Time to start dying.
I have just re-read the opening paragraph to my 1979 Ph.D thesis on the Biochemistry of Ageing (Rat Mitochondria). It laid out the goal of the field of study called gerontology. In a nutshell, the goal was: ‘the extension of years of active life before entering the senescent phase’. It also said explicitly that increased life span due to prolongation of the senescent phase was a bad idea, something I feel with which few would disagree.
Unfortunately I think in the last fifty years we have achieved mostly the latter and in the worst way. There has been an increase in UK average maximum life span ( about 3 years more for men and women) in that time but I am increasingly thinking that the senescent phase is starting earlier.
In the UK the cost to the taxpayer of supporting the long term sick is large, increasing and unsustainable. I think a great many of this group have entered a senescent phase, or at least a version of it. This assertion needs a lot of unpacking to sound credible.
Firstly we expect old people to look old. We readily recognise superficial phenotypes denoting ‘old’; low energy, wrinkles, faltering gait, muscle loss, incontinence and bone fragility to name a few. Some of these such are products of deteriorating connective tissue which is a time-dependent passive chemical process rather than a reflection of physiological or biochemical ageing. Physiological changes, say to do with muscles or the brain on the other hand are under active processes. Processes we now know are ultimately mediated by mitochondria via internal and external signals
Now, the broad signals for a cell or a body to enter a senescent phase are well known. They are DNA damage ( eg from radiation, pollution,toxins) , epigenetic ( eg onco-viral), telomere erosion ( the ability for a cell to divide) and mitochondrial dysfunction. All except telomere erosion can be influenced by environment, diet and lifestyle.
To follow the argument in this post you need to imagine a senescent individual who does not look old. So his/her limbs and body will remain plump, skin smooth-ish, and heads hairy. They will however also be largely inactive ( low energy) and suffering from chronic inflammatory diseases like arthritis and IBS and dementia. Low immune surveillance will also lead to an increase in early onset cancers especially where inflammation is high, eg the gut. Sarcopena ( muscle loss ) will also be evident, though largely hidden by intramuscular fat. Finally, mental health issues such as depression and anxiety come to dominate cognitive processes.. In all respects characteristics of folk in teh senescent phase.
How could this happen? How did the ‘not-old’ enter a senescent phase? ‘Signals’ are received and acted upon by an organism on very many levels. For example mitochondria ‘note’ energetic demands, the amount and character of ‘food’ being delivered, the level of damage in the cell, the activity of endogenous and exogenous viruses, exposure to NIR light at dawn and dusk. The list goes on, and mitochondria proliferate or die or kill the whole cell depending on what they find.
At a more complex level the mind responds with behavior changes according to the perception of the environment, broadly divided into good times or bad times. Bad times triggers reduction in mating and vice versa.
As you can see in the profile of the Ist World human there are plenty of candidates to signal ‘it’s all over chums go into senescence’ . And with very bad luck modern medicine will prolong this phase even longer. Happy days.
