Dementia is a neurological disease that causes cognitive and behavioral impairments that could ultimately interfere with the ability to function at work or to do the usual daily activities. It is recognized as a healthcare and social burden and remains challenging in terms of proper diagnosis and treatment.

Biomarkers are needed to identify at-risk individuals, stage their disease, and track disease progression. Such biomarkers should be noninvasive, inexpensive, and simple to acquire. Neurodegeneration biomarkers in CSF include neurofilament light (NfL), Chitinase 3-like protein 1 (CHI3L1). NfL for example increases in several neurologic conditions, including AD. In addition, NfL can be detected in serum using standard immunoassay formats. Higher CSF levels of CHI3L1 are seen in patients with neurological disorders such as MS patients experiencing relapses of MS. In addition, C-X-C motif chemokine 13 (CXCL13) is a crucial homeostatic chemokine expressed in lymphoid organs, and it is essential for the recruitment and compartmentalization of lymphocytes. In MS, CXCL13 regulates homing of B cells and subsets of T cells to inflammatory foci in CNS by interacting with the CXCR5 receptor. The levels of CXCL13 are elevated in the CSF of patients with MS compared to healthy controls, as well as in other neuroinflammatory diseases. CXCL13 may be considered a CSF biomarker of intrathecal B cell response, as its levels correlate with the count of B cells, the IgG index, and the presence and OCBs in the CSF.

Transcranial magnetic stimulation (TMS) assesses several cortical properties such as excitability, plasticity, and connectivity in humans. TMS has been applied to patients with dementia, enabling the identification of potential markers of the pathophysiology and predictors of cognitive decline; moreover, applied repetitively, TMS holds promise as a potential therapeutic intervention.

Inclusion Criteria:

1. Men or women of at least 50-80 years of age.
2. Are reliable in individual data and willing to make themselves available for the duration of the study
3. Clear written informed consent obtained from 1st degree of relative from each patient participant and control himself in the trial.

Exclusion Criteria:

1. age below 50 years and above 80 years.
2. other neurological disorders or psychiatric disorders; previous history of stroke; metabolic disturbance; other major medical illnesses; epilepsy; inflammatory, autoimmune, or infectious disease; metallic objects in the body; craniotomy in the past.
3. Presence of clinically significant medical or psychiatric condition that may increase the risk associated with the study
4. Participation in any other type of medical research that may interfere with the interpretation of the study.
5. Patients with severe motor disability (bed-ridden) that may interfere with the study procedure.
6. Patients with history of seizures or epilepsy including history in a first degree relative

case control study, it will include 4 groups of dementia patients in early and late onset, and control healthy group matching with age, sex and educational state.

The study will include 19 patient of each dementia type and 19 controls, each dementia patients were diagnosed according to the international classification of disease 10th revision ICD 10.

Total score of Mini-mental state examination is <24 or 22 in Mini-mental state examination will be used as a screening test for detection of cases.