Brain health as opposed to mental health is a neglected phenomenon, less discovered now capturing more attention. Currently, the concepts surrounding brain health are vague and no clear definition of this term exists. Assessing brain’s health early in life may offer insights into impending disruptions brain function. If deteriorating or poor health of the brain is detected at a young age, therapeutic steps can be taken. The definition of brain health - “the preservation of optimal brain integrity and mental and cognitive function at a given age in the absence of overt brain diseases that affect normal brain function”. Recently cognitive age has been used as a better indicator of brain health called it the “Cognitive clock”. This book reviews such as fMRI, EEG and PET scan as well as measuring certain blood and CSF biomarker levels. A new noninvasive, cost effective and easily implemented tool for gauging brain health is introduced. This tool can be used in rural communities as well as in LMIC. This book will focus on development of this new tool for brain health measurement, as well as its cross validation in diseased and healthy population.