Every week there is a report in the newspapers that a cure for dementia is just around the corner. As a gerontologist for more than 38 years, I have been waiting behind far too many corners. I have realised that there will never be one solution to dementia.
The way that science works is that we learn a lot about a multitude of specific mechanisms. Eventually all these different streams of knowledge come together to change our view of that disease – what Thomas Kuhn called “scientific revolutions”. This happens infrequently, and with dementia it still has not happened yet.
We still do not have a good idea of how the disease emerges and progresses. There are many conflicting studies and as yet we only have a general idea of what happens in the brain. Without this knowledge we continue guessing. One complication with the brain is that there are many causes that can result in a similar looking problem. And with the brain – being the most complex organ known in the universe – there are an impressive number of things that can go wrong.
The adult human brain has some 86 billion neurons. Each neuron has between 1,000 to 10,000 connections (synapses), making a total of 125 trillion synapses in the cerebral cortex alone. This is a thousand times the number of stars in our galaxy.
Now with each synapse there might be 1,000 micro switches. That makes over 125,000 trillion switches. A trillion has four groups of 000s (1,000,000,000,000). Numerous diseases can influence something so complex. So although the common view that there are some protein problems with the brain (plaques and tangles) that are more common among people with dementia, there are people who live well regardless of the plaques and tangles in their brain.
Studies have shown that there are multiple traumas that can infect and damage the brain; and that this damage can either be fixed by the brain itself, or it can grow to infect other parts of the brain.
The initial trauma that starts most dementias is unknown. Although most of the research focuses on genetic mechanisms, there is growing evidence that other, more relevant mechanisms: viral (HIV/AIDS, herpes simplex virus type I, varicella zoster virus, cytomegalovirus, Epstein-Barr virus), bacteria (syphilis and lyme-disease/borrelia), parasites (toxoplasmosis, cryptococcosis and neurocysticercosis), behaviour (alcohol, cigarette smoking, recreational drugs, concussion), environmental elements (possibly aluminium), infections (possibly prions such as in Cretchfeldt-Jakobs disease), vascular causes (stroke, multiple-infarct dementia, hydrocephalus, injury and brain tumours) and emotional trauma (abuse and depression). There are numerous studies, in their thousands, that correlate all of these factors with dementia.
All these variables – genetic, viral, bacteria, behaviour, environmental, vascular and emotional – act as a trauma, a shock, to the brain, affecting it independently or in combination. There might be other traumas that are as yet unidentified. But once there is a trauma to the brain, then the brain reacts in a very specific way. Researchers a century ago reported that there was a shadow, a halo caused by the trauma. Clinically, this is referred to as a penumbra.
The only cure will come from making our lives safer and healthier. Such a cure remains too far away
There seem to be two possible ways to stop the spread of this shadow if it is caught early enough. One method is for the brain itself to grow new cells to compensate. This is known as cerebral plasticity, or neurogenesis – potential for neurons and glial cells to grow. The second method is for the brain to get enough oxygen and energy to survive and grow. This is known as perfusion.
Taking a simple pill, however effective, might be beneficial but it can never cure dementia because there are many causes of it and they have many routes that lead to the expression of the disease. By accepting the evidence of multiple ways that can start the disease, which no pill can cure, then we start seeing the problem as a public health issue.
We can reduce dementia initially by reducing and lowering the exposure to traumas through education and laws. Reduction of concussions (in sport, military, recreational activities) should be made a priority. Programmes that reduce smoking, heavy drinking, as well as environmental toxicity, will promote a healthier brain.
Increasing physical activity provides an incentive for families to promote daily activities among adults of all ages. City walkability programmes and social engagement programmes all promote walking, swimming, light exercise, gardening, dancing, music and other brain exercise all have protective factors as well as show promise of reversing early stages of the disease.
Adjusting the focus onto the public health arena educates us to stop looking for a pill to cure dementia. The only cure will come from making our lives safer and healthier. Such a cure sadly remains too far away from any corner.
Mario Garrett was born in Malta and is currently a professor of gerontology at San Diego State University in California, US.