(Elsevier, 1993) Williams, Robert J.; Schmidt, Glen G.
The frequency of seasonal affective disorder (SAD) was examined in clients receiving treatment for recurrent mood disturbances in a northern Canadian site. Approximately one-fifth of these individuals were identified as having SAD using file histories and a statistical criterion as the basis for assessment. The failure to find a higher prevalence rate at this latitude may be due to other studies' reliance on client self-report, a tendency for individuals with SAD to relocate south, or a greater tendency for SAD to be seen by general practitioners and alcohol treatment centres in the north.