The rMT, however, is highly dependent on the coil-cortex distance when expressed as the percentage of the maximal cortical stimulator output. Therefore, instead of using the rMT to assess the motor cortex excitability, the corresponding value of the electrical field, EFMT, induced on the cortex by the magnetic stimulation should be used. Unfortunately, the true induced electric field is not measurable noninvasively. However, the induced electric field can be estimated based on the stimulation intensity, coil orientation and characteristics, and shape of the subject’s head. Furthermore, the individual coil-cortex distance can be taken into account in the estimation of EFMT by utilizing the subject’s individual MRIs. Thus, by using EFMT, the assessment of cortical excitability can be based on purely neuronal basis irrespective of the distance between the stimulation coil and cortex. Previously, cortical thickness analysis on AD patients has revealed cortical thinning in several brain areas known to be affected by AD neuropathology and this thinning has been shown to be related to the clinical severity of AD, even in the early stage of the disease. Furthermore, cortical thickness analysis has been proposed to have diagnostic utility in differentiating various neurodegenerative diseases and their variants, and perhaps also in predicting the progression from MCI to AD i.e. due to the NVP-BKM120 different thickness profiles. Other widely used techniques to study brain atrophy in vivo are the different MRI volumetric methods, with voxel-based morphometry being one of the most widely used techniques. VBM, however, does not provide information about brain atrophy at the single-subject level i.e. it permits only group-level analysis. Cortical thickness analysis provides grey matter thickness information both in the subject’s native space and in standard stereotactic space. This feature makes cortical thickness analysis suitable for both general group-level analysis and also for individual diagnostic purposes. There are very few studies combining functional information of cortical excitability with structural information of brain. Using diffusion tensor imaging rMT has been correlated with the fractional anisotropy of the white matter underlying the primary motor and premotor areas. Furthermore, by combining VBM results with rMT, it was found that the age-related volumetric findings such as increased cerebrospinal fluid volume could be associated with lower rMT. Relative changes in grey matter density have been correlated with the changes in cortical excitability in subjects suffering from writer’s cramp. However, no direct comparison of the cortical grey matter thickness and the cortical excitability has ever been performed. Previously, it has been suggested that neuronal loss might be one of the reasons responsible for motor cortex hyperexcitability in AD patients. The aim of this study was to examine this hypothesis by combining the cortical thickness analysis revealing the neuronal loss with the cortical excitability based on the EFMT.