Crime in Huntington's disease

OBJECTIVES—To clarify the clinical andneuropsychological aspects of transient epileptic amnesia (TEA) basedon 10 personally studied cases as well as review of 21 previouslypublished cases; and to propose tentative diagnostic criteria for thediagnosis of TEA.
METHODS—All 10 patients and informants underwent astandardised clinical interview. The radiological andneurophysiological (EEG) data were also reviewed in all cases. Thediagnosis of transient epileptic amnesia was made on the basis of thefollowing criteria: (1) there was a history of recurrent witnessedepisodes of transient amnesia; (2) cognitive functions other thanmemory were judged to be intact during typical episodes by a reliablewitness; (3) there was evidence for a diagnosis of epilepsy. Thisevidence was provided by either (a) wake or sleep EEG, or(b) the co-occurrence of other seizure types (if theirroughly concurrent onset or close association with episodes oftransient amnesia suggested a connection), or (c) a clearcut response to anticonvulsant therapy, or by a combination of thesethree factors. In addition all patients were administered acomprehensive neuropsychological test battery designed to assess verbaland non-verbal anterograde memory and retrograde memory for famouspersonalities and personal events. Their results were compared withthose of 25 age and IQ matched normal controls.
RESULTS—TEA usually begins in later life, with amean age of 65 years in this series. Episodes are typically brief,lasting less than one hour, and recurrent, with a mean frequency ofthree a year. Attacks on waking are characteristic. Repetitivequestioning occurs commonly during attacks. The anterograde amnesiaduring episodes is, however, often incomplete so that patients maylater be able to "remember not being able to remember". The extentof the retrograde amnesia during attacks varies from days to years.Most patients experience other seizure types compatible with an originin the temporal lobes, but transient amnesia is the only manifestation of epilepsy in about one third of patients. Epileptiform abnormalities arising from the temporal lobes are most often detected on interictal sleep EEG. Despite normal performance on tests of anterograde memory,many patients complain of persistent interictal disturbance ofautobiographical memory, involving a significant but variable loss ofrecall for salient personal episodes. The epochs affected may predatethe onset of epilepsy by many years.
CONCLUSIONS—TEA is an identifiable syndrome andcomprises episodic transient amnesia with an epileptic basis, withoutimpairment of other aspects of cognitive function. Future studiesshould consider the question of whether TEA reflects ictal activity ora postictal state, and the mechanism of the persistent autobiographicalamnesia. It is hypothesised that the latter may result in part fromimpairment of very long term memory consolidation as a result ofepileptic activity in mesial temporal structures.