What did this research uncover?

In this study, platelets and peripheral blood mononuclear cells from 308 individuals aged 0-86 years was analysed with high-resolution respirometry. No major decline in mitochondrial respiration with age was seen for neither blood cell type. Nor did mitochondrial content change significantly with age. These findings were contrary to the hypothesis that mitochondrial function declines with age. 

Why are these results important?

Mitochondrial respiratory function have long been considered integral to the process of biological aging. Its exact role in ageing, however, is complex and not fully understood. The decline of mitochondrial respiration has previously been investigated mainly in muscle fibres; previous studies in human blood cells have been small and contradicting.

The publication of negative results is important in the scientific community to counteract publication bias and these results call into question the theory of universal mitochondrial decline with age. The results may also have implications for future research on the aging immune and coagulation systems.

Are there limitations to the study?

Yes. The study comprises a retrospective cohort consisting both of healthy individuals and of patients with various disorders and diseases. The reason was to increase sample size and power. Health status was adjusted for in the analyses but the risk of confounding can never be completely eliminated. In addition, one should always be cautious about negative results. The absence of significant results is not a conclusive proof that no association exists.