https://ifs.org.uk/news/cuts-non-health-related-benefits-shift-claimants-disability-benefits
Disability benefits are intended to support people living with disabilities with the additional living costs they face as a result of their condition. They form just one part of the working-age benefit system, and people can claim disability benefits at the same time as other benefits such as universal credit.
Studying four cuts to benefits in the 2010s, including cuts to housing benefit and reductions in the benefit cap, we find consistent evidence that cuts to other (non-health-related) benefits cause rises in disability benefit receipt. This could be because benefit cuts worsen health or because they increase incentives to claim disability benefits.