CARDIOVASCULAR JOURNAL OF AFRICA • Vol 21, No 4, July/August 2010
210
AFRICA
stressors.
8,10
The same authors illustrated that in African men, an
exaggerated peripheral resistance response could be seen.
4,10,11
The perception of daily events as stressful might result in a
negative experience of physical health, psychological distress
and perceived poor health. These experiences may manifest as
subjective stress, resulting in an exaggerated vascular response
and subsequent increases in BP.
33
Regarding the cardiovascular profile, our data revealed a
practical significance for lower arterial compliance predicting
HT (odds ratio 9.75), but it was also positively associated with
the development of target end-organ damage.
34,35
The cardiovas-
cular profile in urban African men was additionally associated
with depression. As 28% of them were severely depressed, a
vicious circle seems apparent and CVD risk could be increased if
psychological distress or depression persists.
36
It has been shown
that hypothalamic–pituitary–adrenocortical (HPA) axis hyperac-
tivity has been associated with both hypertension and depression.
Whether HPA hyperactivity is a possible mechanism for the
above associations in this population remains an unsubstantiated
speculation that will require further investigation.
37-39
A logistic regression analysis was also performed to show
the effect size of depression, perception of health and cardiovas-
cular variables as predictors for HT. Other studies have shown
that in men, depression has been significantly associated with
a variety of cardiovascular disorders, particularly the elevation
of MAP.
17,40,41
In this study, though, a weak association between
depression and MAP was found only in hypertensive women.
Depressed women were 1.15 times more likely to develop hyper-
tension than men, indicating that depression had a greater effect
on HT in women than the other measured predictors. Therefore,
individuals who were depressed had a greater chance of develop-
ing hypertension. As was found in African-Americans, depres-
sion was predictive of later incidence of hypertension.
42
The possible reasons for this discrepancy in findings may lie
in the difference in the populations under study. Different back-
grounds, socio-economic status, living conditions and levels of
stress and depression may be additional confounders for compar-
ing studies in different settings. Moreover, the use of different
psychological models in diagnosing depression may result in an
incongruity in the sensitivity of the instruments.
Lastly, the urban African men revealed a 24-hour mean BP
of 138/89 mmHg, which was higher than the ESH recommenda-
tions (
>
125–130/
>
80 mmHg), suggesting a possible need for
new cut-off values (24-hour AMBP) for Africans. On the other
hand, it could also indicate the seriousness of uncontrolled BP in
urban black African men experiencing increased psychological
distress, because only 16% of the HT men used antihypertensive
medication and 79% conformed to the ESH criteria of hyperten-
sive status. We therefore recommend that pre-hypertensive levels
should be monitored and addressed with early non-pharmacolog-
ical lifestyle modifications.
Possible limitations of the study include the small size of the
study sample when subjects were divided in HT and NT groups.
Future research should incorporate the measure of psychological
well being in addition to the measure of psychopathology, as it
will provide a broader continuum for the classification of the
mental health of those individuals falling within the threshold
category. The lack of symptoms of depression in a certain part
of the current sample should therefore not be interpreted as the
presence of mental health.
Conclusion
This study showed that depression was significantly associated
with certain measured cardiovascular variables and that depres-
sion was the most prominent contributor to HT. Major depression
was associated with the development of pathological conditions
such as the development of LVH, lower vascular compliance and
elevated MAP, possibly through hyperactivity of the sympathetic
nervous system. Perception of poorer health, in particular soma-
tisation, could contribute to autonomic dysfunction in both men
and women. The limited number of similar studies in an African
population serves as motivation for more research in this area.
The authors acknowledge the contributions of the following SABPA team
members: the anthropometric measurements done by biokineticists, super-
vised by Prof JH de Ridder, cardiovascular measurements supervised by
cardiovascular physiologists, and the psychological data supervised by
psychologists. This study was financially supported by the North-West
University: AUTHER (African Unit for Transdisciplinary Health Research),
and the National Research Foundation (NRF), Metabolic Syndrome Institute
(France).
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