Residents of small assisted living communities are more likely to be younger than 65 and have a developmental disability or mental illness than those in a large community, according to newly published research.

Researchers at George Mason University analyzed data on 2,300 AL facilities contained in a 2010 survey done by the Centers for Disease Control and Prevention. The research team broke down the AL communities by size, defining a small community as having between 4 and 10 beds, and a large community as at least 26 beds.

About a fifth of residents in small communities were younger than 65, compared to about 7% in larger communities. About 13% of residents in small communities had a severe mental illness, which was about double the proportion in large communities. There were five times as many residents with developmental disabilities in small communities.

“It’s important to recognize we are not drawing conclusions about the quality of care between communities of different sizes,” stated Andrew Carle, executive-in-residence and director of George Mason’s Program in Senior Housing Administration.

Regulators and consumers both tend to “lump all ALs together,” so this study is doing a service by shedding a light on the particular resident populations served by ALs of different sizes, Carle noted in an email to McKnight’s.

Among the most unexpected findings: Small AL facilities are more likely than large facilities to be serving residents with Alzheimer’s disease, at 53% to 41%. The study authors describe this as a “unique twist,” since Alzheimer’s is associated with age and larger ALs have an older population, on average.

The research was supported by the Assisted Living Federation of America.