Optical Neuroimaging and Cognition

Summary

Dementia is associated with a variety of neurovascular and neurometabolic abnormalities. Traditional imaging techniques used to investigate such abnormalities, such as Positron Emission Tomography and functional Magnetic Resonance Imaging, are not always well tolerated, have expensive start up and running costs, and are limited with regards to the types of experiments that can be performed as they can be highly sensitive to movement, are noisy, and have physical restrictions. Near-infrared spectroscopy (NIRS) is a non-invasive neuroimaging technique which uses light in the near-infrared spectrum to detect relative changes in concentration of oxygenated and deoxygenated haemoglobin, and the oxidation state of Cytochrome C Oxidase. As such, NIRS can provide measures of brain oxygenation and metabolism. NIRS is less sensitive to movement, is well tolerated and has few contraindications. It is thus a promising candidate for use in clinics or in peoples' homes for monitoring dementia. In the present study, the investigators aim to use both dual-wavelength and broadband NIRS in a range of dementia subtypes, including Alzheimer's Disease and Dementia with Lewy Bodies, and severities, including Mild Cognitive Impairment, to identify how brain oxygenation and metabolism is altered in dementia and across various clinical subgroups. The investigators also aim to determine the relationship between brain oxygenation and metabolism in dementia, and use machine learning approaches to identify optical biomarkers for dementia.

Eligibility

Inclusion Criteria:

1. A diagnosis of probable:

   * Lewy Body Dementia
   * Alzheimer's Disease
   * Mild Cognitive Impairment (MCI-LB or MCI-AD) OR
2. Cognitively normal for their education and age, with a MMSE score above 26 AND

   * A good grasp of the English language
   * An informant (either a carer or family member) who will be available throughout testing (only relevant if in a patient group)

Exclusion Criteria:

1. Severe dementia

   * Unable to participate
   * A MMSE score below 12
2. A condition which influences metabolism or haemodynamics

   * Such as metabolic or respiratory disorders
3. A significant mental illness

   * Such as rheumatoid arthritis, systemic lupus erythematosus
   * Oral steroid use
4. A significant psychiatric disorder
5. MCI due to other causes such as traumatic brain injury, vascular dementia, or fronto-temporal dementia
6. A history of excessive drug or alcohol use
7. Contraindications to MRI (only for patient groups undertaking the MRI scan: AD/MCI/DLB)

   * Surgical implants e.g. pacemakers
   * Obesity

Conditions4

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