BDNF and dementia: Specifically, the patients with severe dementia had significantly lower plasma BDNF concentration than persons with mild-to-moderate dementia (p = 0.013; post hoc Dunn test) and MCI (p < 0.001; post hoc Dunn test), while patients with mild-to-moderate dementia had lower BDNF concentration than individuals with MCI (p = 0.006; post hoc Dunn test).