Neuropsychiatric Symptoms of Epilepsy

15 Stress and Epilepsy
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adherence was reported as similar between groups in the Croatian study. That said,
larger population-based studies also support an association. A Danish national registry
study, examining the influence of losing a child on the subsequent risk of epilepsy
in either parent, demonstrated a significant 50 % increased risk overall in
bereaved versus non-bereaved parents, particularly in fathers within the first 3 years.
This could not be explained by sociodemographic factors, and is truly population
based, though the effects of potential lifestyle confounders such as alcohol and substance
abuse, and misdiagnoses could not be excluded [ 22 ]. A retrospective analysis
of medical information and duty assignments (combat, maintenance, or administrative)
from over 300,000 compulsorily drafted Israeli Defense Forces males followed
for 30 months gave conflicting results [ 23 ]: The risk of new onset seizures was
slightly (RR 1.29, 95 % CI 1.03–1.62), but significantly ( p = 0.03) higher in the
“high stress” combat than other units. However, in those with previous or current
epilepsy (some of whom if seizure free, and off treatment with normal EEGs were
assigned to combat), there was no identifiable effect on risk of recurrence.
There are a smaller number of prospective studies though hampered by a lack of
clear definitions and standardized assessment tools. Stressful verbal stimuli presented
to healthy controls have been shown to produce subtle EEG changes (narrowing
of the bandwidth and regional changes in frequency) of sufficient magnitude
that a blinded reviewer could correctly identify 92 % of stress stimuli on EEG
alone [ 24 ]. Similarly in people with a variety of epilepsies, stressful interviews
induced changes (exaggerated spiking, paroxysmal activity, or epileptiform complexes)
in the majority [ 25 ] and there are case series of stress inducing audio/video
recordings inducing seizures in patients with temporal lobe epilepsy in particular
[ 26 ]. There are few larger or longer term truly prospective studies (Table 15.2 ).
These broadly support an association, but have struggled to separate the effects of
stress per se from confounders such as sleep deprivation, alcohol, and missing
medication, or to separate cause from effect. However, as highlighted by one of the
most recent prospective studies, the relationship between, and difficulties distinguishing
stress from premonitory sensations and mood is particularly challenging
to disentangle [ 27 ]. Thus changes in the brain preceding a seizure might increase
patient perceptions of stress and anxiety rather than the converse. Nonetheless,
overall there is reasonable support from clinical studies that stress might lower
seizure thresholds, on which basis we now proceed to look more closely at putative
mechanisms.
Mechanisms and Consequences of Stress
The definition of stress depends on the context. In lay usage, stress is defined in the
Oxford English Dictionary as “A state of mental or emotional strain or tension
resulting from adverse or very demanding circumstances.” In the historical scientific
study of stress, as reviewed by [ 31 ], Claude Bernard (1865) noted that the
maintenance of life is critically dependent on keeping our internal milieu constant