Allostatic load score and lifestyle factors in the SWAN cohort: A longitudinal analysis

Objectives

Allostatic load (AL) has been used to assess chronic stress. Previous studies have assessed associations between lifestyle factors and the AL. However, those studies have yet to evaluate associations longitudinally. Thus, the effect of lifestyle factors on the AL changes over time remains to be determined.

Study design

A longitudinal analysis was designed.

Methods

Our study included 1976 women identified from the Study of Women's Health Across the Nation (SWAN) who had completed at least seven waves of measurements since baseline. The Poisson mixed effects model was used to model AL and to assess how lifestyle factors affected AL over time.

Results

At baseline, the mean AL score was 2.44 (range 0–11). On average, the AL score increased by 3 % (ORs = 1.03, 95 % CI [1.01, 1.05]) per wave over time. For lifestyle factors, women who smoked cigarettes over time had higher AL than those who never smoked. On the other hand, women who ever drank alcohol at baseline, had leisure physical activity over time, and had at least average sleep quality at baseline, and had lower AL than their counterparts. We also identified a statistically significant interaction between alcohol drinking and time (P < 0.01). Furthermore, we generated a healthy score using the four lifestyle factors above to assess the potential accumulative effect of lifestyle factors on AL. We found that the AL increased by 16 % for each additional unhealthy lifestyle factor (ORs = 1.16, 95%CI: 1.12, 1.2).

Conclusions

This study demonstrates that lifestyle factors can influence the increase of AL over time.