**Author details**

163]. The ability to identify changes in cortical structure or function very early in the devel‐ opment of AD would increase the efficacy of treatments that stop the progression of the neurodegeneration before a significant amount of cortex is lost [62]. Neuroimaging measure‐ ments of VFM changes in patients with mild AD may provide an avenue for such early diagnosis, as these measurements can reveal subtle and highly detailed cortical changes using non-invasive fMRI [37]. In addition, these measurements in individual subjects also provide the opportunity to follow neurodegenerative changes in specific individuals over the course of their dementia progression (e.g., [9]). Further research into VFM characteristics in AD should include not only a larger population of AD patients, but also should examine the potential onset of visual symptoms in patients with mild cognitive impairment (MCI), which may

Disagreement also persists regarding the categorization of neurodegenerative symptoms into specific types of dementia. We do not yet have a complete understanding of how the different types of dementia—e.g., AD, PCA, DLB, etc.—vary with respect to the start of their associated neurodegenerative changes. Criteria have been outlined to differentiate AD from other dementias, but there still remains significant overlap across the symptoms associated with each dementia (e.g., [56, 78, 85, 86, 165]). The ability to distinguish a patient's particular type of dementia at an early time point in the disease may be vital for the identifying the correct treatment. Such comprehensive measurements of alterations in VFM characteristics as discussed here may assist in this early identification and diagnosis, as the onset and severity of changes in visual cortex are expected to follow patterns specific to each particular dementia

Systematic changes in visual cortex likely occur as part of both the normal aging process and the pathophysiology of AD. A better understanding of the alteration of visual representations during healthy aging would both help reveal the effects of healthy aging on visual processing and enhance the use of age-matched controls in studies of visual symptoms in age-related diseases [57, 132]. Our hope is that such data will contribute to earlier and more definitive detection of these forms of dementia and a better understanding of the differences between

This work was supported in part by the National Institutes of Health Loan Repayment Program award #L30 EY019249 to A.A.B. and by the pilot grant to A.A.B. from the MIND Institute and Alzheimer's Disease Research Center at the University of California, Irvine, supported by the

provide an even earlier diagnostic tool [37, 55, 154, 164].

[37].

298 Update on Dementia

**5. Conclusion**

AD and related dementias.

**Acknowledgements**

National Institutes of Health grant #AG16573.

Alyssa A. Brewer\* and Brian Barton

\*Address all correspondence to: aabrewer@uci.edu

Department of Cognitive Sciences, University of California, Irvine, CA, USA
