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<h5 class="section-title" id="d347787e215">Background</h5>
<p id="P1">Chronic psychological stress is a risk factor for cardiovascular disease
and mortality.
Circulating hematopoietic progenitor cells (CPCs) maintain vascular homeostasis, correlate
with preclinical atherosclerosis, and prospectively predict cardiovascular events.
We hypothesize that 1) chronic caregiving stress is related to reduced CPC number,
and 2) this may be explained in part by negative interactions within the family.
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<h5 class="section-title" id="d347787e220">Methods</h5>
<p id="P2">We investigated levels of stress and CPCs in 68 healthy mothers - 31 of
these had
children with an autism spectrum disorder (M-ASD) and 37 had neurotypical children
(M-NT). Participants provided fasting blood samples, and CD45
<sup>+</sup>CD34
<sup>+</sup>KDR
<sup>+</sup> and CD45
<sup>+</sup>CD133
<sup>+</sup>KDR
<sup>+</sup> CPCs were assayed by flow cytometry. We averaged the blom-transformed
scores of both
CPCs to create one index. Participants completed the perceived stress scale (PSS),
the inventory for depressive symptoms (IDS), and reported on daily interactions with
their children and partners, averaged over 7 nights.
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<h5 class="section-title" id="d347787e244">Results</h5>
<p id="P3">M-ASD exhibited lower CPCs than M-NT (Cohen's
<i>d</i>=.83;
<i>p</i>≤.01), controlling for age, BMI, and physical activity. Across the whole sample,
positive
interactions were related to higher CPCs, and negative interactions to lower CPCs
(
<i>all p's</i><.05). The adverse effects of group on CPCs were significantly mediated
through negative
interactions with the child (indirect
<i>ß</i>=−.24,
<i>p</i>≤.01). In the full model, greater age (
<i>ß</i>=−.19,
<i>p</i>=.04), BMI (
<i>ß</i>=−.18,
<i>p</i>=.04), and negative interactions with the child (
<i>ß</i>=−.33,
<i>p</i><.01) were independently associated with lower CPCs. M-ASD had a less healthy
lipid
profile (total cholesterol/HDL), which in turn, was associated with lower CPCs.
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<h5 class="section-title" id="d347787e283">Conclusions</h5>
<p id="P4">Chronic stress adversely impacts CPC number, an early-stage biomarker that
predicts
subclinical atherosclerosis and future CVD events, independent of traditional cardiovascular
risk factors and inflammatory factors. Among maternal caregivers, child-related interpersonal
stress appears to be a key psychological predictor of stress-related CVD risk.
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