Neurochemical imaging offers an opportunity to study at a molecular level in-vivo the neuronal substrates that underpin Alzheimer's disease (AD) and related disorders, such as mild cognitive impairment (MCI). Proton magnetic resonance spectroscopic imaging (1H MRSI) measures have the potential of offering a relatively direct window into neurochemical alterations in the brain. This chapter reviews key findings of 1H MRSI in AD, MCI and aging, and discusses the potential value of this technology for diagnosis and prognosis of AD as well as for the assessment of therapeutic intervention. Other promising neurochemical imaging modalities that directly probe neurotransmitter systems using radioactive positron emission tomography (PET) tracers and amyloid PET imaging are also discussed. Overall, MRS is a promising investigational technique in dementia and related cognitive disorders to provide unique measures of multivariate spectroscopic profiles of the brain.