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Microplastics and Parkinson’s Disease: 6 Plausible Brain-Risk Pathways

MHD featured image for microplastics and neurodegenerative disease mechanisms.

A 2026 mechanistic review linked microplastics to 6 proposed Alzheimer’s disease pathways and 6 proposed Parkinson’s disease pathways.1 The calibrated interpretation is that microplastics are biologically plausible brain stressors, but the human evidence does not yet prove that they cause Parkinson’s disease or Alzheimer’s disease. Research Highlights Exposure is widespread: the review cited an estimate …

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Entorhinal Dopamine Fails Early in Alzheimer’s Mice

Editorial card showing the lateral entorhinal cortex with dopamine projections from the midbrain, illustrating an early-Alzheimer's mechanism finding rescued by L-DOPA in mice.

A 2026 Nature Neuroscience study from the Igarashi lab proposes a circuit-level answer for why the lateral entorhinal cortex (LEC) is the first cortical region to falter in Alzheimer’s: dopamine inputs from the VTA and substantia nigra to the LEC go functionally silent at the earliest disease stage in an APP knock-in mouse — before …

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Falling Dementia Rates Linked to Generational Memory Gains

Photoreal illustration representing generational gains in memory across older adults, with imagery of overlapping age trajectories and hippocampal motifs.

Dementia rates in the US, UK, Netherlands, Sweden, France, and several other high-income countries have been falling for decades, despite population aging. The standard explanation — improved cardiovascular care, more education, and less smoking in later-born cohorts — is real but incomplete. Research Highlights Dementia incidence has been falling about 13% per decade in Western …

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tDCS Plus Cognitive Training Improved Cognition Short-Term by SMD 0.36

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A 2026 medRxiv meta-analysis of 27 trials found that transcranial direct current stimulation added to cognitive training improved global cognition immediately after treatment by SMD 0.36 compared with cognitive training alone.1 The signal was small, short-term, and rated very low certainty, so it is not evidence that tDCS is a durable cognitive-rehabilitation shortcut. Research Highlights …

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Epilepsy and Alzheimer’s Blood Biomarkers in Older Adults

MHD featured image for epilepsy, Alzheimer’s blood biomarkers, and AT(N) profiles in older adults.

A preprint in 84 older adults with epilepsy found that abnormal Alzheimer's-related blood biomarkers were common, but the biomarker categories did not line up neatly with cognitive impairment. Research Highlights Only 32.1% had normal biomarkers: 27 of 84 older adults with epilepsy were A−T−N− using blood-based amyloid, tau, and neurodegeneration markers.1 AD-continuum profiles were common: …

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Alzheimer’s Neurovascular Unit Dysfunction May Start Before Amyloid

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A 2026 review argues that neurovascular-unit dysfunction may precede amyloid-beta generation in Alzheimer’s disease and then synergize with amyloid deposition, tau pathology, inflammation, and neuronal loss.1 The model is vascular biology plus amyloid biology: blood vessels, barrier integrity, and amyloid deposition can amplify each other early enough to affect dementia risk and progression. Research Highlights …

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Thymol Carbamate TC-6 Improved Memory in Alzheimer’s Mice by Blocking BuChE

MHD featured image for thymol carbamate TC-6, BuChE inhibition, and Alzheimer's mouse-model memory testing.

A 2026 medicinal-chemistry study found that thymol carbamate TC-6 inhibited human butyrylcholinesterase at 3.6 nM, showed more than 2,500-fold selectivity over human acetylcholinesterase, crossed a blood-brain-barrier screening assay, and improved spatial-memory behavior in amyloid-β-injected mice. Research Highlights TC-6 hit BuChE hard: Wu et al. reported human butyrylcholinesterase (BuChE) inhibition at 3.6 nM, compared with 9,320 …

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