title: Optical Coherence Tomography Reveals Retinal Neuroaxonal Thinning in Frontotemporal Dementia as in Alzheimer's Disease.
abstract: Alzheimer's disease (AD) and frontotemporal dementia (FTD) are leading causes of cognitive decline. Optical coherence tomography (OCT) allows the measurement of thickness of retinal neuroaxonal layers. While in AD and mild cognitive impairment (MCI), retinal nerve fiber layer (RNFL) thinning is frequently reported, less information is available on ganglion cell layer-inner plexiform layer (GCL-IPL). Data on FTD are lacking.
  
  
  
  To obtain cross-sectional information on RNFL and GCL-IPL thickness among MCI, AD, FTD, and healthy controls (HC), and their correlations with dementia severity.
  
  
  
  Peripapillary OCT scans were obtained in 27 MCI, 39 AD, 17 FTD, 49 HC using high-definition Heidelberg Spectral-domain OCT, with RNFL and GCL-IPL thickness measurement. Statistical analysis tested group effects and correlation with gender, disease duration and severity (Mini-Mental State Examination, MMSE).
  
  
  
  RNFL showed a significant group effect [F(4,132) = 3.786, p = 0.006], being reduced versus controls in MCI (p = 0.033), moderate AD (p = 0.025), and FTD (p < 0.001), and versus mild AD in FTD (p = 0.042). GCL-IPL showed a significant group effect as well [F(4,121) = 5.104, p < 0.001], with reduction in moderate AD versus HC (p < 0.001), MCI (p = 0.037), and mild AD (p = 0.009); in FTD versus HC (p = 0.002) and mild AD (p = 0.038). In AD, GCL-IPL correlated with MMSE (r = 0.487, p = 0.003), without significant effects of age, gender, or disease duration.
  
  
  
  Retinal neuroaxonal thinning occurs in MCI/AD consistently with previous reports, as well as in FTD. Correlation with disease severity in AD suggests that retinal and brain neurodegeneration may occur in parallel to some extent, and prompts larger studies aimed at providing surrogate endpoints for clinical trials in AD.
authors.affiliation: Department of Neurology and INSPE - Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Ferrari
authors.affiliation: University Vita-Salute San Raffaele Milan, Italy.
authors.forename: Su-Chun
authors.initials: SC
authors.lastname: Huang
authors.affiliation: Department of Neurology and INSPE - Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Magnani
authors.affiliation: University Vita-Salute San Raffaele Milan, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ambrosi
authors.affiliation: Department of Neurology and INSPE - Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.|University Vita-Salute San Raffaele Milan, Italy.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Comi
authors.affiliation: Department of Neurology and INSPE - Institute of Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy.|University Vita-Salute San Raffaele Milan, Italy.
authors.forename: Letizia
authors.initials: L
authors.lastname: Leocani
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000000981:diagnostic imaging*; D001369:Axons; D060825:Cognitive Dysfunction / Q000000981:diagnostic imaging*; D005260:Female; D057180:Frontotemporal Dementia / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D000073216:Mental Status and Dementia Tests; D009929:Organ Size; D012160:Retina / Q000000981:diagnostic imaging*; D012720:Severity of Illness Index; D041623:Tomography, Optical Coherence
keywords: Alzheimer’s disease; frontotemporal dementia; ganglion cell layer; optical coherence tomography; retinal nerve fiber layer