<PAGE>

                                                            EXHIBIT 4.10.1


                 AMENDMENT TO AMENDED AND RESTATED REGISTRATION
                        AND SHAREHOLDER RIGHTS AGREEMENT

      This Amendment to Amended and Restated Registration and Shareholder
Rights Agreement (this "Agreement") is made this 30th day of November, 2000,
by and among American Psych Systems Holdings, Inc., a Delaware corporation
formerly known as American Psych Systems, Inc. (the "Company") and
Canpartners Investments IV, LLC, a California limited liability company
("Canyon"), Nazem & Company IV, L.P. ("Nazem") and Transatlantic Venture
Partners, C.V. ("Transatlantic")(Canyon, Nazem and Transatlantic are
collectively referred to herein as, the "Holders").

                                    RECITALS

      WHEREAS, pursuant to the terms of that certain Note Purchase Agreement and
Warrant Agreement, dated September 26, 1997, by and between the Company and the
Holders (the "1997 Note Purchase Agreement"), the Holders received warrants to
acquire shares of Common Stock from the Company (the "Warrants");

      WHEREAS, pursuant to that certain Registration Rights Agreement dated
September 26, 1997, as amended on December 23, 1998 (the "1997 Registration
Rights Agreement"), by and between the Company and the Holders, the Company
agreed to cause the shares so underlying the Warrants to be registered pursuant
to the Securities Act of 1933, as amended (the "Securities Act");

      WHEREAS, pursuant to the Note and Stock Purchase Agreement dated as of
September 15, 2000 by and among Psych Systems Holdings, Inc., a Delaware
corporation ("Issuer"), Canyon and the Guarantors from time to time a party
thereto (the "2000 Note and Stock Purchase Agreement"), Canyon, as Purchaser,
received shares of Common Stock from the Company (the "Shares");

      WHEREAS, the Holders are parties to a Amended and Restated Registration
and Shareholders Rights Agreement, dated September 15, 2000 (the "Amended and
Restated Agreement"), whereby such parties fully amended and restated in full
the 1997 Registration Rights Agreement and the Company's obligations to cause
the registration of the Registrable Securities (as defined in the 1997
Registration Rights Agreement) pursuant to the Securities Act and to add thereto
Canyon's rights to have the Shares registered thereunder;

      WHEREAS, pursuant to the terms of the 1997 Note Purchase Agreement, Nazem
and Transatlantic purchased 15% Senior Secured Notes in the principal amounts of
$262,829 and $525,657, respectively (the "Notes");

      WHEREAS, pursuant to the terms of the transactions contemplated by that
certain Credit Agreement, dated as of December 23, 1998, among Issuer, the
Company, the lenders listed on the


                                                 American Psych Systems Holdings
                                  Amendment to Amended and Restated Registration
                                               and Shareholders Rights Agreement

<PAGE>

signature pages thereto and NationsCredit Commercial Corporation ("Bank of
America"), Nazem and Transatlantic were each required to convert the principal
and accrued and unpaid interest due under the Notes (the "Conversion") into
shares of the Company's Series II Convertible Preferred Stock ("Series II
Stock");

      WHEREAS, as part of the Conversion, Nazem and Transatlantic were issued
172,464 and 344,928 shares, respectively, of Series II Stock (the "Series II
Shares"); and

      WHEREAS, the Holders desire to amend the Amended and Restated Agreement in
order to include the Series II Shares (and the shares of Common Stock issued and
issuable upon conversion thereof) within the definition of Registrable
Securities thereby expanding the Company's obligations to cause the registration
of the Registrable Securities (as defined in the Amended and Restated Agreement)
pursuant to the Securities Act and to add thereto Nazem's and Transatlantic's
rights to have the Series II Shares registered thereunder.

      NOW, THEREFORE, the undersigned parties, for good and valuable
consideration, the receipt and sufficiency of which is hereby acknowledged, the
parties hereto agree as follows:

      1.    AMENDMENT TO REGISTRATION RIGHTS AGREEMENT.

      (a) The definition of "Holders", as set forth in Section 2.1 of the
Amended and Restated Agreement, shall be deleted in its entirety and the
following shall be inserted in lieu thereof:

            HOLDERS. Except as defined and used in the Preamble and Recitals
above, "Holders" shall mean Canpartners, Nazem & Company IV, L.P. ("Nazem") and
Transatlantic Venture Partners, C.V. ("Transatlantic"), and Transferees of such
Persons' Registrable Securities with respect to the rights that such Transferees
shall have acquired in accordance with Section 9 at such times as such Persons
shall have beneficial or record ownership of Registrable Securities. The Series
II Shares, Shares, Warrant Shares and Warrants held by each Holder on the date
hereof are listed on Schedule I hereto.

      (b) The definition of "Registrable Securities", as set forth in
Section 2.1 of the Amended and Restated Agreement, shall be deleted in its
entirety and the following shall be inserted in lieu thereof:

            REGISTRABLE SECURITIES. "Registrable Securities" shall mean, subject
to Section 9: (i) the Shares, Warrant Shares or Series II Shares owned by
Holders on the date hereof, and owned by a Holder on the date of determination,
(ii) the Warrants, (iii) any securities issued as a dividend or other
distribution with respect to, or in exchange by the Company generally for, or in
replacement by the Company generally of, such Registrable Securities; and (iv)
any securities issued in exchange for Registrable Securities in any sale,
exchange, merger or reorganization of the Company; provided, however, that
Registrable Securities shall not include any securities


                                      2

                                                 American Psych Systems Holdings
                                  Amendment to Amended and Restated Registration
                                               and Shareholders Rights Agreement

<PAGE>

which have theretofore been registered and sold pursuant to the Securities Act
or which have been sold to the public pursuant to Rule 144 or any similar Rule
promulgated by the Commission pursuant to the Securities Act. For purposes of
this Agreement, a Person will be deemed to be a holder of Registrable Securities
whenever such Person has the then-existing right to acquire such Registrable
Securities (by conversion, subscription or otherwise), whether or not such
acquisition has actually been effected.

