Cortical excitability and age-related volumetric MRI changes

Area of Science:

• Neuroscience
• Gerontology
• Medical Imaging

Background:

• Normative transcranial magnetic stimulation (TMS) data for cortical excitability in the elderly is limited.
• Elderly individuals are often used as controls in TMS studies for neurological conditions.
• The significance of age-associated increases in ventricular cerebrospinal fluid (vCSF) and white matter hyperintensities (WMH) in non-demented elderly is unclear.

Purpose of the Study:

• To investigate the relationship between age-associated MRI changes (vCSF, WMH, CNS volumes) and cortical excitability measures in healthy elderly subjects.
• To provide normative data on TMS-derived cortical excitability in the elderly.
• To inform the interpretation of TMS studies involving elderly control groups.

Main Methods:

• Twenty-four healthy elderly participants underwent TMS testing.
• Measurements included resting motor threshold (RMT), cortical silent period (cSP), and central motor conduction time.
• MRI was used to quantify vCSF, WMH, and central nervous system (CNS) volumes.

Main Results:

• Increased vCSF and WMH volumes correlated with decreased RMT in both hemispheres.
• Smaller CNS volumes were associated with decreased RMT and shorter cSP in the right hemisphere.
• These findings suggest a link between common age-related MRI alterations and heightened cortical excitability.

Conclusions:

• Age-associated MRI findings, such as increased vCSF and WMH, are associated with increased cortical excitability.
• These neuroimaging changes may reflect cellular alterations impacting cognitive and motor function in the elderly.
• Future TMS studies should consider neuroimaging markers of neurodegeneration in elderly controls.