Which plants are neurotoxicants associated with CNS depression?

• A. Cannabis, Isocoma, Stipa
• B. Milkweed, Cicuta
• C. Belladonna, Datura
• D. Ohio buckeye, locoweed

Answer: (A)

The key idea here is recognizing plants that act as neurotoxicants with a tendency to depress the central nervous system. Cannabis can produce CNS depression and sedation, especially at higher doses, with impaired motor coordination and slowed responses. Isocoma (bitterweed) contains compounds such as tremetone/tremetol that can cause a neurologic syndrome in livestock characterized by weakness, ataxia, and general depression—clear CNS depressant effects. Some Stipa grasses have been associated with neurotoxic effects in grazing animals as well, contributing to CNS depression through plant-derived toxins.

The other groups are associated with different neurotoxic patterns. Milkweed primarily presents cardiotoxic effects from cardenolides rather than CNS depression. Cicuta (water hemlock) is renowned for severe CNS stimulation and seizures rather than sedation. Belladonna and Datura cause anticholinergic delirium and agitation, not depression. Ohio buckeye and locoweeds produce neuro signs that are more related to locomotor impairment or chronic neurodegenerative effects rather than acute CNS depression.