Association between dysarthria and cognitive impairment in ALS: A prospective study.

Several studies have demonstrated impaired cognition in amyotrophic lateral sclerosis (ALS) patients, but it has been difficult to identify risk factors for this impairment. An association between cognitive changes and bulbar site of onset or dysarthria has been suggested, but the findings are variable. We tested for both associations in a large cohort of ALS patients. At the time of diagnosis of sporadic ALS, all patients (n=355) in this prospective study underwent comprehensive neuropsychological testing. In addition, a subset of 175 patients underwent a detailed assessment of dysarthria, which was quantified using the Appel ALS Score (AALSS). ALS patients with bulbar site of onset performed significantly worse than limb onset patients on a few timed ((VSAT-time, p<0.05), (Stroop Color, p<0.05), (Stroop Word, p<0.05)) tests of frontal lobe functions, but the significance could not be replicated when motor impairment was accommodated into the tests ((VSAT-errors, p=0.73), (Stroop interference, p=0.08)). ALS patients with dysarthria performed significantly worse than non-dysarthrics on multiple timed ((BD, p<0.05), (VSAT-time, p<0.05), (Stroop Color, p<0.05), (Stroop Word, p<0.05), (Trails A, p<0.05), (Trails B, p<0.05)) neuropsychological tests, and the significance was maintained when motor impairment was accommodated into one of these tests (Stroop interference, p<0.05). Additionally, dysarthrics performed significantly worse on two untimed measures of cognition ((Similarities, p<0.05), (Rey Copy, p<0.05)). Cognitive functioning in ALS does not associate with the site of onset and has a moderate association with dysarthria.

Functional anatomy of human odor sensation, discrimination, and identification in health and aging.

Aging of cerebral olfactory regions was studied in 5 younger and 6 older healthy adults, matched by odor discrimination and identification scores, with positron emission tomography during odor sensory stimulation, discrimination, and identification tasks. Sensory stimulation engaged bilateral piriform and orbitofrontal regions, but neither discrimination nor identification evoked added temporal or orbital activity. Discrimination involved the hippocampus, implicating its role in serial odor comparisons (olfactory working memory). Left inferior frontal activity during identification may reflect semantic associations. Older participants deactivated the left gyrus rectus/medial orbital gyrus (GR/MOG) during sensory stimulation but activated GR/MOG during discrimination and identification. Adjusting for detection threshold eliminated GR/MOG group differences during sensory stimulation. Diminished threshold may lead to reduced engagement of olfactory association areas.