Interpretation
Previous studies have shown cognitive decline months to years after a
pregnancy complicated by pre-eclampsia.17-19 To our
knowledge no studies have assessed cognitive function before delivery or
assessed cognitive function objectively at time of disease. Our findings
would imply that the cognitive decline observed postpartum in earlier
studies does not exist before onset of disease and is reported only in
pre-eclampsia with severe features after diagnosis. To support this
theory, subjective cognitive decline seems to increase by severity of
disease and in particular by number of fits in women with previous
eclampsia, arguing for a dose-response mechanism.17 It
would be important to follow up our findings with long term studies to
assess if these acute findings found in our population are reversible
and if they correlate with longer term impaired cognitive function
months to years after the pregnancy. In addition, cognitive function
needs to be studied in combination with cerebral imaging and more
in-depth cognitive function assessment on short- and long-term.
The CFQ was developed to assess cognitive function using daily life
activities and does not have a cut off for normal function. It is
recommended to perform the CFQ in generally comparable groups and to
compare scores on a group level. The CFQ is a retrospective instrument
subject to the limitations of human memory. It has been reported to
change after severe physical stress or trauma like a brain injury and
might be affected by a severe disease such as pre-eclampsia and in
addition, CFQ has been designed to be used in a high income
setting.20 Yet, the CFQ is the most commonly used
assessment for cognitive function after
pre-eclampsia.19, 21, 22 In our study, many of the
participants live in poverty and some of the items on the CFQ were not
applicable. Examples include questions such as ‘Do you find yourself
forgetting why you went from one part of/room in the house to the
other’. Many of the women in our study live in a single room where they
sleep and eat. ‘Do you find yourself forgetting what you came to the
shop to buy?’ was also problematic as many answered that they always
only buy white bread. Although this may have influenced the outcomes,
the groups were comparable.
The MoCA test was also developed in a high income setting and a score of
26 points is the cut off for normal cognitive
function.16 In our population, even though women with
normotensive pregnancies and non-complicated pre-eclampsia scored
higher, the mean scores in these groups were 25.8 and 26.1 points
respectively which correlates to borderline normal cognitive function.
In a cross sectional study examining 370 healthy 18 year old South
African males and females, the optimal cut off for sensitivity and
specificity to detect cognitive impairment through the MoCA test was 24
points.23 Thus, women with normotensive pregnancies
and non-complicated pre-eclampsia in our study scored above the
suggested cut off for cognitive impairment whereas women with severe
pre-eclampsia and in particular eclampsia scored below the limit of
normal cognitive function. Many of the women with pre-eclampsia with
severe features, including all those with eclampsia, were treated with
magnesium sulphate for neuroprotection during their hospital stay.
Magnesium sulphate has been shown to improve cognitive function in
pregnant women.24 However, magnesium sulphate was not
administered at the time of testing and scores were generally lower in
women that had undergone treatment with magnesium sulphate
(predominately women with eclampsia).