DJ_Keyser’s review published on Letterboxd:
Altered States would make an interesting double bill with 2001: A Space Odyssey; where Kubrick’s classic saw consciousness expanded under the influence of a black monolith, Ken Russell’s exploration into the recesses of the human mind sees drug-induced cognitive intumescence become a catalyst for inexplicable and phenomenal regression into a primitive state. It suggests that no matter how deep or far humanity’s reach extends, we forever remain tied to our base urges, dormant as they may seem. Altered States does fumble the ending, unfortunately, but it matters little. The 95 minutes beforehand provide a potent dose of brain-bleeding sci-faux horror with striking hallucinogenic imagery that will sear the cerebral cortex like the baddest of trips.