Table 1 Inclusion and exclusion criteria

Inclusion criteria

1. Diagnosis of aphasia, after stroke, as confirmed by a qualified speech-language therapist ascertained with the Chinese Standard Aphasia Battery (ABC) test [25]

2. Moderate to severe information reduction of verbal production (percentile score of 50 or lower on the ABC verbal production subtest)

3. First onset of stroke, anytime post-stroke

4. Age 20–80 years

5. Mandarin Chinese as the first language

6. Able to participate in intensive therapy

Exclusion criteria

1. Acute stroke with unstable vital signs

2. Premorbid speech and language disorders caused by a neurological deficit other than stroke

3. Premorbid cognitive impairment, mood disorders, and mental disorders affecting communication

4. Severe non-linguistic cognitive disturbances impeding language therapy

5. Presence of serious heart, liver, kidney, infectious disease, and uncontrolled medical problems

6. Concomitant neurological diseases other than stroke