The incidence of epilepsy peaks in two periods of life: the first years and old age. New diagnoses of epilepsy rise after the age of 50 and reach their highest level above 75. About one quarter of new-onset seizures occur in people over 60. People over 65 are also the fastest-growing age group in the world. For this reason, epilepsy that begins for the first time in later life (late-onset epilepsy) is becoming increasingly common.
There is no universally accepted definition of late-onset epilepsy. Most studies use the age of 60 or 65 as the threshold. Late-onset epilepsy is not simply the epilepsy of younger people appearing at an older age. Its causes, symptoms and course are different.
Late-onset epilepsy is most often caused by damage the brain has acquired over time. The most common cause is stroke. This is followed by dementias, Alzheimer's disease in particular, brain tumours and head injuries. In 15 to 30 percent of patients, no cause is found. In these patients, too, an undetected vascular disease or neurodegenerative process is thought to be present. Diabetes, hypertension and smoking also increase the risk.
In older people, seizures often do not take their familiar forms. There may be no convulsions and no falling to the ground. Seizures often appear as brief unresponsiveness, absent-mindedness, drowsiness or confusion. Recovery after a seizure may take a long time. It takes even longer in people with pre-existing memory problems. These episodes are easily mistaken for forgetfulness, age-related absent-mindedness or a side effect of medication. Seizures that occur during sleep may go entirely unnoticed.
Transient epileptic amnesia is a condition specific to this age group. The average age at onset is 62. Patients usually experience episodes of memory loss lasting 15 to 30 minutes. These episodes typically occur on waking in the morning and recur about once a month on average. A quarter of patients have no other seizure type. The condition is still under-recognised, although it responds well to treatment.
Diagnostic delay is common. Only one in three patients receives a correct diagnosis of late-onset epilepsy at the first visit. In more than a quarter of patients, epilepsy is never even considered. In one in four patients, the diagnosis is delayed by more than two years. The condition most often confused with it is syncope, a faint caused by a problem with blood pressure or heart rhythm.
In patients with late-onset epilepsy, the likelihood of stroke in the following years increases three- to fourfold. Late-onset seizures with no identifiable cause are also associated with a roughly twofold increase in the risk of dementia. In other words, a seizure with no identifiable cause may be the first sign of another disease progressing silently in the brain. The vascular risk factors and memory function of these patients should be monitored closely.
Late-onset epilepsy responds to medication better than epilepsy in younger people. Fewer than 10 percent of patients develop drug-resistant epilepsy. However, older people are more sensitive to side effects. Many take several medications for other conditions, and these drugs can interact. Treatment is therefore started at a low dose and increased slowly.
