Display screen or portion thereof with a transitional mental health graphical user interface

[0001]FIG. 1 is a first image of a display screen or portion thereof with a transitional mental health graphical user interface showing my new design;

[0002]FIG. 2 is a second image thereof;

[0003]FIG. 3 is a third image thereof;

[0004]FIG. 4 is a fourth image thereof; and,

[0005]FIG. 5 is a fifth image thereof.

[0006]The broken lines and broken line text in FIGS. 1-5 illustrate portions of a display screen or portion thereof with a transitional mental health graphical user interface and form no part of the claimed design. The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-5. The process or period in which one image transitions to another image forms no part of the claimed design. The stippling patterns of FIGS. 2, 3, 4, and 5 illustrate a contrast in appearance.