The intervention program proof-of-concept was assessed as a single-arm, within-subjects clinical study with a target enrollment of 10 participants with possible or probable amnestic MCI. The protocol required participants to complete a pre-intervention assessment within two weeks of beginning the intervention, attend seven, one-hour intervention group sessions across six weeks, complete a post-assessment and interview in the final week of the intervention, and complete weekly surveys throughout the intervention.

The primary goal of the proof-of-concept phase is to use pre-post comparisons to determine if the treatment package can produce clinically significant improvements. Thus, our goal was to assess whether the MI-CBT KNA program influenced adherence to KN and cognitive outcomes. Of note, recruitment for the trial occurred in the weeks leading up to the COVID-19 pandemic, which substantially altered the original intervention and assessment design due to restrictions on in-person human subject research. While the original protocol included in-person assessments and group meetings, collection of multiple biological samples (i.e., lipid panels, basic vitals, inflammatory biomarkers), and weekly health assessments, these in-person components were modified or removed for completion during the COVID-19 pandemic. Pre-assessment and screening appointments described below were completed in-person prior to the COVID-19 pandemic. Thus, we completed pre-intervention neuropsychological assessments with participants at baseline prior to beginning the trial; however, immediately following baseline assessments, we fully revised the protocol to include only online, video, and phone contact. We moved the KNA program to an online platform (HIPAA-compliant Zoom), and assessments were changed to online surveys and video assessments. Individual testing of the video platform was completed prior to the trial, which successfully reduced technical problems.

The MI-CBT KNA Program proof-of-concept was assessed as a single-arm, within-subjects clinical study with a target enrollment of 10 participants with possible or probable amnestic MCI. The protocol required participants to complete a pre-intervention assessment within two weeks of beginning the intervention, attend seven, one-hour intervention group sessions across six weeks, complete a post-assessment and interview in the final week of the intervention, and complete weekly surveys throughout the intervention. Participants were mailed materials, including the participant workbook and food, macronutrient, and ketone logs. Participants were also sent two bottles of ketone urine test strips for daily testing and materials to complete follow-up assessments. Throughout the program, participants were instructed to titrate into full ketosis across the first four weeks of the program by gradually reducing total carbohydrate intake and increasing healthy fat intake (e.g., fish, nuts, avocado, olive oils etc.). Thus, participants were not expected to attain measurable ketone levels until the final weeks of the program.

Inclusion Criteria:

• Final inclusion criteria included individuals who met criteria for "possible" Mild cognitive impairment (MCI), which was defined as the following: evidence of either subjective decline in memory and greater self-reported use of compensatory strategies OR poorer performance than expected in one or more cognitive domain OR limited evidence of impairment in both subjective and objective findings.

Exclusion Criteria:

• Presence of severe and/or unstable medical conditions
• diagnosable major neurocognitive disorder

Baseline to 3 months post-intervention (approximately 6 months)