Fourteen patients with spinocerebellar ataxia 1 (SCA1) and 11 controls with similar mean age and IQ estimates were submitted to a neuropsychological test battery comprising tests for IQ, attention, verbal and visuospatial memory as well as executive functions. Neuropsychological assessment yielded verbal memory and executive dysfunction while tests of visuospatial memory and attention were not significantly impaired in SCA1 as compared to controls. Test performance was neither related to the repeat length, the age of onset nor the disease duration. The profile of cognitive impairment in SCA1 with prominent executive dysfunction corresponds to the concept of ‘frontal-subcortical’ dementia that is likely to be contingent upon disruption of a cerebrocerebellar circuitry that consists of afferent and efferent connections between the prefrontal cortex and the cerebellum.

No abstract

Lower limb areflexia is generally regarded as an essential criterion for the diagnosis of Friedreich's ataxia (FRDA). We describe a family with a recessive form of early-onset ataxia in which one member had a phenotype typical of FRDA whereas another, with retained tendon reflexes in the lower limbs, did not have electrophysiologic evidence of the usual severe afferent axonal neuropathy of FRDA. In contrast, somatosensory evoked potentials, eye-movement recordings, and MRI of the head and cervical cord provided results highly suggestive of FRDA in both patients. We performed genetic linkage analysis in this family, using markers tightly linked to the FRDA locus on chromosome 9. Inheritance of identical paternal and maternal genotypes by the affected members, but not by their unaffected siblings, provided supporting evidence that this disorder may result from mutation within the FRDA gene or is tightly linked to the investigated loci on chromosome 9.

The aim of this study was to assess cognitive function in patients with spinocerebellar ataxia type 6 (SCA6), an autosomal-dominantly inherited disease leading to a progressive cerebellar syndrome. In contrast to other SCA types, the pathological changes are mostly restricted to the cerebellum. Cognitive function was studied in 12 patients with genetically confirmed SCA6 (mean duration of disease: 9.2 +/- 11.6 years) and 12 age- and IQ-matched controls using a test battery comprising tests for IQ, attention, verbal and visuospatial memory, as well as executive function. While none of the SCA6 subjects had features of general intellectual impairment, only mild deficits in single subtests especially in fronto-executive tasks were observed, but without reaching statistical significance. Thus the current findings do not demonstrate severe cognitive dysfunction in SCA6.

The somatic mosaicism for expanded repeats observed in FRDA patients rendered the precise measurement of allele sizes more difficult and may influence the results of studies correlating the clinical spectrum with the genotype. Following, a confidential prediction of the prognosis deduced from the repeat length is hardly possible for an individual FRDA patient.