ADL and IADL scales
/ A-D-L; I-A-D-L /
Living independently is really two layers of tasks. The first layer is taking care of your own body — eating, washing, dressing, using the toilet, moving around. The second is running a household and a life — cooking, shopping, handling money, taking medicines, using the phone, getting around the community. Rehabilitation gives these two layers names: the basic activities of daily living, or ADLs, and the instrumental activities of daily living, or IADLs. ADL and IADL scales are the structured checklists that score how independently a person manages each.
ADL scales (the Barthel Index and the Katz index are classic examples) cover the basic, near-universal self-care tasks; their items are similar across people and cultures because nearly everyone eats and dresses. IADL scales (such as the Lawton scale) cover the more complex tasks that require planning, judgment, and interaction with the world — preparing meals, managing finances, organizing transport. These higher tasks lean heavily on thinking and memory, so they often slip before basic self-care does. That ordering is itself useful: someone who can still bathe and dress but can no longer manage their medications or pay bills may be in the early stages of a thinking problem, even though their body works fine.
These scales matter because they map the realistic question of whether a person can be safely left alone, and at what level of support. The ADL/IADL distinction guides discharge planning — going home alone, going home with help, or moving to a supported setting — and it makes the assessment honest about a subtle point: IADLs are more shaped by culture, gender roles, and what a person used to do, so a man who never cooked is not 'disabled' for not cooking. The scales describe support needs; they do not judge a life.
An older man scores full marks on a basic ADL scale — he washes, dresses, and feeds himself perfectly. But on an IADL scale he can no longer manage his pills, pay bills, or cook safely. That split, with the body intact but the higher tasks slipping, is an early clue to a memory problem and changes the support he needs at home.
IADLs lean on thinking, so they often slip before basic self-care does.
IADLs are shaped by culture, gender roles, and personal history, so 'cannot cook' is not automatically a disability — the scale measures support needs against a person's own life, not against a universal standard.