Greater Manchester Police said the 25-year-old man from Cheetham Hill, Manchester had been assessed by medical staff on Tuesday afternoon after being taken into custody yesterday evening.
The man, who has yet to be identified, stabbed three people including a police officer in Manchester Victoria station on New Year's Eve while screaming 'Allahu Akbar'.
Anti-terror officers raided his home in the city today and spoke to neighbours who said they believe the house was inhabited by a Somali couple.
Neighbours also said the couple have four or five children, who reportedly moved with their parents to the UK from the Netherlands around 12 years ago.
Footage of the aftermath of the 'frenzied' attack at Manchester's Victoria Station last night shows a man being pinned down by five police officers, with blood stains on the pavement.
Another video shows the suspect shouting 'Allahu Akbar', meaning 'God is most great' in Arabic, as he was put in the back of a police van. He was also heard screaming: 'Long live the Caliphate', a reference to the enclave carved out by terror group ISIS.
A witness said he also shouted: 'As long as you keep bombing other countries, this sort of s*** is going to keep happening.'