More recently, a research about cognitive profiles in SPG4-related pure HSP has found that subtle cognitive deficits not compatible with dementia were detected by discrepancy between normal MMSE and decreased MoCA scores in adult patients, and there was similar cognitive performances between truncating (nonsense and frameshift mutations) and non-truncating (missense and in-frame insertion) variants, which is consistent with SPG11-related HSP-TCC patients reported in our study [25]. This evidence concerns the gene SPG11 and dementia.