Table 2.

Major categories of validity relevant to the assessment of animal models of BD.

Type of Validity	Description
Homological validity	Appropriateness of the species and strain of the animal model to study aspect(s) of the human mental disorder.
Pathogenic validity	Tendency of the animal model to display pathological processes that resemble those of the human disorder. These pathological processes include early environmental factors that render an organism vulnerable to develop the disorder later in life and triggering factors that impact a vulnerable or a control organism in adulthood and lead to the disorder.
Mechanistic validity	Similarity of the mechanism of disease in the animal model to the actual or hypothesized mechanism underlying the onset/maintenance of the human disorder. The mechanism may be behavioral or neurobiological in nature.
Face validity	Consistency of observations between the animal model and the human disorder, including behaviors and biomarkers.
Predictive validity	Effectiveness of the animal model in mirroring the etiology of disease onset and the response to a therapeutic agent (drug or other treatment) in the human disorder.

These categories and their descriptions were adapted from Belzung and Lemoine [61].