Language, Speech and Motor Function in MCI Due to AD and Alzheimer's Disease

Inclusion Criteria: A subject with MCI with a likelihood of underlying AD pathophysiology must meet the following criteria: * Established diagnosis of MCI due to AD with a likelihood according to NIA-AA criteria (Albert et al., 2011). * A score of stage three on the Global Deterioration Scale (GDS) (Reisberg et al., 1982). A subject with AD must meet the following criteria: * Established diagnosis of AD (amnestic or non-amnestic) or etiologically mixed presentation of AD according to DSM-5 (American Psychiatric Association, 2013) or NINCDS-ARDRA criteria (Jack et al., 2018; McKann et al., 2011). * The following scores on the Global Deterioration Scale (GDS): four for mild AD, five for moderate AD (Reisberg et al., 1982). All subjects of the control group must meet the following criteria: * A score of stage one or two on the Global Deterioration Scale (GDS) (Reisberg et al., 1982). * They are age-matched with the MCI due to AD or AD patients included in the study. All subjects must meet the following criteria: * First language is Dutch and/or Frisian. * Able to walk independently with or without walking aid. * Able to squeeze with each hand. Exclusion Criteria: A subject with MCI due to AD or AD who meets the following criteria will be excluded from participation in this study: * Having a neurological or neurodegenerative disease or disorder that may be contributing to cognitive impairment above and beyond that caused by AD or mixed AD; Down's syndrome, other subtypes of dementia, autism spectrum disorder. * Having an established diagnosis of a psychiatric disorder, e.g. schizophrenia, depression. All subjects in the control group who meets following criteria will be excluded from participation in this study: ● Suffers from a neurological, neurodegenerative or psychiatric disease or disorder. All subjects in any group who meet any of the following criteria will be excluded from participation in this study: * Hearing loss (with or without hearing aid) that affects communication. * Vision loss (with or without glasses or lenses) that affects communication. * History of language problems, speech problems or dyslexia. * Suffers from additional disorders or diseases which may limit gait, hand grip strength, language and/or speech. * Medication use that influence gait, hand grip strength, speech or language performance at time of testing. * Being terminally ill (i.e., life expectancy \< 2 weeks according to the attending physician).