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Objectives: Anecdotal reports suggest that following traumatic brain injury (TBI) retrograde memories are initially impaired and recover in order of remoteness. However, there has been limited empirical research investigating whether a negative gradient in retrograde amnesia-relative preservation of remote over recent memory-exists during post-traumatic amnesia (PTA) compared with the acute phase post-emergence. This study used a repeated-measures design to examine the pattern of personal semantic (PS) memory performance during PTA and within two weeks of emergence to improve understanding of the nature of the memory deficit during PTA and its relationship with recovery., Methods: Twenty patients with moderate-severe TBI and 20 healthy controls (HCs) were administered the Personal Semantic Schedule of the Autobiographical Memory Interview. The TBI group was assessed once during PTA and post-emergence. Analysis of variance was used to compare the gradient across lifetime periods during PTA relative to post-emergence, and between groups., Results: PS memory was significantly lower during PTA than post-emergence from PTA, with no relative preservation of remote memories. The TBI group was still impaired relative to HCs following emergence from PTA. Lower overall PS memory scores during PTA were associated with increased days to emerge from PTA post-interview., Conclusions: These results suggest a global impairment in PS memory across lifetime periods particularly during PTA, but still present within 2 weeks of emergence from PTA. PS memory performance may be sensitive to the diffuse nature of TBI and may, therefore, function as a clinically valuable indicator of the likely time to emerge from PTA. (JINS, 2018, 24, 1064-1072).

Patients with mild to moderate Alzheimer's disease and normal controls were tested on a retrograde amnesia test with semantic content (Neologism and Vocabulary Test, or NVT), consisting of neologisms to be defined. Patients showed a decrement as compared to normal controls, pointing to retrograde amnesia within semantic memory. No evidence for a gradient within this amnesia was found, although one was present on an autobiographic test of retrograde amnesia that had a wider time scale. Several explanations for these results are presented, including one that suggests that extended retrograde amnesia and semantic memory deficits are in fact one and the same deficit.

Studies have consistently found that patients with multiple sclerosis (MS) are impaired on tests of anterograde memory, but the status of remote memory in MS remains unclear. To better understand remote memory in MS we administered the Autobiographical Memory Interview (AMI) to 44 MS patients and 19 normal controls matched for age, education, and gender. Additionally, a shortened version of the Famous Faces Test, a test of recall of past U.S. presidents, and a 14-word learning list were administered. Patients performed significantly lower than controls on the learning list and Famous Faces Test, but not on recall of past presidents. On the AMI, patients were significantly impaired on recall of semantic but not of episodic memories. These results indicate that MS patients exhibit retrograde amnesia that cannot be attributed to anterograde memory deficits or lack of exposure to task-relevant information.

We studied the recovery of memory and executive function in 10 patients following anterior communicating artery aneurysm (ACoA) rupture and repair. Patients were tested at 2 consecutive points in time following surgery (approximately at 2 and 3 months). At the first testing, the patients divided into 2 groups based on the severity of impairment on executive measures. Both groups had severe anterograde amnesia, but only patients with severe executive impairments had retrograde amnesia with a temporal gradient. At second testing, both groups had persistent severe anterograde amnesia. The dysexecutive group showed significant improvement in executive deficits and in retrograde amnesia, with attenuation of the temporal gradient. Patients with more severe executive impairments had more extensive bilateral frontal lesions than other patients. These results suggest that the cognitive profile following ACoA rupture changes with time. Time postonset following aneurysm rupture and lesion site are both critical for defining the neuropsychological profile, and determining the underlying cognitive mechanisms in this neurological disorder.

There have been few studies of psychogenic amnesia based on a cognitive or neuropsychological framework. In the present study, a patient with acute onset of profound psychogenic retrograde amnesia was examined. Although her performance on neuropsychological tasks revealed intact anterograde memory, language functioning, visuospatial and constructional skills, and mental speed and flexibility, she displayed severe impairments on a variety of retrograde memory tasks. Furthermore, initial observations revealed inconsistencies between the patient's recall of semantic knowledge on direct questioning and her ability to demonstrate the use of this knowledge on indirect tasks. To test this formally, we devised an indirect remote knowledge task to examine a possible dissociation between explicit and implicit memory. Two healthy subjects matched for age, gender, education, occupation, and estimated IQ were also tested. As predicted, the findings demonstrate implicit knowledge despite impaired explicit recall for the same material.

To assess if amnesics have intact remote memory for general semantic information, we examined memory for vocabulary words with known dates of entry into the language between 1955 and 1989. Amnesics of mixed etiology with acute onset performed normally on both a recall and a recognition task. Korsakoff patients, in contrast, were impaired on both tasks and demonstrated a gradient such that their knowledge of words acquired during more recent time periods was worse than that of words acquired during more remote time periods. The improvement in performance associated with recognition testing was larger for Korsakoff patients than for control subjects and correlated significantly with a composite measure of frontal dysfunction. These findings suggest a deficit in the controlled search and retrieval of semantic information in Korsakoff patients. The implications of the differential performance of Korsakoff and mixed etiology amnesics for explanations of temporally graded retrograde amnesia are discussed.