Heterogeneous cortical atrophy patterns in MCI not captured by conventional diagnostic criteria

Area of Science:

• Neuroimaging
• Neurology
• Cognitive Science

Background:

• Mild cognitive impairment (MCI) is a transitional stage between normal aging and dementia.
• Existing diagnostic criteria for MCI may not fully capture the heterogeneity of the condition.
• Empirically derived MCI subtypes have been identified, but their neurobiological underpinnings require further investigation.

Purpose of the Study:

• To investigate regional cortical thickness differences among empirically derived mild cognitive impairment (MCI) subtypes.
• To determine if distinct MCI subtypes exhibit unique patterns of cortical atrophy.
• To assess the validity of current MCI diagnostic criteria and explore potential improvements.

Main Methods:

• Analysis of cortical thickness in 32 regions per hemisphere from 485 individuals with MCI and 178 cognitively normal controls.
• Utilized data from the Alzheimer's Disease Neuroimaging Initiative (ADNI).
• Employed statistical group maps to compare cortical thickness between MCI subtypes and cognitively normal participants.

Main Results:

• Each MCI subtype displayed a pattern of cortical thinning that aligned with its specific cognitive profile.
• No significant cortical thickness differences were observed between the cluster-derived normal MCI subtype and cognitively normal individuals.
• Direct comparisons between MCI subtypes indicated that cortical thinning patterns reflect increasing severity of cognitive dysfunction.

Conclusions:

• An ordered pattern of cortical atrophy exists in MCI patients, correlating with progressive cognitive dysfunction.
• Conventional diagnostic criteria for MCI may overlook important heterogeneity and are susceptible to false-positive errors.
• Refining MCI diagnostic criteria and subgrouping patients based on cognitive and biomarker profiles are crucial for accurate staging and prognosis.