Dissociative Amnesia and the Future of Forensic Psychiatric Assessment
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Commentary: Dissociative Amnesia and the Future of Forensic Psychiatric Assessment Robert P. Granacher, Jr., MD, MBA J Am Acad Psychiatry Law 42:214–8, 2014 In their article, Pyszora et al.1 present the results of tive defects may be noted on careful neuropsycholog- research in which they re-examined 50 violent of- ical testing.3 fenders from an original case study. In the earlier Dissociative amnesia, on the other hand, as dis- study, they evaluated 59 amnesic violent offenders cussed in DSM-5 describes an inability to recall im- who received a life sentence in 1994 in England and portant autobiographical information (incidental Wales and compared them against a group of memory), usually of a traumatic or stressful nature, nonamnesic offenders (n ϭ 148). In the current fol- which is inconsistent with ordinary forgetting. It of- low-up study, the authors reinterviewed 31 of the ten consists of localized or selective amnesia for a original 59 violent offenders and applied neuropsy- specific event or events. The symptoms cause clini- chological and psychological measures, as noted cally significant distress or impairment in other im- within the body of their research report.2 portant areas of functioning. The disturbance is not Amnesia is the generic term for a severe nondisso- attributable to physiological effects of a substance, a ciative memory deficit, regardless of cause.3 The Di- neurological or other medical condition, or other agnostic and Statistical Manual of Mental Disorders, neurological disease. The disturbance is not better Fourth Edition, Text Revision (DSM-IV-TR)4 gives explained by dissociative identity disorder, posttrau- four clinical characteristics that are typical of most matic stress disorder, acute stress disorder, somatic amnesic patients: anterograde amnesia, retrograde symptom disorder, or major or mild neurocognitive amnesia, confabulation, and intact intellectual func- disorder.5 No methods for measurement or labora- tion. Anterograde amnesia is the hallmark of an am- tory verification of putative dissociative amnesia are nestic disorder and refers to the inability, after the offered in DSM-5. onset of the disorder, to acquire new information for Jean-Martin Charcot6 and Pierre Janet7 are the explicit retrieval. Retrograde amnesia refers to diffi- French neurologists most responsible for providing culty in retrieving events that occurred before the the beginning theories of dissociation. In the era of onset of the amnestic disorder, often demarcated at these two physicians, dissociative disorders were the time of onset by head trauma, stroke, or other studied in great depth and detail, but after 1890, they injury. Retrograde amnesia is more variably present received minimal attention for nearly 80 years. In the in different amnesias. Confabulation does not occur late 1980s and into the 1990s, there was a renaissance in all amnesias, and it is often present only in the of interest. However, virtually no funds were made acute stage. Finally, in the classic amnestic disorders, available for their systematic investigation. Virtually the patient’s intellectual function remains relatively all of the literature with regard to dissociative disor- intact, even though some specific secondary cogni- ders was based on using multiple personality disorder nomenclature. Controlled studies about the basic Dr. Granacher is Clinical Professor of Psychiatry, University of Ken- phenomena of the dissociative disorders were rela- tucky College of Medicine, Lexington, KY. Address correspondence 8 to: Robert P. Granacher, Jr, MD, MBA, 1401 Harrodsburg Road, tively few until the 1990s. The original theories of Suite A400, Lexington, KY 40504. E-mail: [email protected]. Janet were the first to show systematically a direct Disclosures of financial or other potential conflicts of interest: None. psychological defense against overwhelming trau- 214 The Journal of the American Academy of Psychiatry and the Law Granacher matic experiences. He demonstrated that dissociative of new learning (anterograde amnesia) are present, as phenomena played an important role in the widely is a variable retrograde amnesia, usually with a so- divergent posttraumatic stress responses, which were called temporal gradient.13 Preservation of the im- included under the 19th century diagnosis of hyste- mediate memory span is a point of importance clin- ria. His nine concepts of dissociation have been ele- ically. Performance on a test of digit span is usually gantly described elsewhere.9 normal, and therefore this test will fail to reveal the Dissociative amnesia is rarely diagnosed in mod- existence even of a severe amnesic syndrome. More- ern times.3 In the classic hysteria