There are 12 patients who are fit to be discharged taking up beds each day at the West London Mental Health Trust, figures show.
With elderly patients often stuck waiting to be signed off, there is concern over the impact delays can have on their health.
According to the NHS, a hospital stay of more than 10 days for a person over 80 can lead to 10 years of muscle ageing.
NHS England figures show that in February, patients at the West London Mental Health NHS Trust spent a total of 338 days waiting to be discharged or transferred to a different care facility.
That’s equivalent to nearly a year of waiting time.
The figures show that 38% of the delays were caused by problems within the NHS, like waiting for a bed to open up in a rehabilitation centre or mental health hospital.
A further 36% were caused by problems with social care, such as delays in setting up community care or special equipment at home.