There is little evidence to guide pharmacological treatment in adults with Down syndrome and Alzheimer's disease.

To investigate the effect of cholinesterase inhibitors or memantine on survival and function in adults with Down syndrome and Alzheimer's disease.

This was a naturalistic longitudinal follow-up of a clinical cohort of 310 people with Down syndrome diagnosed with Alzheimer's disease collected from specialist community services in England.

Median survival time (5.59 years, 95% CI 4.67–6.67) for those on medication (n = 145, mainly cholinesterase inhibitors) was significantly greater than for those not prescribed medication (n = 165) (3.45 years, 95% CI 2.91–4.13, log-rank test P<0.001). Sequential assessments demonstrated an early effect in maintaining cognitive function.

Cholinesterase inhibitors appear to offer benefit for people with Down syndrome and Alzheimer's disease that is comparable with sporadic Alzheimer's disease; a trial to test the effect of earlier treatment (prodromal Alzheimer's disease) in Down syndrome may be indicated.

A.S. has undertaken consulting for Ono Pharmaceuticals, outside the submitted work. Z.W. has received a consultancy fee and grant from GE Healthcare, outside the submitted work.

The cost of caring for people with intellectual disability currently makes up a large proportion of healthcare spending in western Europe, and may rise in line with the increasing numbers of people with intellectual disability now living to old age.

To report service use and costs of older people with intellectual disability and explore the influence of sociodemographic and illness-related determinants.

We collected data on receipt and costs of accommodation, health and personal care, physical as well as mental illness, dementia, sensory impairment and disability in a representative sample of adults with intellectual disability aged 60 years and older (n = 212).

The average weekly cost in GBP per older person was £790 (£41 080 per year). Accommodation accounted for 74%. Overall costs were highest for those living in congregate settings. Gender, intellectual disability severity, hearing impairment, physical disorder and mental illness had significant independent relationships with costs. Mental illness was associated with an additional weekly cost of £202.

Older adults with intellectual disability comprise about 0.15–0.25% of the population of England but consume up to 5% of the total personal care budget. Interventions that meet needs and might prove to be cost-effective should be sought.