How to build a barrier to dementia

And keep up regular maintenance

Standing between you and many brain disorders is a wall, or barrier. It’s a very thin but powerful membrane that requires regular maintenance. Neglect it, and your brain may be exposed to attack from hostile agents as they manage to gain access.

OK, that’s a bit dramatic but it is essentially true. A damaged blood brain barrier can leave you vulnerable to neurodegenerative diseases, including Alzheimer’s disease.

The blood brain barrier, in brief

The theory of a barrier between blood and brain was first proposed in 1906, when experimental intravenous injection of a dye was seen to stain all the tissues of the body, but not the brain. The existence of the barrier was confirmed nearly 50 years later when it became visible using microscopic technology.

The blood brain barrier (BBB) is a tightly packed layer of cells lining the blood vessels of the brain and spinal cord, held together by tight junctions. Its role is to block harmful substances, including heavy metals, bacteria, viruses and environmental toxins, from entering the central nervous system. At the same time, it must allow essential substances to make the crossing unimpeded.

These substances include nutrients, oxygen, amino acids and glucose. The healthy BBB is highly selective about what may, and what may not, pass from the general circulation into the brain.

The BBB has a lot of territory to cover: there are approximately 400 miles of blood vessels in the human brain, supplying oxygen and nutrients and removing waste products before dispatching them to the general circulation.

Increased permeability of the BBB is a well-known phenomenon in neuroscience. If circulating debris, microbial pathogens, and inflammatory metabolites encounter gaps in the wall, they are given free passage to the brain where they can trigger the start of disease.

“A dysfunction of the blood brain barrier leading to a ‘leaky brain’ can be linked to various neurological diseases, including autistic spectrum disorder (ASD), dementia, Alzheimer’s disease, depression, and schizophrenia.”

Lifestyle factors play a major role in the disruption of the BBB and the start of neurodegeneration. This is especially the case in dementia. Nothing disrupts the BBB quite like inflammation.

Alzheimer’s can take root at the BBB, where inflammation initiates the process of dysfunction. This inflammation spreads from the barrier to other regions of the brain, enabling the disease to progress.

MRI scans of people with mild cognitive impairment reveal dysfunction of the BBB in the region of the hippocampus, the brain’s main memory centre. Postmortem evidence demonstrates brain capillary leakages and degeneration of brain cells, alongside infiltration of leukocytes (inflammatory substances), and certain inflammatory proteins.

Where diet comes in