Brain metabolic correlates of decision making in amnestic mild cognitive impairment

Area of Science:

• Neuroscience
• Gerontology
• Psychiatry

Background:

• Mild cognitive impairment (MCI) is characterized by subtle deficits in medical decision-making capacity (MDC).
• Understanding the neurobiological underpinnings of MDC impairments in MCI is crucial for clinical assessment and care.
• Proton magnetic resonance spectroscopy (MRS) offers a non-invasive method to assess brain metabolite concentrations.

Purpose of the Study:

• To investigate the relationship between posterior cingulate metabolite ratios measured by MRS and medical decision-making capacity (MDC) in individuals with amnestic MCI.
• To identify specific neurochemical markers associated with impaired decisional abilities in MCI.

Main Methods:

• Twenty-nine MCI patients and 42 healthy controls underwent proton magnetic resonance spectroscopy (MRS) of the posterior cingulate.
• MRS assessed ratios of N-acetylaspartate/Creatine (NAA/Cr), Choline/Creatine (Cho/Cr), and myo-Inositol/Creatine (mI/Cr).
• Participants completed the Capacity to Consent to Treatment Instrument (CCTI) to evaluate four decisional standards: choice, appreciation, reasoning, and understanding.

Main Results:

• MCI patients exhibited significantly different MRS ratios (mI/Cr and Cho/Cr) compared to controls.
• MCI patients demonstrated impairments in the understanding and reasoning standards of the CCTI.
• A significant positive correlation was found between the NAA/Cr ratio and performance on the reasoning standard (r = .46, p < .05).

Conclusions:

• Altered brain metabolite profiles, specifically mI/Cr and Cho/Cr, are present in MCI patients.
• MCI is associated with deficits in understanding and reasoning aspects of medical decision-making capacity.
• The correlation between NAA/Cr and reasoning ability suggests that posterior cortical neuronal function is vital for complex decision-making in MCI.