(1) As used in this chapter, “person requiring treatment” means (a), (b), or (c):

    (a) An individual who has mental illness, and who as a result of that mental illness can reasonably be expected within the near future to intentionally or unintentionally seriously physically injure himself, herself, or another individual, and who has engaged in an act or acts or made significant threats that are substantially supportive of the expectation.

    (b) An individual who has mental illness, and who as a result of that mental illness is unable to attend to those of his or her basic physical needs such as food, clothing, or shelter that must be attended to in order for the individual to avoid serious harm in the near future, and who has demonstrated that inability by failing to attend to those basic physical needs.

    (c) An individual who has mental illness, whose judgment is so impaired by that mental illness, and whose lack of understanding of the need for treatment has caused him or her to demonstrate an unwillingness to voluntarily participate in or adhere to treatment that is necessary, on the basis of competent clinical opinion, to prevent a relapse or harmful deterioration of his or her condition, and presents a substantial risk of significant physical or mental harm to the individual or others.

    (2) An individual whose mental processes have been weakened or impaired by a dementia, an individual with a primary diagnosis of epilepsy, or an individual with alcoholism or other drug dependence is not a person requiring treatment under this chapter unless the individual also meets the criteria specified in subsection (1). An individual described in this subsection may be hospitalized under the informal or formal voluntary hospitalization provisions of this chapter if he or she is considered clinically suitable for hospitalization by the hospital director.