Geriatric epilepsy: research and clinical directions for the future

Seizures in Alzheimer's disease are highly recurrent and associated with a poor disease course

BACKGROUND

Seizures are an important comorbidity in Alzheimer's disease (AD). Conflicting results regarding clinical parameters associated with seizures in AD were previously reported. Data on seizure recurrence risk, a crucial parameter for treatment decisions, are lacking.

METHODS

National Alzheimer's Coordinating Center data were analyzed. Seizure prevalence in AD and an association with disease duration were investigated. Associations of seizures with age of AD onset and with cognitive and functional performance, and seizure recurrence risk were studied.

RESULTS

20,745 individuals were investigated. In AD dementia, seizure recurrence risk was 70.4% within 7.5 months. Seizure history was associated with an earlier age of onset of cognitive symptoms (seizures vs. no seizures: 64.7 vs. 70.4 years; p < 0.0001) and worse cognitive and functional performance (mean MMSE score: 16.6 vs. 19.6; mean CDR-sum of boxes score: 9.3 vs. 6.8; p < 0.0001; adjusted for disease duration and age). Seizure prevalence increased with duration of AD dementia (standardized OR = 1.55, 95% CI = 1.39-1.73, p < 0.0001), rising from 1.51% at 4.8 years to 5.43% at 11 years disease duration. Seizures were more frequent in AD dementia compared to normal controls (active seizures: 1.51% vs. 0.35%, p < 0.0001, OR = 4.34, 95% CI = 3.01-6.27; seizure history: 3.14% vs. 1.57%, p < 0.0001, OR = 2.03, 95% CI = 1.67-2.46).

CONCLUSION

Seizures in AD dementia feature an exceptionally high recurrence risk and are associated with a poor course of cognitive symptoms. AD patients are at an increased risk for seizures, particularly in later disease stages. Our findings emphasize a need for seizure history assessment in AD, inform individual therapeutic decisions and underline the necessity of systematic treatment studies of AD-associated epilepsy.

Alterations of Coherent Theta and Gamma Network Oscillations as an Early Biomarker of Temporal Lobe Epilepsy and Alzheimer's Disease

Alzheimer's disease (AD) and temporal lobe epilepsy (TLE) are the most common forms of neurodegenerative disorders characterized by the loss of cells and progressive irreversible alteration of cognitive functions, such as attention and memory. AD may be an important cause of epilepsy in the elderly. Early diagnosis of diseases is very important for their successful treatment. Many efforts have been done for defining new biomarkers of these diseases. Significant advances have been made in the searching of some AD and TLE reliable biomarkers, including cerebrospinal fluid and plasma measurements and glucose positron emission tomography. However, there is a great need for the biomarkers that would reflect changes of brain activity within few milliseconds to obtain information about cognitive disturbances. Successful early detection of AD and TLE requires specific biomarkers capable of distinguishing individuals with the progressing disease from ones with other pathologies that affect cognition. In this article, we review recent evidence suggesting that magnetoencephalographic recordings and coherent analysis coupled with behavioral evaluation can be a promising approach to an early detection of AD and TLE. Highlights -Data reviewed include the results of clinical and experimental studies.-Theta and gamma rhythms are disturbed in epilepsy and AD.-Common and different behavioral and oscillatory features of pathologies are compared.-Coherent analysis can be useful for an early diagnostics of diseases.

Cognition and dementia in older patients with epilepsy

With advances in healthcare and an ageing population, the number of older adults with epilepsy is set to rise substantially across the world. In developed countries the highest incidence of epilepsy is already in people over 65 and, as life expectancy increases, individuals who developed epilepsy at a young age are also living longer. Recent findings show that older persons with epilepsy are more likely to suffer from cognitive dysfunction and that there might be an important bidirectional relationship between epilepsy and dementia. Thus some people with epilepsy may be at a higher risk of developing dementia, while individuals with some forms of dementia, particularly Alzheimer's disease and vascular dementia, are at significantly higher risk of developing epilepsy. Consistent with this emerging view, epidemiological findings reveal that people with epilepsy and individuals with Alzheimer's disease share common risk factors. Recent studies in Alzheimer's disease and late-onset epilepsy also suggest common pathological links mediated by underlying vascular changes and/or tau pathology. Meanwhile electrophysiological and neuroimaging investigations in epilepsy, Alzheimer's disease, and vascular dementia have focused interest on network level dysfunction, which might be important in mediating cognitive dysfunction across all three of these conditions. In this review we consider whether seizures promote dementia, whether dementia causes seizures, or if common underlying pathophysiological mechanisms cause both. We examine the evidence that cognitive impairment is associated with epilepsy in older people (aged over 65) and the prognosis for patients with epilepsy developing dementia, with a specific emphasis on common mechanisms that might underlie the cognitive deficits observed in epilepsy and Alzheimer's disease. Our analyses suggest that there is considerable intersection between epilepsy, Alzheimer's disease and cerebrovascular disease raising the possibility that better understanding of shared mechanisms in these conditions might help to ameliorate not just seizures, but also epileptogenesis and cognitive dysfunction.

Causal inference as an emerging statistical approach in neurology: an example for epilepsy in the elderly

The elderly population faces an increasing number of cases of chronic neurological conditions, such as epilepsy and Alzheimer's disease. Because the elderly with epilepsy are commonly excluded from randomized controlled clinical trials, there are few rigorous studies to guide clinical practice. When the elderly are eligible for trials, they either rarely participate or frequently have poor adherence to therapy, thus limiting both generalizability and validity. In contrast, large observational data sets are increasingly available, but are susceptible to bias when using common analytic approaches. Recent developments in causal inference-analytic approaches also introduce the possibility of emulating randomized controlled trials to yield valid estimates. We provide a practical example of the application of the principles of causal inference to a large observational data set of patients with epilepsy. This review also provides a framework for comparative-effectiveness research in chronic neurological conditions.

