Why did Marlon spend most of the 1980s on the sidelines?

Looking at his filmography, Marlon Brando only made two films in the '80s, 1980's The Formula and 1989's A Dry White Season. That's of course, a nine year break in-between film appearances.
In comparison, Marlon in the '90s did seven films in-between 1990 and 1998.

https://en.wikipedia.org/wiki/Marlon_Brando_filmography

Before this, the longest that Marlon went in-between movies was the four year interval between 1972's Last Tango in Paris and 1976's The Missouri Breaks.