EXHIBIT 23(a)
    
 
   
                   CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
    
 
   
    As independent public accountants, we hereby consent to the incorporation by
reference in this Registration Statement of our report dated November 14, 1997
on the consolidated financial statements and schedule of Magellan Health
Services, Inc. and subsidiaries included in Magellan Health Services, Inc.'s
Annual Report on Form 10-K for the fiscal year ended September 30, 1997, and to
all references to our Firm included in this Registration Statement.
    
 
   
                                          /s/ ARTHUR ANDERSEN LLP
    
 
   
Atlanta, Georgia
October 27, 1998