Exploring mental status in Friedreich's ataxia: a combined neuropsychological, behavioral and neuroimaging study.

Despite much evidence of cognitive and affective disorders in Friedreich's ataxia (FRDA), the nature of mental status in FRDA has received little systematic attention. It has been proposed that the cerebellum may interfere indirectly with cognition through the cerebello-cortical loops, whereas the role of pathological changes in different areas of the central nervous system is still undetermined. In the present study, 13 patients with molecularly determined FRDA and a group of matched controls were evaluated by a comprehensive battery of neuropsychological tests and the Minnesota Multiphasic Personality Inventory. A repetitive task of simple visual-reaction times was used to investigate implicit learning in all subjects. Pathological changes in cortical areas were explored comparing cerebral activations of patients and controls during finger movements (functional MRI). The intelligence profile of FRDA patients is characterized by concrete thinking, poor capacity in concept formation and visuospatial reasoning. FRDA patients show reduced speed of information processing. The learning effect seen in controls was notably absent in patients with FRDA. The patients' personality is characterized by some pathological aspects and reduced defensiveness. Patterns of cortical activation during finger movements are heterogeneous in patients compared to controls. Cognitive impairment, mood disorders and motor deficits in FRDA patients may be the result of the cumulative damage caused by frataxin deficiency not only in the cerebellum and spinal cord but also in other brain areas.

Memory deficits and retrieval processes in ALS.

Subtle neuropsychological deficits have been described in patients affected by amyotrophic lateral sclerosis (ALS) without dementia. Overall, selective impairment in memory function has been reported, but the source of memory impairment in ALS has yet to be defined. We performed neuropsychological screening in 20 ALS patients. Semantic encoding and post-encoding cue effects on the retrieval of word lists were investigated in the ALS patients and normal controls. Severity of memory impairment was correlated to cerebral blood perfusion detected by single photon emission computed tomography (SPECT). ALS patients showed moderate impairments in frontal and memory tests. Short-term memory was normal, while serial position retrieval of word lists with normal recency effect but poor primacy effect showed long-term memory deficit. ALS patients performed better in cued encoding than in cued post-encoding recall condition. In the cued post-encoding condition, the primacy effect in word list recall improved significantly in controls, but not in ALS patients, as compared with both the free recall and cued encoding conditions. SPECT hypoperfusion was observed in frontal and temporal areas in ALS patients. ALS patients showed a long-term memory deficit which did not improve in cued post-encoding condition as it does for controls. We hypothesize abnormal retrieval processes related to frontal lobe dysfunction which entails difficulties in generating stable long-memory traces at encoding.

The breakdown of calculation procedures in Alzheimer's disease.

The study investigates calculation abilities in 12 patients with probable Alzheimer's disease (AD) and compares them to calculation abilities of healthy control subjects (NC) and patients with focal left hemisphere lesions (LHL). AD patients scored significantly lower than NC in all calculation tasks and lower than LHL patients in the execution of complex written calculation, but not in the retrieval of arithmetic facts. In the AD group a subject-by-subject error analysis on the complex written calculation showed a low consistency and a high variability of error types. It is suggested that AD patients' difficulties in complex calculation arise from a monitoring deficit and not from incomplete or distorted calculation algorithms. Overall, deficits in monitoring calculation procedures may be an early and common symptom of AD.

Temporal gradient in confabulation.

We report on a patient, PL, who developed an amnesic confabulatory syndrome following heart arrest. PL's confabulation occurred both in episodic and semantic memory tasks. In a task in which she was asked to identify photographs of people and events highly familiar to her, a temporal gradient on her performance emerged. Confabulation was massive for the recognition of photographs from the eighties and decreased consistently for the recognition of photographs representing people and events from earlier decades. Correct responses, in contrast, were distributed according to an opposite pattern. Correct recognition was very high for photographs from the fifties but consistently decreased for photographs from the following decades. These results are discussed in terms of the co-occurrence and interaction of preserved awareness of the personal past and impaired ability to access less stable memories. These results also suggest that memories are not stored randomly but according to a temporal criterion that presumably reflects the relative strength and stability of stored episodic memories.

Limb-kinetic apraxia.

Five cases of limb-kinetic apraxia following primary degenerative cerebral pathology are reported. Apraxia appeared as the main symptom and was not concomitant to aphasia or to widespread cognitive impairments. Apraxia was not a consequence of elementary motor or sensory deficits, lack of coordination, or the result of the presence of rigid-akinetic symptoms. The apraxia was usually unilateral, being present in both routine activities and testing sessions and consisting of the coarse, unilateral, awkward execution of correctly planned movements. Conceptual knowledge of the movements and their ideational plan was spared. The characteristics of apraxia fit the definition of limb-kinetic apraxia originally proposed by Liepmann. The pertinent literature is reviewed.

Morphological and functional study of a case of superficial siderosis of the central nervous system.

We here describe a case of superficial siderosis (SS) of the central nervous system (CNS), occurring in a patient with a previous lesion of the brachial plexus. Of the only 96 cases that have been described in the literature so far, there are now five with a positive history of a lesion due to the evulsion of the roots of the brachial plexus. This is the first time that, in addition to CT and MRI morphological investigations, an SS patient has also been studied metabolically by means of PET in an attempt to find new clues that may help to clarify the pathogenesis of the disease.

Remembering and knowing the past: a case study of isolated retrograde amnesia.

We describe a patient, RM, who suddenly became amnesic for premorbid autobiographic events in the absence of any known precipitating event. Learning abilities as well as semantic knowledge were normal. Knowledge of famous facts and persons was good, although not perfect. Whether RM suffered from organic or psychogenic isolated retrograde amnesia (IRA) could not be established on the basis of available clinical and neuropsychological elements. Regardless of its aetiology, RM's case respects the boundaries between semantic and episodic memory and so gives further support to the distinction between these two memory systems.

Semantic and episodic memory in aphasia.

Within the framework of the distinction between episodic and semantic memory, it has been argued that these two memory Systems are organised in a hierarchical way. The hierarchical hypothesis assumes that episodic memory is a specific subsystem of semantic memory and therefore implies that episodic memory cannot exist without semantic memory. If this hypothesis is correct, it should be expected that (episodic) yes/no recognition performance would improve in patients with preserved semantic memory, following semantic encoding. In the present study we investigated the influence of semantic encoding on recognition memory performance in a population of 28 aphasic patients (AA) and 14 normal controls (NC). Experiment 1 considered recognition memory for semantically unrelated items, whereas Experiments 2 and 3 assessed recognition memory for semantically related items. In Experiment 3, but not in Experiment 2, subjects were explicitly instructed to make a semantic association between the items. AA were impaired, compared to NC, only on the recognition memory performance of Experiment 1. The ability to make a semantic association between two items was significantly and positively correlated to the ability to recognise, in a subsequent test, those same items. A further analysis showed that patients who were impaired on the semantic association task did significantly worse on the recognition task of Experiment 3 than NC and than patients who were unimpaired on the semantic association task. These findings are discussed in the context of memory deficits in aphasia and interpreted as giving support to the view that episodic memory for an item is affected by the level of semantic awareness of that same item.

Anomia for people's names.

The case of an anomia for people's names is reported. The study of this dissociation helps to clarify the difference in processing between proper and common names. Associated deficits in this and previously described cases provide support for the idea that an inability to retrieve arbitrary relations is the basis of the naming difficulty. This would confirm the role of proper names as purely referring expressions.