Epilepsy is often considered to be a condition of youth, but in fact the highest incidence of new-onset epilepsy occurs in people aged 60 and above, and it is growing rapidly. Yet despite this increasing problem, making an accurate diagnosis of epilepsy in the elderly is challenging, and people currently wait an average of 1.7 years between experiencing initial symptoms and obtaining an official diagnosis and treatment.

Diagnosis is challenging because, although the most common type of epilepsy in this age group is complex partial epilepsy (CPE), it does not have the same features as it does in a younger population with CPE. For example older people with CPE rarely have auras, and they experience a very prolonged period of confusion after a seizure that can last hours, days or even weeks, as opposed to the more typical 5-15 minutes. The only sign of epilepsy might be a disturbance in consciousness followed by a blank stare, or an altered mental state, and these are often attributed to dementia.

Researchers in Texas have carried out a study to identify risk factors associated with epilepsy in the elderly, which may be used to help clinicians give prompt diagnosis and treatment.

Risk factors can be divided into two groups: central nervous system (CNS) risk factors, those that arise in the central nervous system and systemic system (SS) risk factors, those that originate as the result of illness elsewhere in the body. The most recognised CNS disorders associated with new-onset epilepsy in the elderly are cerebrovascular disease (CVD - disease of the blood vessels in the brain), dementia, tumour, and head injury.

Some scientists have recently suggested that CNS microvascular disease (disease of the tiniest blood vessels in the brain) is the cause of epilepsy (in older people) in most cases that are cryptogenic (in which the exact cause is unknown). This is because SS risk factors for CVD, including high blood pressure, high cholesterol, coronary artery disease and disease of the peripheral blood vessels, have been associated with seizures with no obvious sign of damage on brain imaging.

So should SS risk factors for CVD be added to the list of factors for new-onset epilepsy in the elderly? The current study aimed to answer this question.

The researchers used national Department of Veterans Affairs (VA) databases to select people aged 66 and over, who received VA care in its financial years 1999 and 2000 (FY99 and FY00) Those with an official diagnosis of new-onset epilepsy formed the 'epilepsy' group (1,843 people), and those without epilepsy made up the 'geriatric' group (1,023,376 people). Details about each participant's age, sex and race were obtained from the VA databases.

The scientists identified conditions associated with new-onset epilepsy in older people (for example CVD, dementia, and brain tumour) and disorders associated with SS risk-factors (e.g. hypertension, diabetes mellitus, and cardiovascular disease). They then looked at each person's records to see if they had been diagnosed with any of these conditions, either before epilepsy onset (in the case of the epilepsy group) or during FY00 (for the geriatric group). Using advanced analysis techniques, they looked to see if any of the conditions occurred significantly more often in the epilepsy group than in the geriatric group. In these cases, the scientists used special calculations to estimate the risk of epilepsy development carried by these conditions.

The results showed that elderly people with CVD were 350% more likely to develop new-onset epilepsy than those without CVD. For individuals with CVD and dementia, this figure was over 400%. A brain tumour and head injury posed just over twice the risk (214% and 211% respectively) compared to those without these conditions, and other CNS conditions carried a 157% risk.

Surprisingly, people with raised blood cholesterol were found to have a 13% lower risk of developing new-onset epilepsy than those with normal levels. However those who were taking medication to correct their high cholesterol level (statins) appeared to have an even lower risk (36%). Interestingly, individuals in the older age bracket (85 yrs and older) were at a 34% lower risk of developing epilepsy than their younger peers (66-74 yrs).

There is no evidence from this study that SS risk factors for CVD are independent risk factors for new-epilepsy in older people. These results alone are not conclusive, however, and further investigation is needed to rule out this theory.

CVD and a combination of CVD and dementia posed the greatest risk for new-onset epilepsy amidst the people examined, but all CNS 'insults' raised the risk to a certain degree. This suggests that clinicians should not rule new-onset epilepsy out as a possible diagnosis, when an older person with a history of CNS disorders (dementia and or CVD in particular) presents with blank episodes or an altered mental state.

The finding that statins lowered the risk of developing new-onset epilepsy was very unexpected and certainly requires further exploration. If these results are upheld, statins or statin-like drugs could potentially be used to prevent epilepsy in older people in the future.

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