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Targeted brain stimulation improves age-related memory

High-frequency transcranial magnetic stimulation, or TMS, targeting the hippocampus can engage behavioral and neural characteristics of age-related memory impairment in older adults, according to a pilot study published in Neurology.

Joel L. Voss, PhD, associate professor at Northwestern University Feinberg School of Medicine, and colleagues examined whether targeting hippocampal-cortical brain networks with high-frequency TMS could improve age-related memory impairment in 15 older adults aged 64 to 80 years.

Participants completed a single-blind, sham-controlled experiment where TMS was applied to participant-specific lateral parietal locations based on their functional MRI connectivity with the hippocampus. The researchers acquired functional MRI while participants learned objects paired with scenes and with locations, then examined recognition of objects and recollection of object associations before, 1 day after and 1 week after participants received stimulation or low-intensity sham.

After receiving stimulation, older adults’ recollection impairment no longer differed significantly from younger adults in the control sample (t₃₀ = 0.78; P = .44), the results showed.

“Older people's memory got better up to the level that we could no longer tell them apart from younger people. They got substantially better,” Voss said in a press release.

Voss and colleagues found that TMS improved older adults’ recollection more than recognition at the 24-hour assessment compared with sham (t₁₄ = 2.77; P = .02), with a robust improvement in recollection (t₁₄ = 3.25; P < .01) and weak improvement in recognition (t₁₄ = 2.25; P = .04). On average, older adults saw a 31.1% improvement in recollection after stimulation from baseline (t₁₄ = 3.1; P < .01) and a 2.8% improvement in recognition (t₁₄ = 1.55; P = .14).

Although recollection remained significantly elevated at 1-week follow-up testing compared with baseline, there was no significant differentiation from sham, according to the results.

TMS increased recollection more than recognition in the targeted network as compared to the control network (t₁₄ = 2.1; P = .05). When compared with sham, older adults had significant and consistent increases in recollection activity for the targeted network (t₁₄ = 2.38; P = .03) but not for the control network (t₁₄ = 0.55; P = .59). In addition, the researchers found that stimulation increased functional MRI activity at the hippocampal target for recollection (t₁₄ = 2.9; P = .01) but not for recognition (t₁₄ = 0.43; P = .68) in older adults.

“Network-targeted noninvasive stimulation can selectively engage behavioral and neural characteristics of age-related memory impairment,” Voss and colleagues wrote in the full study. “These findings motivate future studies to optimize the effectiveness of noninvasive stimulation for treatment of age-related memory impairment and to improve mechanistic understanding of the hippocampal-cortical networks that support episodic memory across the lifespan.” – by Savannah Demko

Disclosure: The authors report no relevant financial disclosures.