In order to validly execute a Will, the testator has to "have capacity". The law says, "Any person eighteen years of age or older, and of sound mind, may dispose of his estate by will". Conn. Gen. Stat. § 45a-250. That is, he has to be of sound enough mind to direct where his property will go.
In Connecticut, estate planning lawyers know that the test for testamentary capacity is “whether the testator had mind and memory sound enough to know and understand the business upon which he was engaged at the time of execution.” City National Bank and Trust Co.'s Appeal, 145 Conn. 518, 521, 144 A.2d 338 (1958).
Moreover, will lawyers know that testamentary capacity is assessed at the time the instrument is executed, and not on the testator's ability to remember the contents of the instrument.
So, a person has to be in good shape mentally to make a Will. One of the primary grounds for attacking or invalidating a Will, is lack of capacity. A good estate planning lawyer incorporates an assessment of capacity into his will execution game plan.