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A global initiative is presently underway to develop methods to halt the progression of mild cognitive impairment to dementia.
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The COMCID Study Raises New Questions in Dementia Research

The COMCID study is Japan’s first multicenter investigator-initiated clinical trial involving patients with mild cognitive impairment

National Cerebral and Cardiovascular Center
Published:Dec 04, 2023
|2 min read
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The Cilostazol for prevention of COnversion from MCI to Dementia (COMCID) study demonstrated the safety of cilostazol, an antiplatelet drug, in patients with mild cognitive impairment (MCI) but did not demonstrate any efficacy in preventing disease progression. However, after administration of cilostazol, the blood concentrations of the albumin and β-amyloid complex (albumin-Aβ complex) increased in the treated patients compared with those receiving placebo.

This finding indicates that cilostazol may promote the clearance of β-amyloid—a waste product that accumulates in the brains of patients with dementia—into the blood. Previous studies demonstrated the effect of cilostazol metabolites in improving cognitive function. The researchers plan to identify a group in which cilostazol is effective (cilostazol-responders), to enable investigation of its anti-dementia effects.

Dementia in Japan and around the world

Currently, more than five million dementia patients are in Japan, and the MCI patient total is soon estimated to reach a similar number. A global initiative is presently underway to develop methods to halt the progression of this disease. Previously, a group led by Masafumi Ihara, MD, PhD, FACP, director of the National Cerebral and Cardiovascular Center (NCVC) Department of Neurology, discovered through animal experiments that cilostazol promoted the elimination of β-amyloid plaques in many patients with dementia. However, whether cilostazol is effective in preventing dementia in humans remains unclear, emphasizing the need for verification.

In May 2015, a research group led by Ihara began a nationwide, multicenter, investigator-initiated, double-blinded, and randomized trial—the COMCID study—where patients with MCI received either cilostazol or a placebo for 96 weeks.

Results of the COMCID study

This study demonstrated that cilostazol was safe when administered to patients with MCI. However, it did not prevent progression of MCI to dementia. Nevertheless, the blood concentrations of the albumin and β-amyloid complex (albumin-Aβ complex) in patients receiving cilostazol increased following treatment compared with those receiving placebo. This suggests that cilostazol may have promoted the clearance of β-amyloid from the brain into the blood, consistent with the results of past animal experiments.

The road ahead

Though this study did not demonstrate that cilostazol was safe and suitable for all patients with MCI, it established a crucial, clinical trial-ready cohort for future research investigating cognitive dysfunction. The COMCID study enables further exploration of the efficacy and safety of anti-dementia drug candidates developed worldwide.

- This press release was originally published on the National Cerebral and Cardiovascular Center website