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March 4, 1998

VIA HAND DELIVERY

Thomas H. Aasen
17823 Toltec Court
San Diego, CA  92127

Dear Tom:

As discussed, I am pleased to offer you the position of Vice President - Chief
Financial Officer of ACADIA Pharmacuticals Inc. I firmly believe that with your
joining our team, ACADIA Pharmaceuticals will have the potential to not only
quickly surpass such short term goals as completing additional significant
corporate partnerships and a successful public offering, but that we will be
able to flourish in facing the challenges to be met in the years ahead as we
build an extremely valuable, technology driven, integrated drug discovery
company. All of us associated with ACADIA Pharmaceuticals look forward to
working with you. The terms of our offer are as follows:

1.       Your title will be Vice President - Chief Financial Officer (or in such
         other position as the Company or its Board may determine) and you will
         report to the Chief Excutive Officer of the Company. As discussed, you
         will be a key member of the senior management team and you will be
         involved in virtually all important decisions on the strategy and
         future operations of the Company. Your initial duties will encompass
         all financial matters as well as legal, human resources, and other
         matters. You agree to devote all of your business time, attention and
         energies to the business of the Company.

2.       Your initial annual salary will be $160,000, subject to adjustment as
         determined by the Board as of January 1 of each year.

3.       You will be eligible to receive an annual bonus with a target of 20% of
         the base salary you receive in each calendar year payable within 90
         days of the end of such Calendar year. The amount of the annual bonus
         will be determined by the Board of Directors based upon your individual
         performance and the financial performance of the Company.

4.       The Company will also provide you a signing bonus of $20,000 payable
         immediately after your beginning employment with ACADIA Pharmaceuticals
         Inc. You agree to return such bonus to the Company if you voluntarily
         terminate your employment within six months of the start date of your
         employment.

5.       Naturally, what I consider to be the most important part of your
         compensation is your participation in the Company's stock option plan.
         You will receive stock options that


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         will vest 25% after 12 months of employment with additional vesting of
         1/48% after each additional month of employment through your 48th
         month of employment with the Company. The stock options that you will
         be entitled to, subject to the aforementioned vesting schedule and
         other terms of the plan, will be equal to options to purchase 75,000
         shares of common stock of the Company. The exercise price at which
         these options will be issued will be equal to the fair market value of
         the common shares of the Company at the date of grant of the options,
         which will be the start date of your employment. In the event the
         company is acquired or completes an Acquisition Event as defined in
         the Company"s 1997 Stock Option Plan, any unvested options you then
         hold will be immediately vested, subject to your continued employment
         for a period of at least six months following the completion of the
         Acquisition Event if so requested by the Company. Enclosed is a copy
         of the ACADIA Pharmaceuticals 1997 Stock Option Plan. Note that there
         are currently approximately 7.4 million common equivalent shares
         outstanding, fully diluted for the shares reserved for the 1997 Stock
         Option Plan.

6.       In the event the Company terminates your employment, other than for
         cause as defined below, you will receive severance in the form of the
         continuation of your salary for the one year period following the
         termination of your employment plus the benefits you were receiving at
         the time of your termination (subject to the terms of the Company's
         benefit plans).

         For purposes of the above, "cause" for termination shall be deemed to
         exist upon (a) a good faith finding by the Company of material failure
         of the Employee to perform his assigned duties for the Company,
         dishonesty, gross negligence or other material misconduct, or (b) the
         conviction of the Employee of, or the entry of a pleading of guilty or
         nolo contendere by the Employee to, any crime involving moral turpitude
         or any felony.

7.       You will be provided all of the standard company benefits, including
         four weeks paid vacation, health insurance, group term life and
         accidental death and dismemberment insurance, group disability
         insurance, travel accident insurance, and the ability to participate in
         the Company's 401k plan which includes matching of employees'
         contributions to the plan up to 5% of compensation. Enclosed is
         information regarding the Company's various benefit programs.

         With respect to the Company's matching of contributions to the 401k
         Plan up to 5% of compensation, note that it is the intention of the
         Company to provide the 5% payment to all employees interested in
         deferring 5% of their compensation even if their deferrals to the 401k
         plan are otherwise limited to less than 5% of total compensation due to
         various IRS rules. After you join the Company, and with your input, we
         can conclude on an appropriate non-qualified or other arrangement in
         this regard.

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8.       As a condition of your employment you will be required to agree to and
         sign the Company's standard Disclosure and Inventions Agreement, a copy
         of which is attached.

9.       The start date for your employment will be April 1, 1998 or other
         mutually agreeable date.

Tom, I am very confident that your joining the ACADIA team will prove extremely
beneficial to both you and the Company and its shareholders. If you have any
questions, please do not hesitate to call me at the office or at home, my home
number is (619) 793-4674. We would appreciate receiving your response to this
offer by March 9, 1998.

Sincerely yours,

/s/ Mark R. Brann

Mark R. Brann, Ph.D.
Founder, Chief Executive and Scientific Officer and President


I accept your offer to become Vice President - Chief Financial Officer of ACADIA
Pharmaceuticals Inc. in accordance with the terms included above:


Signature: /s/ Thomas H. Aasen                   Date: March 9, 1998
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                Thomas H. Aasen