Reacción a "Moderate coffee consumption may slow biological ageing in people with severe mental disorders, according to a study"

Mlakar and colleagues show that, in individuals suffering from mental illness, caffeine consumption can cause telomere lengthening, which is interpreted as a “rejuvenation” of about five years.  

The study focused on individuals with schizophrenia or affective disorders recruited in Norway, as these individuals have shorter telomeres than the general population. 

This study analyses various factors in a population of individuals affected by mental illness who belong to a cohort that has been followed for several years between 2007 and 2018. A cohort is a group of individuals selected for one or more reasons, usually the presence or absence of a disease, who are studied periodically to find out how that disease evolves. 

In this cohort, the size of telomeres isolated from white blood cells taken from a blood sample was analysed and compared between groups created based on daily coffee consumption. This comparison shows that individuals with longer telomeres are also those who consume 4-5 cups of caffeinated coffee per day. It also shows that higher consumption is not associated with longer telomeres. For this analysis, the authors took into account not only these two factors, coffee consumption and telomere length, but also considered factors that may directly or indirectly affect either one. Similarly, they did not take into account factors that may also influence these characteristics: physical activity, type of diet, consumption of medication for the disorders under study, or other chronic problems that may be present. This can affect both the tendency to consume more or less coffee and the length of the telomeres themselves. 

The results of this study suggest that caffeine, in doses at the high end of what is considered healthy, around 400 mg/day, could have a positive effect by halting the telomere shortening normally seen in these mental disorders. Existing evidence indicates that these disorders are associated with telomere shortening, which is also greater in individuals with more severe manifestations. 

This study did not include other known factors that could play a role in telomere length, such as the severity of the patients' disease, their diet, whether they get enough physical activity, or their exposure to environmental toxins (pollution, pesticides, etc.). This does not invalidate the study, but it does serve to contextualise the main finding. 

The reasons why people with these disorders have shorter telomeres are not clearly understood. Furthermore, it should be noted that these studies are conducted on blood cells and are not usually conducted on cells of the nervous system, which is where the pathophysiological basis of these disorders lies.  

Epidemiological studies have shown that certain environmental factors are important in accelerating/delaying the telomere shortening associated with ageing: obesity, depression, exposure to pesticides or pollution, or chronic stress, but the mechanisms involved are not known. 

As for mental illness, it has long been known that shorter life expectancy coincides with telomere shortening. Again, the reason for this association is unknown. 

Various studies show that in the general population, consuming up to 4-5 cups of caffeinated coffee per day has no negative effects and, depending on the individual, can even have positive effects. However, this does not imply that these effects are due to telomere lengthening or a decrease in their rate of shortening. It should be remembered that the study focuses on a population that, from the outset, has shortened telomeres, and the study observes that coffee consumption is associated with an increase in their size. Transferring this to different situations cannot be done without running the risk of drawing conclusions that are not based on the data. 

There are studies that suggest that healthy diets are associated with longer telomeres. Specifically, those who follow the Mediterranean diet have longer telomeres. Something similar is observed in diets based on the consumption of plant foods, where healthy foods (nuts, rich in fibre) are differentiated from less healthy foods, with telomere length being greater in the former. However, the situation is not so simple to understand. For example, in a study with a calorie-restricted, Mediterranean-type diet, a slowing of telomere shortening was observed, but only in women and not in men.