Surviving traumatic events could help you live longer

"Men who survived the Holocaust outlive Jewish men of the same age," reports the Mail Online.

The story is based on research looking at the survival of more than 55,000 Polish Jews who migrated to Israel either before or after the Second World War. During the war, Poland's Jews were persecuted by occupying German and Soviet forces – part of what is known as the Holocaust, or Shoah.

Researchers wanted to find out how lifespan was affected by people's experience of the Holocaust. Those who emigrated from Poland after the war were deemed likely to have had first-hand experience, either living in a ghetto or in hiding, or surviving concentration camps.

Being exposed to extremely distressing and traumatic events has been thought to damage people's long-term health and lead to a shorter lifespan. But the study found that some age groups of men in the Holocaust survivor group actually lived longer on average than those of the same age who immigrated to Israel before the war.

The researchers suggest two possible explanations for their findings. First, the individuals who survived the war may have been less vulnerable than those who died, predisposing them to surviving longer. The second explanation could be that people who experience severe trauma have some form of "post-traumatic growth" that makes them live longer, such as experiencing more appreciation of life.

It is not possible to say which, if either, of these explanations is correct. It seems plausible that the first explanation could explain at least some of the difference. The reason why the link was found only in men and not women is not clear and may be investigated further.

Where did the story come from?

The study was carried out by researchers from the University of Haifa in Israel and other research centres in Israel and the Netherlands. The authors were supported by funding from the Netherlands Organization for Scientific Research and a Phyllis Greenberg Heideman and Richard D Heideman fellowship.

It was published in the peer-reviewed open access journal, PLOS One.

The Mail Online covered this research as though it had shown that post-traumatic growth was the reason for increased longevity. However, the study cannot explain why the difference in longevity was seen and the authors only suggest that post-traumatic growth could be one reason.

The Mail also implies that the male survivors had been in concentration camps. While this may be true for many in the group, the study did not assess what each individual's experiences of the war were –  for example, whether they were in concentration camps, in hiding or in ghettos.

The Mail headline also suggests that the findings could be applied to all people who suffer adversity, but this should not be assumed.

What kind of research was this?

This was a retrospective cohort study that investigated whether surviving the Holocaust has had an impact on life expectancy. The researchers say that survivors of the Holocaust or other genocides might have reduced life expectancy because of the extreme psychosocial trauma, malnutrition, poor sanitary conditions and lack of healthcare they experienced.

The researchers report that some studies have suggested that the ageing of our cells may be speeded up by exposure to early life adversity. However, the effects on life expectancy are not well understood, as findings have been inconclusive.

This type of study is the only way of studying the long-term effects of this type of atrocity.

What did the research involve?

The researchers studied all immigrants to Israel from Poland who were born between 1919 and 1935. These individuals would have been aged between four and 20 years old when the Second World War started (when Poland was invaded by Nazi Germany and the Soviet Union). They compared the lifespans of those who immigrated before the Second World War started in 1939 with those who immigrated after the Holocaust between 1945 and 1950.

The researchers obtained their data from the National Insurance Institute of Israel and only included people who were alive on January 1 1950. Any Jewish person who lived in Poland between 1939 and 1945 was defined as a Holocaust survivor, but their specific experiences were not assessed. Those migrating during the war (1940-44) were not included to ensure that those involved in the study had survived the whole period of the Holocaust.

There were 55,220 participants, which included 41,454 survivors of the Holocaust and 13,766 comparators. The researchers identified deaths of people in the study population between 1950 and 2011. Only deaths in people aged over 16 were recorded. In 2011, the average age of the Holocaust survivor group was 85.3 years and of the comparison group was 85.6 years.

The researchers compared survival over time in the Holocaust survivor group and comparator group, taking gender into account. After their overall analyses, they explored whether gender and age at the start of the Second World War influenced differences in survival.

What were the basic results?

The researchers found that Holocaust survivors lived about 6.5 months longer on average than those who did not experience the Holocaust (hazard ratio of death [HR] 0.935, 95% confidence interval [CI] 0.910 to 0.960).

When they looked at men and women separately, they found that only men who experienced the Holocaust lived significantly longer than men who had not been exposed. Generally, women tended to live longer than men, but there was no significant difference between women who had survived the Holocaust in Poland and those who emigrated beforehand.

The difference was greatest in men aged 10-15 and those aged 16-20 at the start of the Holocaust. The 10- to 15-year-olds lived about 10 months longer on average (HR of death 0.900, 95% CI 0.842 to 0.962). The 16- to 20-year-olds lived about 18 months longer on average (HR 0.820, CI 95% CI 0.782 to 0.859). No effects were seen in women in any age group, or in men aged 4-9 years old at the start of the Second World War. 

How did the researchers interpret the results?

The researchers concluded that, "Against all odds, genocidal survivors were likely to live longer". They suggest that there could be two explanations for this:

• individuals surviving severe trauma may have characteristics that predispose them to live longer
• so-called "post-traumatic growth" was responsible, where individuals who have lived through severe trauma may, for example, experience greater meaning in their lives, more life satisfaction and more social and emotional support because of their past experiences

Conclusion

This interesting study suggests that Polish men who survived the Holocaust and immigrated to Israel live longer than Polish men who immigrated before this atrocity. 

The study has many strengths, including its large size and ability to include all migrants from specified periods. The fact that these migrants were born in the same time period in the same country (Poland) and migrated to the same country (Israel) should also reduce differences between the two groups.

The authors note that they did not assess individuals' actual experiences in the Holocaust, which may have varied. For example, it is not known how many of the Holocaust survivors had experienced concentration camps or how many were in hiding.

Also, for the comparison group who immigrated to Israel before the war and were therefore not considered to have experienced the Holocaust, it is not known to what extent they were indirectly exposed through the experiences of family or friends who stayed in Europe.

The authors also acknowledge that there may have been other differences between those migrating before and after the Second World War that could account for the differences seen. They did not have data on people who emigrated from Israel who may still have been counted as being alive even though they may have died abroad.

It is also not known whether similar results would have been obtained if they had looked at those who emigrated from Poland to countries other than Israel or those who stayed in Poland. Similar studies in other countries would be needed to confirm these results. It is also unclear why the link was only found in men and not in women.

It's not possible to say if these findings would apply to survivors of similar genocidal atrocities, such as more recent genocides in Cambodia or Rwanda. It's also not possible to determine whether the effect would be seen in other people who have experienced other forms of "life adversity", as the Mail headline suggests. The researchers also did not assess quality of life in the participants, which may have been poorer in individuals who experienced the Holocaust.

Overall, it is not possible to say for certain why life expectancy is longer among male Holocaust survivors. One possible explanation suggested by the authors is that only the healthiest and most resilient individuals would be able to survive the extreme mental and physical strain of the Holocaust. These individuals may have been more likely to live longer than average anyway.

A better diet, more exercise and good healthcare can all contribute to a longer, healthier lifespan. Discover the ways that you can adopt a healthier lifestyle.