Neuropsychiatric Symptoms of Epilepsy

236
A. Guekht
Introduction
Association between epilepsy and dementia has been described centuries ago [ 1 ].
Thomas Willis wrote that dementia could result from the “cruel diseases of the
head,” such as epilepsy [ 2 ]; the French Encyclopedia [ 3 ] also considered “incurable
diseases such as epilepsy” one of the causes of dementia.
In fact, neuropsychiatric problems are observed in 30–50 % of patients with
chronic epilepsy. Cognitive impairments, especially in memory, concentration, and
word finding are well known. Cognitive deficit in patients with chronic epilepsy is
multifactorial and includes the impact of the underlying etiology, the effects of
recurrent seizures, adverse effects of antiepileptic drugs, and psychosocial issues
[ 4 – 9 ]. However, there is an increasing evidence that patients with newly diagnosed
epilepsy are cognitively compromised even before the start of antiepileptic drug
medication. The cognitive domains most affected are psychomotor speed, higher
executive functioning, and memory [ 10 – 12 ].
On the other hand, seizures are frequently observed in patients with dementia.
The incidence of seizures among patients with dementia varies with the etiology of
the dementing illness [ 13 – 17 ]. Pohlmann-Eden reported that the spectrum of diseases
with dementia and associated seizures ranges from more frequent conditions
(Alzheimer’s disease) and vascular dementia (VaD), where seizures occur in a small
proportion of patients, to rare conditions (Creutzfeldt-Jakob disease) in which seizures
are a common reflection of the underlying epileptogenic neurobiological process
[ 18 ]. The incidence of epilepsy in persons with Down syndrome (DS) is 1.4–17
% and varies with age [ 19 – 23 ].
According to McVicker et al., seizures are quite prevalent at certain phases of
DS, and could be seen in about half of patients over age 50 [ 24 ].
There are a number of relatively rare conditions that are associated with earlyonset
dementia, myoclonus, and epilepsy: sialidosis, GM2 gangliosidosis, Lafora
disease, ceroidlipofuscinosis, and mitochondrial encephalomyopathies [ 25 – 27 ].
Dementia, stroke, and epilepsy are three most common neurological disorders in
the elderly; incidence rates of over 100 per 100,000 for epilepsy in people over 60
years of age have been reported [ 28 – 33 ]. Epilepsy, cerebral atherosclerosis, and
age-related cognitive disorders, including Alzheimer’s disease, share many clinical
manifestations, risk factors, and structural and pathological brain abnormalities.
Plaque deposits in gray matter were first described by Blocq and Marinesco as the
result of the examination of nine deceased epileptic patients in 1892 [ 34 ]. They did
not, however, relate the plaques to dementia; that was accomplished in 1906 by
Alois Alzheimer [ 34 – 37 ].
Alzheimer’s Disease and Epilepsy
Patients with AD have an increased risk of developing seizures and epilepsy. AD
and other neurodegenerative conditions represent the presumed etiology of 10 % of
new-onset epilepsy in patients older than 65 years [ 38 ]. There are some prospective