      (c) A new definition of "Senior Notes" shall be added to Section 2.1 of
the Amended and Restated Agreement and shall read as follows:

            SENIOR NOTES. "Senior Notes" shall mean those 15% Senior Secured
Notes, dated September 26, 1997, issued to (i) Nazem in the aggregate principal
amount of $262,829, and (ii) Transatlantic in the aggregate principal amount of
$525,657, which Senior Notes (including principal and accrued and unpaid
interest due thereunder) were converted into shares of the Company's Series II
Convertible Preferred Stock on December 23, 1998, pursuant to the terms of the
transactions contemplated by that certain Credit Agreement, dated as of December
23, 1998, among Issuer, the Company, the lenders listed on the signature pages
thereto and Bank of America.

      (d) A new definition of "Series II Shares" shall be added to Section 2.1
of the Amended and Restated Agreement and shall read as follows:

            SERIES II SHARES. "Series II Shares" shall mean (i) the shares of
Series II Convertible Preferred Stock issued to Nazem and Transatlantic in
connection with the conversion of the Senior Notes and (ii) any securities
issued with respect to any of such shares or other securities referred to in
clause (i) above upon the conversion thereof into other securities or by way of
stock dividend or stock split or in connection with a combination of shares,
recapitalization, merger, consolidation or other reorganization or otherwise;
PROVIDED that such securities shall cease to be Series II Shares when such
securities shall have (x) been disposed of pursuant to a Public Sale or (y)
cease to be outstanding.

      (e) Schedule I, as attached to the Amended and Restated Agreement, shall
be deleted in its entirety and a new Schedule I, as attached hereto, listing the
Series II Shares, Shares, Warrant Shares and Warrants held by each Holder, as
defined in Section 1(a) above, as of September 15, 2000, shall be inserted in
lieu thereof.

      2. EFFECT OF AMENDMENTS. Except for the amendment of the Amended and
Restated Agreement under Section 1 above, all of the terms and conditions of the
Amended and Restated Agreement remain unmodified and in full force and effect.
This Agreement shall not be effective until and unless the Holders have executed
this Agreement.

      3. EXECUTION IN COUNTERPARTS.  This Agreement may be executed in
counterparts, which together shall constitute one and the same instrument.


                                       3

                                                 American Psych Systems Holdings
                                  Amendment to Amended and Restated Registration
                                               and Shareholders Rights Agreement

<PAGE>

      IN WITNESS WHEREOF, the parties hereto have executed this agreement as of
the day and year first above written.


                                         CANPARTNERS INVESTMENTS IV, LLC,
                                         A California limited liability company

                                         By:  Canpartners Incorporated,
                                               a California corporation,
                                               its managing member


                                         By:
                                               ---------------------------------
                                         Name:
                                               ---------------------------------
                                         Title:
                                               ---------------------------------
                                         NAZEM & COMPANY IV, L.P.


                                         By:  Nazem & Associates IV, L.P.,
                                               a Delaware limited partnership,
                                               its general partner


                                         By:    /s/ Philip Barak
                                               ---------------------------------
                                         Name:  Philip Barak
                                               ---------------------------------
                                         Title: General Partner
                                               ---------------------------------

                                         TRANSATLANTIC VENTURE PARTNERS, C.V.

                                         By:  The Banexi-Nazem Transatlantic
                                               Venture Fund N.V.,
                                               a Netherlands Antilles
                                               corporation,
                                               its general partner

                                         By:    /s/ Philip Barak
                                               ---------------------------------
                                         Name:  Philip Barak
                                               ---------------------------------
                                         Title: Investment Manager
                                               ---------------------------------


                              Signature Page 1 of 2

                                                 American Psych Systems Holdings
                                  Amendment to Amended and Restated Registration
                                               and Shareholders Rights Agreement

<PAGE>


                                         AMERICAN PSYCH SYSTEMS HOLDINGS, INC.,
                                               a Delaware corporation



                                         By:   /s/ Stephen DaRe
                                               ---------------------------------
                                         Name: Stephen DaRe
                                               ---------------------------------
                                         Title: EVP & CFO
                                               ---------------------------------


                              Signature Page 2 of 2

                                                 American Psych Systems Holdings
                                  Amendment to Amended and Restated Registration
                                               and Shareholders Rights Agreement

<PAGE>

                                   SCHEDULE I

                        TO REGISTRATION RIGHTS AGREEMENT

HOLDER:                                   SERIES II SHARES, SHARES, WARRANT
AND WARRANTS                              SHARES
--------------------------------------------------------------------------------

CANPARTNERS INVESTMENTS IV, LLC          750,000 Shares
-------------------------------          1,183,928 Warrant Shares

Address:
      c/o Canyon Partners Incorporated
      9665 Wilshire Boulevard, Suite 200
      Beverly Hills, California 90212
      Attn: Scott A. Imbach
      Telecopy: 310/247-2701
--------------------------------------------------------------------------------
NAZEM & COMPANY IV, L.P.                 172,464 Series II Shares
------------------------                 38,691 Warrants

Address:
      645 Madison Avenue, 12th Floor
      New York, New York 10022
      Attention:  Phil Barak
--------------------------------------------------------------------------------
TRANSATLANTIC VENTURE PARTNERS, C.V.     344,928 Series II Shares
------------------------------------     77,381 Warrants


Address:
      645 Madison Avenue, 12th Floor
      New York, New York 10022
      Attention:  Phil Barak
--------------------------------------------------------------------------------