study by Perley and over, current and recent memory (new learning) is Guze,10 symptoms such as dizziness, headache, fa- severely impaired, and disorientation in time is al- tigue, and abdominal pain occurred at high rates in most universal. In the most extreme cases, new learn- more than 70 percent of patients. Amnesia was found ing may be reduced to virtually nil, so that as time in only eight percent of cases. Second, patients with goes by, there is a continuing and extending antero- dissociative amnesia typically have several other psy- grade amnesia. If recovery subsequently occurs, a chiatric disorders or manifest the amnesia after a very dense and permanent gap will be left for the duration stressful trauma. Current nosology excludes a diag- of the illness. In less severe examples, the problem nosis of dissociative amnesia in many such instances. reveals an uncertainty about events that occurred A functional amnesia does not necessarily interfere minutes, days, or weeks before. The retelling of sim- with social or occupational functioning, as noted. ple stories is marked by gross omissions, incorrect Dissociative amnesia is more common among fe- juxtapositions, and condensations of material.13 males, and it is thought to occur more often in ado- There are no similar models for describing or mea- lescents and young adults. Most cases show rapid suring dissociative amnesia accurately. recovery of memory. The classic studies of Ables and The neuropsychiatry of nondissociative amnesic Childer,11 and Herman,12 revealed that in 63 cases of disorders is well delineated at this time in medical dissociative amnesia, 27 individuals recovered within history.14 Three patterns of remote memory impair- 24 hours, 21 within five days, 7 within a week, and 4 ment in amnesic subjects have been described in the within three weeks or more (59/63 cases recovered medical literature. The first is impairment that is within a week). temporally limited, involving primarily the few years From a clinical psychiatric standpoint, the neuro- before the onset of the amnesia, with complete or psychological pattern of deficits seen in classical non- near-complete sparing of more remote time periods. dissociative amnesic states are described in a some- This is documented in the famous amnesic patient, what arbitrary division as immediate, recent, and H. M.15 The second pattern of impairment involves remote memory.13 Immediate memory span is re- a temporal gradient affecting all time periods, with flected in the reproduction of material, such as brief greater impairment of memories derived from recent digit sequences, which fall within the span of atten- periods. This pattern of remote memory disturbance tion. This represents a short-term memory mecha- is said to be typical of patients with alcoholic Korsa- nism. Recent memory is the ability to acquire and koff’s syndrome.16 The third pattern described in the retain new information or knowledge, and it is often medical literature is an impairment affecting all time described as new learning. Clinically, it is assessed by periods equally; it has been described in patients sur- testing for the ability to recall simple information viving herpes simplex encephalitis17 and in certain (exceeding the memory span) after at least a minute other amnesic subjects, as well as in patients with has elapsed. Remote memory is reflected in the abil- Huntington’s disease.18 ity to recall events or facts acquired at a considerable In evaluating the nondissociative amnesic person, distance in time, certainly before the onset of the there are two main goals to meet: establish the sever- claimed memory difficulties. An impairment in re- ity of the memory disorder in the context of other mote memory indicates retrograde amnesia, whereas cognitive complaints; and characterize the nature of the inability to learn new information indicates an- the memory impairment at its basis in encoding, terograde amnesia. storage, and retrieval operations.14 For the first goal, In the classic nondissociative amnesia clinical pic- memory testing should be embedded in a compre- ture, perception is unimpaired, and the immediate hensive mental status and/or neuropsychological ex- memory span is well preserved. Severe impairments amination that includes assessment of general intel- Volume 42, Number 2, 2014 215 Commentary lectual capacity, language functions, visuoperceptual/ ments of their participants. Their problem demon- visuospatial skill, frontal-executive skills, and motor strates the general lack of capacity for forensic psy- functions, including an evaluation of psychopathol- chiatrists to perform a scientific assessment of a claim ogy and emotional dysfunction.14 The second goal is of dissociative amnesia. This handicap in our profes- achieved by assessing memory functions relevant to