Epidemiology and drug treatment of epilepsy in elderly people

Seizures are extremely common in the elderly, with an annual incidence reac hing 100 per 100 000 people aged over 60 years. Most are precipitated by ac ute symptomatic illnesses such as stroke or systemic disease. Chronic neuro logical diseases such as Alzheimer's disease may also cause seizure. The ae tiology of seizures in many patients is unknown. Seizures may be situationa l 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 on set, especially complex partial. Complex partial seizures at this age may b e very subtle and hard to diagnose. Generalised-onset seizures also occur, perhaps as a result of diffuse changes with aging or degenerative disease o r 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 lend to a need for gentler drug tre atment with cautious initiation of drugs at lower dosages. Consideration mu st be given to renal and hepatic function. protein binding and drug interac tions. Determinations of free (unbound) drug concentrations are helpful for highly protein bound drugs. The dosages of newer drugs excreted renally mu st be adjusted based on creatinine clearance. The dosage of most drugs is d etermined empirically by careful observation of seizure control and adverse effects. Carbamazepine, valproic acid (sodium valproate). gabapentin and l amotrigine have certain theoretical advantages, hut comparative trials of a nticonvulsants in the elderly are needed. The ideal drug for older patients would be effective, without neurological toxicity. with low protein bindin g, a nonparticipant in drug interactions and amenable to once daily adminis tration.