As part of the studies, they generated genetic knock-out mice lacking the gene for SAPAP3.
The resulting mice appeared normal until they were between four and six months old, when they started developing lesions on their heads, necks and snouts.
Videotapes of the animals showed they were grooming themselves significantly more than wild-type mice even during times when they would normally be asleep (P<0.05, P<0.01, and P<0.001, depending on the time of day).
In a series of psychological tests, the researchers showed that the knockout mice were also significantly more anxious and timid than their wild-type cousins.
