After most complex partial and all tonic-clonic seizures, memory is impaired for a period of time. Is it coincidence that impaired anterograde memory is a common interictal cognitive disorder? Do postictal symptoms predict future interictal symptoms? Postictal psychosis may evolve into interictal psychosis (1). Personal observation also suggests that in some patients without prior psychiatric history, periods of postictal depression develop and are followed years later by severe interictal depression. Can treatment of seizures and postictal symptoms provide an opportunity for prevention?

Romberg (2) (1853) recognized that memory impairment was the most common interictal disorder. Patients complain of impaired recall for recently learned information, especially details and names. Left temporal seizure foci (partial seizure disorder arising from left temporal lobe) impair mainly verbal memory, and right temporal foci impair recently acquired visual, spatial, and geographic memory. Although patients with TLE show memory impairments on 30-minute delayed-recall tests, longer delays demonstrate even greater impairment (3). As in other cognitive disorders, several factors contribute to interictal amnesia, including structural lesions (physical abnormalities in the brain, such as a stroke, scar, tumor, etc)(4), neuronal dysfunction or loss, interictal epileptiform discharges (5), recurrent seizures, and antiepileptic drugs (6–8). Interictal hypometabolism marks hypofunction, correlating with impaired memory when it involves the medial temporal memory structures (9).

Treatment of interictal memory disorders
How do we treat interictal memory disorders? Improved seizure control, reduction or elimination of AEDs that adversely affect cognition (e.g., phenobarbital, topiramate) (10,11), and better sleep habits improve memory in some patients. Pragmatic approaches include use of visual imagery, lists and schedules (displayed prominently), learning to take simple and clear notes, small portable notepads organized by topic, carrying important telephone numbers and addresses, and use of alarms as reminders. These strategies often fail to fulfill the needs of higher-functioning patients with demanding jobs. No medications are proven to enhance memory in patients with epilepsy (12).

Phytomedicinal extracts from Ginkgo biloba leaves are used as dietary supplements. The main active compounds in the leaves are flavonoid glycosides and ginkgolides. Although uncontrolled studies show improved memory function in demented and elderly subjects, controlled studies do not demonstrate efficacy (13,14). The only safety concern with ginkgo is a possible increase in the risk of bleeding, especially in patients taking warfarin (15).

References

1. Tarulli A, Devinsky O, Alper K. Progression of postictal to interictal psychosis. Epilepsia 2001;42:1468–71.
2. Romberg H. A manual of the nervous diseases of man. Sieveking EH, trans-ed. London, England: Sydenham Society, 1853:203.
3. Blake RV, Wroe SJ, Breen EK, McCarthy RA. Accelerated forgetting in patients with epilepsy: evidence for an impairment in memory consolidation. Brain 2000:123:472–83.
4. Pulliainen V, Kuikka P, Jokelainen M. Motor and cognitive functions in newly diagnosed adult seizure patients before antiepileptic medication. Acta Neurol Scand 2000;101:73–8.
5. Aarts JHP, Bimmin CD, Smit AD, Wilkins AJ. Selective cognitive impairment during focal and generalized epileptiform EEG activity. Brain 1984;107:293–308.
6. Smith DB. Anticonvulsants, seizures and performance. In: Trimble MR, Reynolds EH, eds. Epilepsy, behaviour and cognitive function. New York: Wiley, 1988:67–78.
7. Devinsky O. Cognitive and behavioral effects of antiepileptic drugs. Epilepsia 1995:36(suppl 2):S46–65.
8. Drane DL, Meador KJ. Epilepsy, anticonvulsant drugs and cognition. Baillieres Clin Neurol 1996:5:877–85.
9. Henry TR. Functional neuroimaging with positron emission tomography. Epilepsia 1996:37:1141–54.
10. Lee S, Sziklas V, Andermann F, et al. The effects of adjunctive topiramate on cognitive function in patients with epilepsy. Epilepsia 2003;44:339–47.
11. Devinsky O. Cognitive and behavioral effects of antiepileptic drugs. Epilepsia 1995;36(suppl 2):S46–65.
12. Shulman MB, Barr W. Treatment of memory disorders in epilepsy. Epilepsy Behav 2002;3(5S):30–4.
13. Van Dongen MC, Van Rossum E, Kessels AG, Sielhorst HJ, Knipschild PG. The efficacy of ginkgo for elderly people with dementia and age-associated memory impairment: new results of a randomized clinical trial. J Am Geriatr Soc 2000;48:1183–94.
14. Moulton PL, Boyko LN, Fitzpatrick JL, Petros TV. The effect of Ginkgo biloba on memory in healthy male volunteers. Physiol Behav 2001;73:659–65.
15. Heck AM, DeWitt BA, Lukes AL. Potential interactions between alternative therapies and warfarin. Am J Health Syst Pharm 2000;57:1221–7.

Reproduced and adapted with permission from Orrin Devinsky, M.D. and Epilepsia.

Topic Editor: Steven C. Schachter, M.D.
Last Reviewed:7/26/04