 1999; 53: 3, 175-6; Lancet, 1997; 349: 1189-90). Patients with Alzheimer's disease are more likely to have spent a lifetime consuming foods high in aluminium-containing preservatives (some grain products, ready-made desserts, cheese, chocolate pudding, chocolate beverages, salt and some chewing gum) (Age Ageing, 1999; 28: 205-9). A lifetime's use of aluminium-containing antiperspirants is also a risk factor (J Clin Epidemiol, 1990; 43: 35-44) as is aluminium in our water supply. In areas with a high aluminium content in the drinking water, the incidence of Alzheimer's can increase by as much as 46 per cent over the usual rate (Lancet, 1991; 338: 390).
* Mercury is a similarly potent neurotoxin. US studies suggest that people with Alzheimer's have abnormally high levels of mercury in their brain (Neurotoxicology, 1988; 9: 1-8; Brain Res, 1990; 533: 125-31). The most common source of mercury toxicity is dental amalgam fillings. Have these removed, if you can, and avoid seafoods that are likely to be contaminated (see below). Consume foods high in selenium (Brazil nuts, turkey, chicken, sole, flounder, wheatgerm, brown rice and oatmeal) or take selenium supplements.
* Protect your liver. A poorly functioning liver can affect your immunity. Limiting alcohol and your intake of saturated fats can help. A high-fibre diet will aid the elimination of toxins, while sulphur-rich foods such as onions and garlic will promote liver health.
* Atherosclerotic plaque can lead to poor circulation and oxygen deprivation - which are both risk factors for dementia (Int J Geriatr Psychiatry, 1999; 14: 1050-61). In one study, individuals who had an inherited tendency for dementia had a 20-fold greater risk of developing Alzheimer's if they also had atherosclerosis (Haemostasis, 1998; 28: 167-73).
To counter this increased risk, keep blood vessels flexible by taking vitamin C and bioflavonoids, at a ratio of 0.7 units of bioflavonoids for each unit of vitamin C (J Am Diet Assoc, 1994; 94: 779-81).
* Ginkgo biloba extract (GBE) increases circulation to the brain and organs, and protects nerve cells from brief periods of oxygen deprivation. GBE can also enhance nerve receptor and neurotransmitter function (N Carolina Med J, 2000; 61: 393-5). Aim to take 120-240 mg daily.
* Quit smoking. Research shows that this habit can double your risk of dementia (Lancet, 1998; 351: 1840-3).
* Add fish to your diet. Eating fish or some other type of seafood at least once a week has been shown to reduce the risk of developing dementia and Alzheimer's disease by 34 and 31 per cent, respectively (BMJ, 2002; 325: 932-3). The downside is that many types of fish contain mercury. To be safe, limit your consumption of high-risk fish (shark and swordfish) to no more than one meal per month. Smaller, less polluted fish and seafood - such as shrimp, pollock, salmon, cod, catfish, clams, flatfish, crabs and scallops - can be consumed more often.
* Investigate DHEA (dehydroepiandrosterone) supplements. Several studies have found that people with Alzheimer's have lower levels of the adrenal hormone DHEA than those without Alzheimer's (Biol Psychiatry, 2000; 47: 161-3; Biol Psychiatry, 1991; 30: 684- 90). A dose of 100 mg/day may be helpful.