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

This study contributes to investigating the effect of caffeine on telomere length in people with different mental disorders. 

On the one hand, it is known that these individuals experience telomere shortening, which is considered a sign of ageing and a cause of diseases including cancer. On the other hand, protective mechanisms against this ageing include, in addition to physical exercise and proper diet, the intake of antioxidants such as those found in tea or coffee. 

The authors, in accordance with recent publications, point out that high doses of coffee contribute to telomere shortening, while low amounts increase their size to the point where they resemble those found in younger people. 

Although there are many factors that can contribute to telomere length, the results obtained in this study are very interesting and point to the antioxidant and protective effects of many of the components of coffee.

This Norwegian study examined a measure of ageing, telomere length, in a relatively small sample of patients with schizophrenia and bipolar disorder, and linked it to coffee consumption. The authors observed a positive relationship between moderate coffee consumption and lower biological ageing. The study is preliminary and requires replication.  

Among its weaknesses, it should be noted that the measurement of coffee consumption was very simple (cups) and based on self-reporting by the subjects (relatively unreliable). Furthermore, with this methodology, we do not know which component of coffee has these properties. It could be caffeine or other components with antioxidant action. Other sources of caffeine, times of consumption, and coffee format (short, long, with milk, etc.) were not controlled for either. The study is cross-sectional, and it would be desirable to confirm the findings in a longitudinal and better-controlled study. There is no healthy control group to see if the findings are limited to the population with psychiatric disorders.  

Coffee consumption in people with mental illness can have beneficial effects, but also harmful ones, especially if it affects sleep duration and quality, a crucial aspect of maintaining stability when suffering from an illness such as schizophrenia or bipolar disorder. With its limitations, the study suggests that moderate coffee consumption, and I would add in the morning, may have beneficial effects on physical health and expected longevity (measured biologically) in people with mental disorders, if these results are confirmed.

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.

The study conducted by Mlakar et al. analyses, in a cohort of patients with schizophrenia and severe mood disorders, the relationship between coffee consumption and telomere length as a marker of cellular aging. Previous studies have linked depression, post-traumatic stress, and psychiatric disorders with increased biological age, although there are discrepancies depending on the methods used. The authors found an inverted J-shaped relationship: moderate coffee consumption (up to four cups) is associated with longer telomeres, equivalent to a lower biological age. In other words, they found an optimal effect with the consumption of four cups, while this benefit disappears with five or more cups per day.

Although the study is an interesting start in exploring the role of coffee in the health of psychiatric patients, the work has significant limitations that mean it should be interpreted with caution. First, as it is a cross-sectional and observational design, causality cannot be established. The association observed could be due to other uncontrolled factors in the study, such as the patient's overall lifestyle or metabolic health. Nor is any distinction made regarding the type of coffee. The decline in benefit after five cups could be explained by the consumption of instant coffee, which, according to previous studies in the general population, has a negative effect on telomeres, unlike filtered coffee. Furthermore, although the authors suggest that bioactive and antioxidant compounds are responsible for the benefit—rather than caffeine itself—the study did not measure markers of oxidation or inflammation to confirm this, nor did it investigate the mechanisms that may be behind this effect.

In conclusion, this is an interesting study that opens the door to investigating coffee as part of the lifestyle in psychiatry, but it cannot be concluded that it is justified to 'prescribe' coffee for psychiatric illnesses. The most prudent approach is to integrate these findings into a broader context: maintaining an active lifestyle and a healthy dietary pattern, such as the Mediterranean diet (which includes moderate coffee consumption, preferably not instant), remains the most robust strategy for reducing biological age and maintaining a healthier life.