From: hound23x@gmail.com   
      
   Media overstates dementia benefits of Mediterranean diet   
      
   Behind the Headlines   
      
   Monday February 23 2015   
      
      
   The Mediterranean diet is similar to the UK's recommended "Eatwell plate"   
   The Mediterranean diet is tasty and healthy   
   "New diet to fight dementia," claims the Sunday Express, while The Independent   
   reports: "Mediterranean diet could help beat dementia".   
   Despite the media focus on the Mediterranean diet, this was only a small part   
   of a review which aimed to discover whether some modifiable risk factors (such   
   as high cholesterol or high blood pressure) were linked to the risk of   
   developing dementia in    
   people with existing mild cognitive problems.   
   The review found collated relevant studies, covering a wide variety of   
   potential risk factors, finding the most evidence around diabetes, high blood   
   pressure and mental health.   
   Researchers found that the evidence suggested diabetes increased the risk of   
   "conversion" from mild cognitive impairment to dementia. However, this   
   increased risk was not adjusted for other potential confounding factors such   
   as physical activity or    
   smoking - which could influence the results.   
   The researchers found a single study assessing the Mediterranean diet in   
   people with one type of mild cognitive impairment (particular problems   
   remembering specific events). It found that the Mediterranean diet was   
   associated with a reduced risk of    
   developing Alzheimer's among people with this type of mild cognitive   
   impairment. However, it does not provide strong enough evidence to suggest   
   that following the Mediterranean diet will definitely reduce the risk of a   
   person with mild cognitive    
   impairment developing dementia.   
   While this review is helpful, there is still a lot to be learned about risk   
   factors for dementia and how to reduce risk.   
   Where did the story come from?   
      
   The study was carried out by researchers from University College London and   
   Johns Hopkins Bayview Medical Center, Baltimore, US. One of the authors   
   reported receiving financial support from various sources including the   
   National Institute on Aging and    
   National Institute of Mental Health, as well as various pharmaceutical   
   companies. The other authors reported no financial relationships with   
   commercial bodies.   
   The study was published in the peer-reviewed medical journal the American   
   Journal of Psychiatry.   
   The main body of The Independent's article is quite representative of this   
   study, focusing on links with diabetes and mental health symptoms and risk of   
   dementia. However, the choice to focus the headline on the Mediterranean diet   
   is quite confusing and    
   misleading. The Mediterranean diet was not the main focus of the review or its   
   findings, and the evidence on it in the review comes from only one study. The   
   Express' coverage was similarly skewed in focusing on diet.   
   What kind of research was this?   
      
   This was a systematic review that looked at which modifiable behaviours are   
   associated with the development of dementia in people who have mild cognitive   
   impairment (MCI).   
   The researchers say that recent public health campaigns have increased the   
   recognition and diagnosis of MCI - described as a state between normal ageing   
   and dementia. MCI is where someone (or a relative or doctor) has concerns   
   about their cognitive    
   symptoms, but they have normal functional activities and do not meet a   
   diagnosis of dementia.   
   Almost half of people with MCI are reported to develop dementia within the   
   following three years. However, ways to prevent the onset of dementia are   
   unclear. The researchers had conducted a previous review of randomised   
   controlled trials investigating    
   treatments for MCI, but they found no consistent evidence that any of the   
   treatments reduced the person's cognitive decline, or the risk of the person   
   developing dementia.   
   In the absence of trial evidence, they aimed next to look at observational   
   studies to get an idea of which modifiable risk factors (such as different   
   lifestyle choices) are associated with an increased or reduced risk of   
   dementia. This may help to    
   identify ways people might be able to reduce the risk of dementia developing.    
   A systematic review is the best way of gathering all the available evidence on   
   a particular question. However, such reviews are always going to be inherently   
   limited by the quality of the underlying studies identified.   
   What did the research involve?   
      
   The researchers searched two literature databases (PubMed and Web of   
   Knowledge) using relevant search terms to identify published longitudinal   
   studies of "potentially modifiable risk factors" in people with MCI that   
   looked at dementia outcomes.   
   The researchers defined MCI as cognitive impairment identified from objective   
   neuropsychological tests, in the absence of dementia or significant functional   
   impairment. Dementia outcomes were dementia of any cause, or Alzheimer's   
   dementia specifically.   
   They assessed the quality of identified studies, specifically looking for   
   studies which recruited a representative sample of the general older   
   population, had followed at least 70% of the included participants for at   
   least one year, and used objective    
   assessment methods for diagnosing MCI and dementia.   
   They also graded the quality of evidence supporting each of their conclusions   
   as follows:   
   grade 1 evidence: consistent evidence from higher-quality studies   
   grade 2 evidence: evidence from a single higher-quality study or consistent   
   evidence from other studies   
   inconsistent evidence: described as "troublingly inconsistent"   
   What were the basic results?   
      
   The search identified 62 relevant studies, nine of which were considered   
   high-quality. 30 of these studies were pooled in meta-analysis. The studies   
   looked at the following risk factors in people with MCI, as follows:   
   Diabetes   
   The pooled results of seven of 10 studies (grade 2 evidence) found people with   
   MCI who had diabetes were at increased risk of developing dementia during   
   follow-up compared to those without diabetes (unadjusted odds ratio (OR) 1.65,   
   with a 95% confidence    
   interval (CI) of 1.12 to 2.43).     
   High blood pressure   
   The pooled results of seven of 11 studies (grade 2 evidence) did not find that   
   this was associated with significantly increased odds of dementia (OR 1.19,   
   95% CI 0.81 to 1.73).   
   High cholesterol   
   Two studies (grade 2 evidence) found high cholesterol did not predict   
   development of dementia (OR 0.92, 95% CI 0.50 to 1.68).   
   Smoking   
      
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