Cerebral perfusion as a modulator of structural-functional coupling and depressive symptoms: a blue-green light intervention study on subjective memory complaints in women

Aim Subjective memory complaint (SMC) is a preclinical Alzheimer’s manifestation, defined as self-reported memory impairment without objective signs in older individuals, particularly women. Blue-green light therapy has been shown to improve cognitive decline and affective deterioration. However, it remains unclear whether blue-green light affects the perfusional and structural-functional coupling of light-sensitive neural pathways in individuals with SMC.Methods In this study, 13 females with SMC underwent a blue-green light intervention. Changes in cerebral blood flow (CBF), structural-functional connectivity bandwidth, and depressive symptom scores were calculated, followed by a moderating analysis.Results We found that the alteration of CBF after light intervention showed a significant moderation effect on the relationship between the structural-functional coupling characteristics and depressive symptoms. In the right ventral tegmental area (VTA)-right lobule III of cerebellar hemisphere (CER3) edge (ΔCBF in VTA: ΔF = 13.625, p = 0.008; ΔCBF in CER3: ΔF = 23.584, p = 0.002), the intralaminar of thalamus (tIL)-VTA edge (ΔCBF in tIL: ΔF = 22.768, p = 0.002) and the left pulvinar lateral of thalamus (tPuL)-VTA edge (ΔCBF in tIL: ΔF = 11.835, p = 0.011), significant moderation effects of ΔCBF were found.Conclusion Our findings suggested that alterations of CBF might be critical modulating factors, interacting with the structural-functional coupling characteristics of light-sensitive pathways and ultimately regulating depressive symptoms. The current study may provide new insight regarding the physiological mechanisms underlying light-regulated depressive symptoms in older women with SMC.