Blog #164: MEMORY: SUBJECTIVE COMPLAINTS VS ACTUAL OBJECTIVE DEFICITS IN EPILEPSY

 

 

Who amongst us doesn’t find fault with our own memory? But are memory concerns and complaints due to actual brain pathology or are they within the normal age-spectrum? Over half of patients with epilepsy complain of impaired memory. Are they actual memory deficits, though? We know that anticonvulsant medications commonly have deleterious effects on memory as can depression, other medications and illnesses.

Exploring memory researchers recruited patients with Temporal Lobe Epilepsy (TLE).¹ TLE diagnosis was based on abnormal EEG and clinically typical seizures. Our temporal lobes are where memory is generated and preserved. Damage there does affect memory whereas damage to other parts of the brain does not have as serious effects on memory. Generalized epilepsy, which does not focus on temporal lobes, seems to have less deleterious effects on memory as compared with TLE.

Researchers recruited 47 patients with TLE. Age and sex-matched 35 healthy controls were similarly studied. Self-evaluation memory questionnaires were used to assess the magnitude of memory complaints. All were then studied with neuropsychological examinations. A surprise recall testing 3 weeks later occurred. No significant differences on standard testing were found between the performance of patients and controls.

The two groups were then brought back three weeks later. The surprise recall tests 3 weeks later revealed significant differences between the two groups. They were assessed if they recalled simple events that occurred during that original testing 3 weeks before. For example, was there a memory of a water glass being offered? Did the examiner leave the room and change what they wore? Did the subject recall the phone ringing twice during the visit, or recall being asked to retrieve a questionnaire from a shelf, etc.? In the absence of spontaneous recall without cues, cues were then provided by the researchers followed by recognition questions such as “did the phone ring once or twice? Were you offered water etc.? Scores were generated.

The standard neuropsychological battery we have relied on to test cognition and memory has some blind spots; an adequate assessment of autobiographical memory and our “long term” memory assessments occur 10 to 30 minutes after the information is encoded. Traditionally these tests haven’t been performed. It is these blind spots that have been addressed in this study. People with subjective memory complaints that were corroborated by family members had normal performance on standard neuropsychological testing. But scores 3 weeks later were significantly lower in the epilepsy group.

This information is another reminder that we need to listen closely to our patients’ complaints, and that our gold standards need to be updated as our understanding of memory evolves.

1)     Lemesle B, Barbeau EJ, Milongo Rigal E, et al. Hidden objective memory deficits behind subjective memory complaints in patients with temporal lobe epilepsy. Neurology. 2022;98(8): E818-E828

 

Lance Fogan, M.D. is Clinical Professor of Neurology at the David Geffen School of Medicine at UCLA. His hard-hitting emotional family medical drama, “DINGS, is told from a mother’s point of view. “DINGS” is his first novel. Aside from acclamation on internet bookstore sites, U.S. Report of Books, and the Hollywood Book Review, DINGS has been advertised in recent New York Times Book Reviews, the Los Angeles Times Calendar section and Publishers Weekly. DINGS teaches epilepsy and is now available in eBook, audiobook, soft and hard cover editions.