For all its frequent fluff and triviality, television can sometimes touch viewers more deeply, as illustrated by a pair of programs tonight, both on the subject of Alzheimer's disease:
* ABC's popular "Full House" (at 8 p.m., Channel 13) is tagged with the overt intention of encouraging teen viewers to consider volunteering their time to help others.
The episode has 15-year-old D.J. (Candace Cameron) becoming involved in an "adopt-a-grandparent" program at a nursing home. The network says the sequence is patterned after one of the most frequent activities of the 58 percent of American teens who really do volunteer in some form of community service.
Whitman Mayo guest stars as D.J.'s adopted elder, and the teen must discover and then cope with the sad and frightening reality that his new friend suffers from Alzheimer's disease.
* And at 10 p.m. on the HBO premium cable service, a new "America Undercover" documentary sensitively but relentlessly portrays the reality of Alzheimer's, a progressive disease now suffered by some 4 million victims in the United States.
Sharp portraits of five afflicted individuals and their families are sometimes almost too intimate to watch, clearly showing that in many cases family members are also victims of the disease.
"They are our mothers, fathers, sisters and brothers, lost in space and time forever," says the narration. (One of the two narrators is identified as Yasmin Aga Khan, daughter of actress Rita Hayworth, who died from Alzheimer's.)
A teen son, for example, breaks down in talking about his musician father. Diagnosed at the age of 58, the man no longer remembers what shoelaces are, or how to distinguish between a radio and an electric razor, but seems otherwise healthy.
His wife, after five years of care giving, finally takes a breather by entering her husband in a temporary residential program. She and her son are palpably relieved as they leave the facility, but we see the man talking sadly to the documentary film team, asserting "I feel that I still have some worth."
Among the other subjects are an Alzheimer's sufferer who lives alone, filling her house with cardboard boxes and other trash, and a woman who tries to talk to her own image in a mirror, believing it to be another person.
Unfortunately the documentary -- produced, written and directed by Michael Mierendorf -- has little hope to offer. In 50 years, it projects the number of victims will be triple today's level, yet at the moment no effective treatment exists to inhibit the progress of the disease.
But the show includes resource information for families, including a 24-hour referral line to the Alzheimer's Association. In addition, HBO says the documentary will be added to its Project Knowledge collection for the use of schools and libraries.