GM affects the brain

April 2011

GM crops could cause a pandemic of psychiatric disorders. How far-fetched is that?

The scientific wisdom of yesteryear held that a “blood-brain barrier” exists which protects the brain from substances and cells in the blood which would otherwise upset brain function.

There is, indeed a physical blood-brain barrier. But it can be breached. Stress and inflammation can make different areas of the barrier leaky. This allows harmful materials to pass through and disturb the function of associated areas of the brain.

Experiments using laboratory mice are gradually revealing unexpected interactions between the immune system and the brain. Although the exact mechanisms and responses will be somewhat different in humans, the principle is likely to be very much the same.

The picture emerging from the research is that stress, infections, toxins, allergens and obesity all trigger immune system responses. Such responses include the production of antibodies which can bind to cells (including neurones), the activation of immune-system cells, and the release of cell signaling molecules for cell communication. Obesity has a special role in these processes because fat-tissue forms the precursors of cell-signaling molecules.

Immune-system responses in turn trigger inflammation which makes the blood-brain barrier leaky, and potentially exposes the brain cells to all those same immune-system factors. The resulting brain disturbances indicated by the experiments so far include: impaired learning and memory, obsessive-compulsive disorder, depression, anxiety and suspicion, impulsiveness, and development of nervous tics.

In a nutshell, things which make you physically ill can also make you mentally ill.

On a happier note, the opposite is also true, even for infectious micro-organisms. At least one kind of very small bacterium is able to stimulate feelings of well-being. It has been postulated that this microbe is an “old friend” we have co-evolved with for a very long time.

Interestingly, immune responses are not all negative either. They seem to have a role in helping nervous tissue repair, and immune responses triggered by mild stress seem to enhance learning. The concept of useful stress from old microbial friends also fits in with the “hygiene hypothesis” which blames the modern rise in asthma and allergies on lack of early exposure to local 'dirt' to help the immune system mature appropriately.

Where does GM food fit into all of this?

First, GM soya and GM maize form feedstock for the junk food industry. They are a major fuel of the modern obesity epidemic.

Second, GM foods have an increased potential to generate allergens and novel toxins which may cause inflammation. Besides this, all GM crops so far commercialised have inherent systemic pesticides (Bt insecticide and/or glyphosate weedkiller). They may soon include inherent industrial, pharmaceutical and waste chemicals too.

Third, GM material plus novel DNA in the diet has the potential to alter the microbial mix in the gastro-intestinal tract, and to impair its health-promoting qualities, such as protection from inflammation (see GM time-bomb, Microbes in our guts ... a little something to worry about).

The fourth potentially adverse link between GM food and brain-function is the dreaded HGT (horizontal gene transfer) which, to many regulators and scientists, seems to be a taboo subject.

It's now well-known that genes move around in the natural world, and that HGT is a main route for the generation of pathogenic bacteria and viruses. However, natural HGT is an occasional and very restricted event. GM techniques applied to crops are nothing less than a greatly facilitated horizontal gene transfer on a vast scale. As the Institute of Science in Society has described it, genetic transformation “has created highways for gene trafficking in place of narrow by-ways and occasional footpaths that previously existed”.

As if man's gung-ho activity in spreading self-replicating novel DNA throughout his food crops isn't bad enough, we've actually gone one better.

Genetic engineers have been using a common soil bacterium, Agrobacterium tumefaciens, to insert their engineered DNA for them. This bug is used because it's an ideal vector for HGT. Unfortunately it's also persistent. Also unfortunately, its gene transfer activities aren't likely to stop where the biotech engineers want them to.

As far back as 1997, UK government-sponsored research revealed that the novel Agrobacterium used to transform crops is extremely difficult to get rid of in the final product. As a result, the GM plants created using this vector continue to harbour GM Agrobacterium, which continue to be able to genetically transform other plants.

More recent science is uncovering common hotspots were Agrobacterium can genetically transform other forms of life. For example, plant-wound sites caused by pests or agricultural practices have proven a hot-spot for Agrobacterium-mediated genetic transformation of a common fungus. There's no reason to assume this is an unusual case restricted to this one organism. Agrobacterium has even been shown to be able to transform mammalian cells.

The novel microbes and microbial toxins arising via HGT of artificial DNA will not be “old friends” and will certainly tax our immune system and promote inflammation. The potential for endemic mental health problems is inescapable.


The Institute of Science in Society is calling for a global ban to be imposed on further environmental releases of GMOs, and for all those responsible for releasing them to be brought to book.

  • Scientists Discover New Route for Gm-gene 'Escape', Institute of Science in Society Report 2.03.11
  • Linda Geddes, Happiness is catching, New Scientist, 15.01.11

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