Higher levels of mercury in brain not linked with increased risk of Alzheimer’s disease, study shows

Eating seafood such as fish, lobster and crab is often said to have health benefits, but its contamination by the neurotoxin, mercury, is a cause of increasing concern.

This investigation, published today in JAMA Network Journals, analysed the levels of mercury in the brains of several older people who were taking part in a study on lifestyle and ageing.

The researchers, from Rush University Medical Centre in Chicago, found that eating one to three meals a week containing seafood was associated with less signs ofAlzheimer’s disease. The researchers also found that eating a lots of seafood was associated with high levels of mercury in the brain, however this was not associated with the signs of Alzheimer’s disease. The researchers believe that the presence of another nutrient found in fish called selenium may lessen the toxic effects of mercury.

Responding to this, Dr James Pickett, Head of Research at Alzheimer's Society, said:

“Eating seafood has often been associated with improved memory and better health – but the research into whether eating fish can prevent or delay dementia has produced conflicting results. 

“The fact that the presence of mercury in the brain – which has been linked to eating a lot of seafood – was not associated with signs of Alzheimer’s is encouraging news for fish lovers. However, given the relatively small size of this study, these findings are by no means conclusive. We look forward to seeing more results in this area of research.”

“We know that Alzheimer’s disease and other forms of dementia are caused by a complex interplay of genetics, lifestyle and environment. What’s interesting about this study is that people with different genetics saw different benefits from a diet rich in seafood. This may give us some clue as to why eating seafood could benefit some people over others – but we need further work to find out if this is the case."