Prof Tara Spires-Jones, president of the British Neuroscience Association, said the EMA’s decision will come as “a disappointment to many”.
But she said there were reasons to remain hopeful.
“Lecanemab has shown that it is possible to slow down disease progression, and research does work. Now we need to ramp up our efforts to discover new and safer treatments,” Prof Spires-Jones said.
Prof John Hardy, professor of neuroscience and group leader at the UK Institute for Dementia Research, University College London (UCL), said the decision could have unintended consequences.
“I am sure we will now see rich people with early Alzheimer’s disease flying to the US or other jurisdictions for treatment.”