Environmental Risk Factors: Parkinson’s Disease and Alzheimer’s Disease: Part II

There is evidence to suggest that certain types of work may affect risk levels due to occupational exposure to toxins and viruses, or due to the level of physical or mental exercise. What is important to appreciate, higher or lower levels of risk for PD has been described for different professions, but confounders and inconsistent data continue to present. In reference to Alzheimer's disease and profession, no studies on risk are available at this time.


Interestingly, certain food products have been associated with different degrees of PD risk, but further research is required before stating a clear association. Curiously, a higher risk of PD is associated with milk consumption (men only), however, the reason for this is unknown. Moreover, this tendency has not been observed with other dairy products or with calcium or vitamin D consumption. Several prospective studies have indicated that the Mediterranean diet, in general, is associated with slower cognitive decline and reduced risk of AD, however, evidence is insufficient to make specific dietetic recommendations.

Omega 3 fatty acids have been shown to have a neuro-protective effect in PD, nonetheless, the data requires further follow up before a specific dose can be recommended. Diets rich in DHA (a key component of omega 3 fatty acids), combined with antioxidant therapy, reduce amyloid disease and improve cognition in animal models of AD. Furthermore, several epidemiological studies suggest that increased consumption of fish and omega 3 reduce risk of dementia, an area that warrants further research.

No association has been established between consumption of certain vitamins and minerals and the risk of PD or AD, except that PD risk is slightly lower with higher Vitamin E and Niacin consumption. Recently, research has identified that PD risk is slightly higher for individuals with elevated iron consumption.


Nicotine stimulates DA neurons, inhibits alpha-synuclein fibril formation, and lessens symptoms of PD. It may also improve cognitive function by stimulating nicotinic receptors. On the other hand, tobacco use accelerates cerebral atrophy, decrease blood perfusion, increases oxidative stress and is causal for silent infarction and inflammation. Nonetheless, studies have shown that the children of 2 smoking parents have a lower risk of developing PD than children of 2 non-smoking parents. Several randomised control trials have found that nicotine patches have failed to lessen symptoms in patients with PD. In contrast smoking has been associated with a higher risk of developing AD.

Depression and Stress:

Epidemiological studies show that a history of depression and the number of depressive episodes are associated with increased risk of AD, however, the exact mechanism is unknown. Moreover, it has been proposed that depression may be a prodromal phase of the disease.

Oestrogen and Hormone Replacement Therapy:

The DA depletion caused by various toxins is decreased by Beta-Oestradiol, however, has only been proven in in-vitro and animal models. Interestingly, DA depletion is less pronounced in females. Oestrogens have antioxidant properties that stimulate the survival and growth of cholinergic neurons, induce non-amyloidogenic metabolism and increase cholinergic activity. HRT has been associated with a lower risk of PD min some studies, but not the majority. In reference to AD, high levels of oestradiol were associated with a 43 percent increase in the risk of dementia.

If you have any questions regarding this post, please make contact:

Mark Hinchey, Newcastle Naturopath, 601 Glebe Road Adamstown, Newcastle, NSW, Australia

P: 0432234822

E: info@markhincheynaturopathy.com.au

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