Epidemiology and drug treatment of epilepsy in elderly people.

Seizures are extremely common in the elderly, with an annual incidence reaching 100 per 100000 people aged over 60 years. Most are precipitated by acute symptomatic illnesses such as stroke or systemic disease. Chronic neurological diseases such as Alzheimer's disease may also cause seizures. The aetiology of seizures in many patients is unknown. Seizures may be situational and subside quickly, but the prevalence of chronic seizures--epilepsy--is as high as 1% in the elderly. The majority of seizures are of partial onset, especially complex partial. Complex partial seizures at this age may be very subtle and hard to diagnose. Generalised-onset seizures also occur, perhaps as a result of diffuse changes with aging or degenerative disease or to a combination of genetic and environmental factors. The prognosis for complete seizure control in this population is relatively favourable. Physiological and disease-related changes with aging result in complex pharmacokinetics. Most changes lead to a need for gentler drug treatment with cautious initiation of drugs at lower dosages. Consideration must be given to renal and hepatic function, protein binding and drug interactions. Determinations of free (unbound) drug concentrations are helpful for highly protein bound drugs. The dosages of newer drugs excreted renally must be adjusted based on creatinine clearance. The dosage of most drugs is determined empirically by careful observation of seizure control and adverse effects. Carbamazepine, valproic acid (sodium valproate), gabapentin and lamotrigine have certain theoretical advantages, but comparative trials of anticonvulsants in the elderly are needed. The ideal drug for older patients would be effective, without neurological toxicity, with low protein binding, a nonparticipant in drug interactions and amenable to once daily administration.