Alzheimer hastalığında transkraniyal manyetik stimülasyonun hipokampal alt alanlar üzerindeki yapısal etkileri

Year 2025, Volume: 30 Issue: 1, 62 - 70, 29.01.2025

Halil Aziz Velioglu , Betül Sümbül Şekerci , Taha Hanoğlu , Ali Behram Salar

https://doi.org/10.21673/anadoluklin.1595288

Abstract

Amaç: Bu çalışma, Alzheimer hastalığı (AH) olan bireylerde tekrarlayan transkraniyal manyetik stimülasyonun (rTMS) hipokampal alt alanlar ve kortikal şekil metrikleri üzerindeki yapısal etkilerini araştırmaktadır. Yüksek çözünürlüklü MRI segmentasyonu ve Hippunfold analizi kullanılarak, TMS kaynaklı yapısal değişiklikleri incelemeyi ve TMS’nin olası nöroprotektif rolünü değerlendirmeyi amaçlıyoruz.

Yöntemler: Bu retrospektif çalışmada, 17 AH hastası ve 18 sağlıklı kontrol (SK) yer aldı. AH hastalarına, iki hafta boyunca toplam 10 seanslık sol lateral paryetal korteksi hedefleyen 20 Hz rTMS uygulandı. Tedavi öncesi ve sonrası MRI görüntüleri Hippunfold yazılımıyla analiz edilerek hipokampal alt alanlar segmentlendi ve kortikal kalınlık ile şekil metrikleri çıkarıldı. Gruplar arası ve zaman noktaları arasındaki karşılaştırmalar için istatistiksel analizler yapıldı.

Bulgular: Hipokampal volumetrik analiz, AH hastalarında Cornu Ammonis 1, (CA1), CA2, CA4, dentat girus (DG), subikulum ve stratum radiatum-lacunosum-moleculare (SRLM) gibi alt alanlarda belirgin atrofi olduğunu ortaya koydu. TMS sonrası anlamlı bir volumetrik iyileşme gözlenmese de, sağ CA3 alt alanında progresif atrofi tespit edildi (p=0.005). Kortikal şekil analizleri, AH hastalarında hipokampal kalınlıkta (p<0.001) ve yüzey alanında (p<0.001) sağlıklı kontrollere kıyasla anlamlı azalmalar olduğunu gösterdi ve her iki hemisferde de TMS öncesi ve sonrası arasında kortikal incelme görüldü. Bu bulgular, TMS tedavisine rağmen devam eden nörodejenerasyonu işaret etmektedir.

Sonuç: TMS, bu çalışmada hipokampal atrofiyi veya kortikal incelmeyi anlamlı şekilde tersine çevirmemiştir. Ancak, sol hipokampal alt alanların sağa göre daha stabil olması, TMS’nin potansiyel nöroprotektif etkilerini işaret etmektedir. Bu sonuçlar, TMS’nin AH progresyonunu hafifletme potansiyelini araştırmak için daha uzun süreli ve çift taraflı stimülasyon protokollerinin gerekliliğine dikkat çekmektedir.

Keywords

Alzheimer hastalığı, atrofi, hipokampus, transkraniyal manyetik uyarı

The structural effects of transcranial magnetic stimulation on hippocampal subfields in Alzheimer's disease

Abstract

Aim: This study investigates the structural effects of repetitive transcranial magnetic stimulation (rTMS) on hippocampal subfields and cortical shape metrics in Alzheimer’s disease (AD) patients. Using high-resolution MRI segmentation and analysis via Hippunfold, we aim to elucidate TMS-induced structural changes and assess its potential neuroprotective role.

Methods: This retrospective study included 17 AD patients and 18 healthy controls (HC). AD patients underwent 20 Hz rTMS targeting the left lateral parietal cortex over 10 sessions across two weeks. Magnetic resonance imaging (MRI) data were acquired before and after rTMS and analyzed with Hippunfold to segment hippocampal subfields and extract cortical thickness and shape metrics. Statistical analyses were performed to compare subfield volumes and cortical metrics between groups and across time points.

Results: Hippocampal volumetric analysis revealed significant atrophy in subfields such as Cornu Ammonis 1, (CA1), CA2, CA4, dentate gyrus (DG), subiculum, and stratum radiatum-lacunosum-moleculare (SRLM) in AD patients compared to HC. Although no significant volumetric recovery was observed post-TMS, a further decline was noted in the right CA3 subfield (p=0.005), highlighting progressive atrophy. Cortical shape analyses showed significant reductions in hippocampal thickness (p<0.001) and surface area (p<0.001) in AD patients versus HC, with further cortical thinning in both hemispheres between pre- and post-TMS conditions. These findings suggest ongoing neurodegeneration despite TMS treatment.

Conclusion: TMS did not significantly reverse hippocampal atrophy or cortical thinning in this cohort. However, observed asymmetry in atrophy patterns, with relatively stable left hippocampal subfields compared to the right, suggests potential neuroprotective effects of TMS. These results highlight the need for prolonged and bilateral stimulation protocols to explore the therapeutic potential of TMS in mitigating AD progression.

Keywords

Alzheimer’s disease, atrophy, hippokampus, transcranial magnetic stimulation

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