In this manuscript , we study properties of long-term optical variability of a large sample of 106 SDSS spectroscopically confirmed AGN with double-peaked broad low-ionization emission lines ( double-peaked emitters ) .
The long-term optical light curves over 8 years are collected from the Catalina Sky Surveys Data Release 2 .
And , the Damped Random Walk ( DRW ) process is applied to describe the long-term variability of the double-peaked emitters .
Meanwhile , the same DRW process is applied to long-term optical light curves of more than 7000 spectroscopically confirmed normal quasars in the SDSS Stripe82 Database .
Then , we can find that the DRW process determined rest-frame intrinsic variability timescales \ln ( \tau / { days } ) are about 5.8 and about 4.8 for the double-peaked emitters and for the normal quasars , respectively .
The statistically longer intrinsic variability timescales can be confirmed in the double-peaked emitters , after considerations of necessary effects , such as the effects from different distributions of redshift , BH mass and accretion rate between the double-peaked emitters and the normal quasars .
Moreover , a radial dependence of accretion rate \dot { m } _ { R } ~ { } \propto~ { } R ^ { \beta } with larger values of \beta could be an acceptable interpretation of the longer intrinsic variability timescales in the double-peaked emitters .
Therefore , there are different intrinsic properties of emission regions between the double-peaked emitters and the normal quasars .
The double-peaked emitters can be well treated as an unique subclass of AGN .