Qing LiFeng Wang

The concept of the Mediterranean diet （ MeDi ） is a modern nutritional recommendation originally inspired by the traditional dietary patterns of Greece， Southern Italy， Spain. The principal aspects of MeDi include proportionally high consumption of olive oil， legumes， fruits， vegetable and unrefined cereals， moderate consumption of fish， low to moderate consumption of dairy products （mostly as cheese and yogurt） and wine， and low consumption of red meat （Willett et al.， 1995）.

MeDi benefits long-term health and wellbeing. The MeDi has been associated with reduced risk of a wide range age-related condition such as stroke， Type 1 diabetes， dementia， cardiovascular disease， and all-cause mortality. A Estruch et al.’（2013） study found among persons at a high cardiovascular risk， a MeDi supplemented with extra virgin olive oil or nuts reduced about 30% the incidence of major cardiovascular events. A meta-analysis showed that adherence to MeDi can significantly decrease the incidence of overall mortality， cardiovascular disease， cancer and neurodegenerative disease such as Parkinson’s disease （PD）， Alzheimer’s disease （AD） ， Mild cognitive impairment （MCI） （Sofi et al.， 2010）.

MeDi benefits long-term cognitive health. Here， I focus on the evidence for benefit of the MeDi on cognitive health. Cognition is a combination of mental processes that include the ability to learn new things， intuition， language， judgement， remember. When cognition is impaired， a persons has trouble with these processes that begins to effect the things he or she can do in everyday life. The lack of cognition from mild cognitive decline to dementia， can have profound and negative implication for individuals health and wellbeing.

The MeDi may exert its effects on cognition health through multiple biological mechanisms. First， cerebrovascular disease is possible mechanism of relationship between MeDi and AD. An investigation into the MeDi and MRI infarcts found that large vessel disease could be in the biological pathway between MeDi and AD （Scarmeas et al.， 2001） . reduced risk of metabolic syndrome has been associated with MCI， dementia or AD （Raffaitin et al.， 2009， 2011）. Higher adherence to MeDi may cause lower risk of metabolic syndrome and its components （Kastorini et al.， 2011）. Second， oxidative stress increases with age and results in oxidative damage – a state often observed in the brain of patients with AD. Typical components of the MeDi （namely fruit， vegetable， wine， virgin olive oil） are rich in antioxidants such as vitamin C and E， carotenoids and flavonoids. Decreased oxidative stress found in people adhering to a MeDi could partially explain their lowered risk for dementia （Dai et al.， 2008）. Third， inflammatory processes has been suggested for Alzheimer pathogenesis. High-sensitivity C-reactive protein， a nonspecific marker of inflammation have been associated with increased the risk for cognitive decline， AD and vascular dementia， whereas， better adherence to MeDi has involved lower levels of hsCRP （Gu et al.， 2010）. However， the favorable association between MeDi and AD did not seen to be mediated by hsCRP （ibid.） results from investigation studies.

In a 2006 study of more than 2000 dementia-free adults ages 65 and older， Scarmeas et al. revealed persons who consumed a MeDi regularly were 39-40 less likely to develop AD over the next 4 years. In 2007， they investigated the relationship between adherence to MeDi and mortality in AD patients. This result showed higher adherence to MeDi is associated with lower mortality in AD. Finally， Scarmeas et al. extended the participants to cognitively normal and MCI patients. This finding suggested that higher adherence to MeDi is associated a borderline

Reduction in the risk of conversion from MCI to AD.

A prospective study （3C study） examined the association of a MeDi with change in cognitive performance and risk for dementia in aged 65 years or over French person. This study found higher adherence to MeDi was significantly associated with better performance in global cognition and episodic memory ， especially in individuals who remained free from dementia over 5 years. However， no association found between the MeDi and dementia risk. These results suggested the MeDi exert a beneficial effect early in the prodromal phase of dementia （Feart et el.， 2009）.

The meta-analysis mentioned above has combined results from WHICAP and 3C study. A two-point increase in the MeDi adherence scale has associated with 13% reduction in the incidence of neurodegenerative disease including dementia （sofi et al.， 2010）.

In conclusion， published studies have provided scientific evidence to argue that greater adhence to the MeDi is associated with slower cognitive decline and lower risk of developing AD. Further studies showed clarify the mechanisms by which the MeDi may protect against dementia and prove the MeDi may exert beneficial prosperity at early cognition decline stages.

Reference

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