AMENDMENT TO STOCK PURCHASE AGREEMENT


     This amendment (the "Amendment") to the Stock Purchase Agreement,  dated as
of  August  5,  1997  (the  "Agreement")  between  AETNA  INSURANCE  COMPANY  OF
CONNECTICUT ("Seller") and MAGELLAN HEALTH SERVICES,  INC. ("Purchaser") is made
and entered into as of the 4th day of December, 1997.

     WHEREAS,  Seller and Purchaser  desire to amend the Agreement in the manner
set forth in this Amendment;

     NOW,  THEREFORE,  in  consideration  of the premises and for other good and
valuable   consideration,   the  receipt  and   adequacy  of  which  are  hereby
acknowledged, the parties hereby agree as follows:

     1. Amendment to Section 1.1.

     The  definition  of  "Closing  Stockholder's  Equity" in Section 1.1 of the
Agreement is amended to read, in its entirety, as follows:

          "Closing  Stockholder's  Equity" means the consolidated  stockholder's
     equity of the Company and its consolidated  Subsidiaries as of the close of
     business on the day immediately  preceding the Closing Date as set forth on
     the Closing Balance Sheet less $4,000,000.

     2. Miscellaneous.

     a.  All  references  in the  Agreement  to the  "Agreement"  and any  other
references of similar import shall  henceforth  mean the Agreement as amended by
this  Amendment.  All  capitalized  terms used but not otherwise  defined herein
shall have the  meaning  ascribed  to them in the  Agreement  as amended by this
Amendment.

     b. Except to the extent specifically amended by this Amendment,  all of the
terms and  conditions  contained  in the  Agreement  shall be and remain in full
force and effect.

     c. This Amendment  shall be binding upon and inure to the benefit of Seller
and Purchaser and their respective successors and assigns.

     d. In the event of any inconsistency or conflict between this Amendment and
the Agreement,  the terms,  provisions  and  conditions of this Amendment  shall
govern and control.


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                  IN WITNESS  WHEREOF,  the parties  hereto have  executed  this
Amendment as of the date first written above.

                              MAGELLAN HEALTH SERVICES, INC.


                              By:  /s/ Craig L. McKnight
                                   -----------------------
                                   Name: Craig L. McKnight
                                   Title: Executive Vice President & CFO

                              AETNA INSURANCE COMPANY OF
                                 CONNECTICUT


                              By:  /s/  Stephen R. Fisher
                                   -----------------------
                                   Name: Stephen R. Fisher
                                   Title: Assistant Secretary


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