Sentence:  Many hospitals have not taken simple steps to <WSD>lessen</WSD> the distress and confusion which dementia sufferers' often feel on being somewhere so unfamiliar – such as making signs large and easy to read, using colour schemes to help patients find their way around unfamiliar wards and not putting family mementoes such as photographs nearby. 
Meaning of the word marked with <WSD> tags:  To make less; to diminish; to reduce.