多くの抗うつ薬によって増加する脳内化学物質のセロトニンが、耳鳴りを増幅させる可能性があるという新たな研究結果が発表された。科学者らは、マウスの脳内でセロトニン濃度の上昇と耳鳴りに似た行動を結びつける特定の神経回路を特定した。
オレゴン健康科学大学と中国の安徽大学の研究チームは、この研究結果を米国科学アカデミー紀要（PNAS）に発表した。研究チームは光遺伝学を用いてセロトニン産生ニューロンを刺激し、聴覚脳領域の活動亢進を確認するとともに、修正を加えた驚愕反応テストを通じてマウスに耳鳴りに似た反応が見られることを観察した。今回の研究は2017年の先行研究を基にしており、SSRI（選択的セロトニン再取り込み阻害薬）の服用によって耳鳴りが悪化したという一部の患者からの報告とも一致している。
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A small controlled experiment reported in Frontiers in Behavioral Neuroscience found that exposure to infrasound—ultra-low-frequency vibration below the range of human hearing—was associated with higher salivary cortisol and more negative mood ratings, even though participants could not reliably detect when the infrasound was present.
Researchers have discovered that psychedelic substances suppress visual processing in the brain, leading to hallucinations by drawing on memory fragments. The study, conducted using advanced imaging on mice, shows how slow brain waves shift perception toward internal recall. These findings could inform therapies for depression and anxiety.
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A randomized clinical trial found that 24 minutes of specially designed music paired with auditory beat stimulation significantly lowers anxiety symptoms. Researchers at Toronto Metropolitan University tested various listening durations on 144 adults with moderate anxiety. The 24-minute session provided the strongest benefits.
Researchers at UCLA Health report that delivering transcranial magnetic stimulation (TMS) in an intensive five-day schedule—five sessions per day for five days—was associated with depression symptom improvements comparable to a conventional six-week schedule in a retrospective analysis of 175 patients with treatment-resistant depression. The study also found that some patients who showed little immediate change after the accelerated course improved noticeably in the following weeks.
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A small clinical trial has found that a single dose of the psychedelic drug dimethyltryptamine (DMT) led to rapid and sustained reductions in depression symptoms when combined with therapy. Participants experienced improvements lasting up to six months, with mild side effects reported. The study highlights potential benefits of short-acting psychedelics for treatment-resistant depression.
A study in Molecular Psychiatry used PET imaging with a new tracer to track changes in AMPA-type glutamate receptors in people with treatment-resistant depression receiving ketamine, reporting that region-specific receptor changes were associated with symptom improvement.