Inclusion Criteria:

for Good aging group:

• Subjects aged 60 years or older
• Frailty Index below the pathological cut-off (>0.25)
• Absence of general cognitive impairment (MMSE > 24 points)
• Absence of a diagnosis of sarcopenia

for Bad aging group:

• Patients aged over 60 years

• Exclusive presence of one of the following diagnoses:

  1. Definite, probable, or probable laboratory-supported Amyotrophic Lateral Sclerosis (ALS), either sporadic or familial, according to the revised El Escorial Criteria for ALS diagnosis.
  2. Parkinson's disease (PD) according to the MDS Clinical Diagnostic Criteria for Parkinson's Disease (Postuma et al., Mov Disord., 2015 Oct; 30(12): 1591-1601).
  3. Alzheimer's disease (AD), possible or probable, according to international diagnostic guidelines.
  4. Diagnosis of severe acquired brain injury according to the Italian Guidelines for the Care of Patients in Vegetative State and Minimally Conscious State 2011 (approved by the Unified Conference on May 5, 2011 - Ministry of Health, Italy), with the presence of Sarcopenia.
  5. Presence of Mild Cognitive Impairment (MCI), subjective memory complaint, or deficit in a single cognitive domain, according to international criteria and in absence of established neurological diseases and sarcopenia.
  6. Presence of Sarcopenia as defined by the EWGSOP2 Sarcopenia Consensus, in the absence of cognitive deficits and established neurological diseases.

Exclusion Criteria:

• Inability to provide informed consent.
• Presence of severe and/or acute comorbidities (e.g., uncontrolled diabetes, heart failure, or a diagnosis of oncological disease), as determined by the research team.
• Evidence of other previous neurological or psychiatric disorders involving the cognitive domain.
• Uncontrolled or complicated systemic diseases or history of traumatic brain injury.
• For subjects with Alzheimer's disease (AD), Parkinson's disease (PD), and Amyotrophic Lateral Sclerosis (ALS), individuals with a history of epilepsy will also be excluded.