'Sick and Tired'? Not Merely a Phrase

Highlights

• Self-reported tiredness or fatigue is a partly heritable, complex phenomenon.
• Study found that being genetically predisposed to a range of mental and physical health complaints also predisposes individuals to report that they are more tired or lacking in energy.
• The conditions can range from physical conditions diabetes, cancer, arthritis to certain habits like smoking, carrying the risk of being overweight and also mental health status.

Fatigue is a common complaint. Genes might contribute in a small but significant way to whether people report being tired and low in energy. The findings are according to UK researchers led by Vincent Deary of Northumbria University, Newcastle, and Saskia Hagenaars of the University of Edinburgh.

Fatigue or feeling tired is associated with physical and mental health status.It is commonly reported in a number of health conditions like diabetes, cancer, cirrhosis, Parkinson's disease and rheumatoid arthritis.

The researchers found that 8% of people's differences in self-reported tiredness/low energy can be attributed to genetics which implies that the vast majority of people's differences in self-reported tiredness are environmental in origin.

Genetic predisposistion to a range of mental and physical health conditions, and with habits like smoke, or being obese, and also longevity accounted for the small genetic contributions to self-reported tiredness.

Genetic Predisposistion to Fatigue

In a large-scale study, researchers analyzed genetic information of 111,749 participants who all indicated whether they felt tired or low in energy in the two weeks before their data were collected in the UK Biobank study.

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The researchers conducted various statistical analyses, including genome-wide associations, heritability estimates, and testing genetic associations between tiredness and more than 25 health-related variables after considering factors such as age and gender.

The findings suggest that not just the illness but the genetic proneness to some illnesses, that had an association with self-reports of tiredness.

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When researchers examined people who were genetically prone to diabetes but did not have the condition, they found that a small genetic link with tiredness remained intact.

The researchers concluded that a genetic overlap was found to exist between tiredness and a general tendency to poor health.

"Being genetically predisposed to a range of mental and physical health complaints also predisposes people to report that they are more tired or lacking in energy," added Hagenaars.

Genetic association were found between tiredness and conditions like:

• metabolic syndrome like high cholesterol levels, and a high waist to hip ratio or obesity
• schizophrenia
• longevity
• weak grip strength
• smoking
• depression

A tendency for more mental and emotional distress also leads to reports of being tired.

The results confirm that self-reported tiredness is a partly heritable, complex phenomenon that has genetic associations with various health, physiological, cognitive, personality, and affective processes.

The genetic data available accounted for only 8.4% of people's differences in tiredness and most of people's differences in tiredness are probably environmental.

"Although tiredness is largely causally heterogeneous, there may be a small but significant direct genetic contribution to tiredness proneness," Deary said, summarizing the findings of this part of the study.

The research team foresees that more tests to find such links will be done in future as more genome-wide genotyping data becomes available.

The report is published in Springer Nature's journal Molecular Psychiatry.

Reference

1. Vincent Deary et al. Genetic contributions to self-reported tiredness. Molecular Psychiatry; (2017) doi: 10.1038/mp.2017.5

Source-Medindia