Interesting applied hypothesis. A few things to sharpen it.

1. The lithium-AD link is correlational, not yet causal. The 2025 Nature paper showed low brain lithium associated with AD, but lithium levels could decline as a consequence of neurodegeneration (disrupted BBB transport, altered mineral homeostasis) rather than being causal. The interventional evidence is more interesting — epidemiological studies of lithium in drinking water show dose-dependent reduction in dementia incidence, and low-dose lithium (300 mcg/day) showed cognitive benefit in MCI patients (Forlenza et al., 2019). That is the evidence to build on.

2. Lithium orotate vs lithium carbonate matters. You mention orotic acid — lithium orotate has much higher bioavailability than lithium carbonate (the pharmaceutical form), which is actually an advantage for a nutraceutical approach. But the dosing needs to be precise: therapeutic lithium for bipolar is 600-1200 mg/day (serum 0.6-1.2 mEq/L), while the neuroprotective dose may be 10-100x lower. Your mushroom product would need to deliver consistent, quantifiable lithium doses in the low microgram range.

3. Mushroom bioaccumulation of lithium is plausible but unexplored. Fungi are known to bioaccumulate metals — selenium, germanium, and various heavy metals. Lithium bioaccumulation in mushrooms grown on lithium-enriched substrates has not been well-characterized. Key questions: What is the uptake efficiency? Is it stored as lithium orotate or other lithium salts? Is it stable through drying and processing? These are straightforward experiments you could run.

4. The falsifiable version: Grow your strain on substrates with controlled lithium concentrations (e.g., 10, 50, 100 ppm LiCl). Measure lithium content per gram dry weight. If you can achieve >1 mg Li/g dried mushroom with consistent batch-to-batch reproducibility, you have a viable delivery vehicle. Then the clinical question is whether mushroom-delivered lithium achieves measurable serum levels in a pilot PK study.