The ability to produce the correct words while speaking is critical for normal social, academic and occupational functioning. As word finding or naming is mediated by the temporal lobe region, naming difficulty is a common complaint and frequent finding in people with dominant temporal lobe epilepsy (TLE). Naming plays a central role in the clinical care of TLE patients, in that naming performance assists in the determination of lateralization and localization of seizure onset, and identification of cortical areas that are essential for naming is the principle technique for identifying language cortex prior to respective surgery. Although naming in epilepsy has received considerable attention, these efforts have been restricted to younger adults. The incidence and prevalence of epilepsy is currently highest, and continues to rise, in the elderly. Thus, the absence of information on naming in older adults with epilepsy presents a growing clinical problem, particularly as aging introduces new concerns overlaid upon existent, epilepsy-related naming difficulty. Specifically, naming decline is also a feature of normal aging and a hallmark symptom of Alzheimer's disease. When an older adult with epilepsy presents with word finding decline, we currently lack both the knowledge and the proper tools to determine whether the decline represents a typical age-related trajectory in epilepsy, the beginning of a more severe degenerative process, or the relatively benign effects of normal aging. Importantly, the answer to this question would have a significant impact on diagnosis, follow up and treatment. Unfortunately currently available naming measures have serious limitations that compromise their utility, including assessment restricted to the visual modality, insensitive performance measures, vocabulary confounds and cultural biases. The proposed project will address these problems by: 1) Developing and standardizing age appropriate auditory naming and complementary, visual naming measures for older adults, and 2) Applying these measures to characterize and distinguish among naming patterns in healthy older adults, older adults with epilepsy, and older adults with mild Alzheimer's disease. We anticipate that results will: a) Provide new clinical and research instruments for thorough and effective assessment of naming in older adults, b) Delineate the trajectory of naming across the age span in epilepsy, c) Generate new insights into temporal lobe mediation of word retrieval in the aging brain, and d) Provide a noninvasive protocol to assist in the differential diagnosis of degenerative and non-degenerative disorders that affect higher cortical function in older adults.
Word finding or 'naming' decline occurs in normal aging, epilepsy and Alzheimer's disease. However, we currently lack the knowledge and the proper tools to determine whether an individual's pattern of naming decline is characteristic of normal aging, epilepsy or Alzheimer's disease. This is important, because accurate classification of the naming decline would significantly influence diagnosis and treatment. This work will: 1) Lead to better understanding of age-related language changes in healthy aging, epilepsy and Alzheimer's disease, 2) Provide clinicians with non-invasive measures to effectively distinguish among naming patterns characteristic of these three groups, and 3) Provide cognitive neuroscientists with more sensitive tools to investigate language changes in healthy aging and in neurological disorders of aging.