Utilization of antiepileptic drugs in Israel

PURPOSE

The aim of the study was to identify trends in utilization of antiepileptic drugs (AEDs) over time in a nation-wide population in Israel.

METHODS

Data on AED utilization (for all indications) for the period 2010-2014 were obtained from pharmaceutical companies that distribute AEDs in Israel. Prevalence of AED utilization was reported as defined daily doses (DDD)/1000 inhabitants/day.

RESULTS

The utilization of most AEDs included in our analysis remained stable over the study period. The greatest increases in utilization of drugs established in Israel were observed for lamotrigine (33%), oxcarbazepine (31%), and primidone (18%). Decreases in use were recorded for carbamazepine (18%) and phenobarbital (15%). Use of older AEDs appeared to be relatively high, compared with the use of newer AEDs.

CONCLUSIONS

During the study period of 2010-2014, conventional AEDs remained a main treatment choice in Israel, in certain cases in contrast to current recommendations and guidelines, for reasons yet to be revealed in further research.

Cognitive deterioration in adult epilepsy: Does accelerated cognitive ageing exist?

A long-standing concern has been whether epilepsy contributes to cognitive decline or so-called 'epileptic dementia'. Although global cognitive decline is generally reported in the context of chronic refractory epilepsy, it is largely unknown what percentage of patients is at risk for decline. This review is focused on the identification of risk factors and characterization of aberrant cognitive trajectories in epilepsy. Evidence is found that the cognitive trajectory of patients with epilepsy over time differs from processes of cognitive ageing in healthy people, especially in adulthood-onset epilepsy. Cognitive deterioration in these patients seems to develop in a 'second hit model' and occurs when epilepsy hits on a brain that is already vulnerable or vice versa when comorbid problems develop in a person with epilepsy. Processes of ageing may be accelerated due to loss of brain plasticity and cognitive reserve capacity for which we coin the term 'accelerated cognitive ageing'. We believe that the concept of accelerated cognitive ageing can be helpful in providing a framework understanding global cognitive deterioration in epilepsy.

The causes of new-onset epilepsy and seizures in the elderly

With increasing age, the prevalence and incidence of epilepsy and seizures increases correspondingly. New-onset epilepsy in elderly people often has underlying etiology, including cerebrovascular diseases, primary neuron degenerative disorders, intracerebral tumors, and traumatic head injury. In addition, an acute symptomatic seizure cannot be called epilepsy, which manifests usually as a common symptom secondary to metabolic or toxicity factors in older people. In this review, we have mainly focused on the causes of new-onset epilepsy and seizures in elderly people. This knowledge will certainly help us to understand the reasons for high incidences of epilepsy and seizures in elderly people. We look forward to controlling epileptic seizures via the treatment of primary diseases in the future.

Shared cognitive and behavioral impairments in epilepsy and Alzheimer's disease and potential underlying mechanisms

Seizures in patients with Alzheimer's disease (AD) have been examined by many investigators over the last several decades, and there are diverse opinions about their potential relevance to AD pathophysiology. Some studies suggest that seizures appear to be a fairly uncommon co-morbidity, whereas other studies report a higher incidence of seizures in patients with AD. It was previously thought that seizures play a minor role in AD pathophysiology because of their low frequency, and also because they may only be noticed during late stages of AD, suggesting that seizures are likely to be a consequence of neurodegeneration rather than a contributing factor. However, clinical reports indicate that seizures can occur early in the emergence of AD symptoms, particularly in familial AD. In this case, seizures may be an integral part of the emerging pathophysiology. This view has been supported by evidence of recurrent spontaneous seizures in transgenic mouse models of AD in which familial AD is simulated. Additional data from transgenic animals suggest that there may be a much closer relationship between seizures and AD than previously considered. There is also evidence that seizures facilitate production of amyloid β (Aβ) and can cause impairments in cognition and behavior in both animals and humans. However, whether seizures play a role in the early stages of AD pathogenesis is still debated. Therefore, it is timely to review the similarities and differences between AD and epilepsy, as well as data suggesting that seizures may contribute to cognitive and behavioral dysfunction in AD. Here we focus on AD and temporal lobe epilepsy (TLE), a particular type of epilepsy that involves the temporal lobe, a region that influences behavior and is critical to memory. We also consider potential neurobiological mechanisms that support the view that the causes of seizures in TLE may be related to the causes of cognitive dysfunction in AD. We suggest that similar underlying mechanisms may exist for at least some of the aspects of AD that are also found in TLE.

Epilepsy with onset at over 50 years of age: clinical and electroencephalographic characteristics

Epilepsy in older individuals has an elevated incidence. The objective of the present work was to evaluate the clinical, EEG and brain imaging aspects in patients showing late-onset epilepsy. Fifty-five patients with late-onset epilepsy (older than 50 years) were evaluated. They were composed of two groups according to the onset age of the epilepsy seizure (ES): 51-60 (G51-60) and over 60 (G60+) years. Focal ES predominated although they were less frequent in G60+. The occurrence of status epilepticus was high and more frequent in G60+ whereas seizures in series predominated in G51-60. Symptomatic epilepsy was more frequent and the vascular etiology predominated. Epileptiform activity was associated with a greater number of ES, and background activity abnormalities were more frequent in G60+. In conclusion, epilepsy with onset at over 50 was predominantly focal and symptomatic, with a high occurrence of status epilepticus and of seizures in series.