Verbal memory impairments in dyslexia.

Although verbal memory deficits are frequently reported in reading disabled children, the specific mechanisms underlying these impairments have yet to be clearly defined. The present study used the California Verbal Learning Test-Children's Version (CVLT-C) to assess verbal learning in 57 dyslexic children and 114 controls matched for gender, age, and WISC-R Vocabulary score. Three areas of verbal memory were investigated: Recall and recognition, use of learning strategies, and interference effects. The dyslexic group learned the list items more slowly, recalled fewer words on the last learning trial and the delayed trials, and performed less well on the recognition condition. Dyslexics and controls displayed similar vulnerability to interference, but group differences were evident in serial position effects. Taken together, our data suggest that dyslexics have less efficient rehearsal and encoding mechanisms, resulting in deficient encoding of new information, but normal retention and retrieval.

Olfaction in persons with Alzheimer's disease.

The need for low cost, noninvasive procedures for aiding in the diagnosis and understanding of Alzheimer's Disease (AD) has led to theories and procedures examining the role of olfactory disorders because of the finding that the brains of AD patients invariably exhibit neuropathology in the hippocampus and entorhinal cortex. This loss correlates with the increase in the number of plaques and tangles and with the severity of dementia. Considered together, these findings suggest that brain structures closely related to the olfactory system demonstrate significant histopathology in AD. A comprehensive review of the literature pertaining to olfaction in persons with AD revealed that the olfactory identification ability of patients with memory disorders is impaired relative to controls. Consistency is lacking, however, when olfactory detection thresholds are investigated. Also, there is inconsistency in regards to severity of illness and olfactory function. In addition to differentiating AD patients from normals, the olfactory paradigm has shown some limited usefulness in differentiating AD patients from some other demented patients.

Impaired depth perception discriminates Alzheimer's dementia from aging and major depression.

Parietal and temporal lesions are known to impair binocular depth perception. Clinically meaningful impairment was therefore suspected due to early degeneration of these regions in Alzheimer's dementia. Results supported the cortical localization described in focal lesion studies. Deficient stereopsis was common in dementia (80%) but relatively uncommon in elderly normals (14%) and major depressives with cognitive symptoms (31%). Performance was unrelated to age, IQ, or severity of cognitive impairment. Testing involves minimal patient effort and time (1-2 min). Stereopsis examination may be useful in the diagnosis of early dementia, and may reduce false positives associated with depression, limited premorbid ability, or normal aging.