A woman losing her mind is a terrible thing to watch, but the splendid acting in "Still Alice" makes it worth the pain. Scarier than any Elm Street nightmare, a horror film for the rest of us, it succeeds despite itself — not because of one strong performance but two.

‘STILL ALICE’ Rated: PG-13 Opens Friday at Dole Cannery Stadium 18 and Kahala 8

The accomplished Julianne Moore stars as respected academic Alice Howland, shocked by her diagnosis of early-onset Alzheimer’s disease, and the actress’ work as someone coping with the ravages of the unthinkable deserves all the plaudits it’s going to get.

But if it wasn’t for co-star Kristen Stewart, who plays Alice’s daughter Lydia, "Still Alice" wouldn’t be nearly as emotionally effective as it is. Moore and Stewart have been off-screen friends for more than a decade, and that bond only enhances the work they do here.

As scripted by the writer-director team of Richard Glatzer and Wash Westmoreland from a novel by Lisa Genova, "Still Alice" does have obstacles to overcome. Elements of its plot have the standard quality of a Hallmark production, and the work of some of the film’s other co-stars is a bit too on the nose. But with Moore and Stewart on the case, we feel the presence of something real here, something that can’t be ignored.

Alice is introduced at the usual cinematic happy event where no one realizes it’s going to be all downhill from here. It is the 50th birthday celebration for this celebrated Columbia University professor of linguistics, with her loving if a trifle overbearing husband John (Alec Baldwin) and two of her three adult children (Kate Bosworth, Hunter Parrish) present at a Manhattan restaurant to raise a glass.

Not attending is third daughter Lydia (Stewart), an aspiring actress who lives out in Los Angeles. Alice uses the opportunity of a speaking engagement at UCLA to look in on Lydia and to express, clearly not for the first time, her frustration that this daughter has chosen not to go to college in favor of following her passion.

One pleasure of "Still Alice" at this early stage is the chance it gives us to see Moore playing a happy, well-adjusted woman. The actress is so good at aberrational characters that we don’t get enough chances to see her playing normal yet still involving, which is nowhere near as easy as it may sound.

But "Still Alice" is not about staying normal to the last frame. Like viewers of "Titanic" who know that the ship is destined to sink without a trace, we wait for that first indication — it turns out to be a memory lapse at that UCLA talk — of the decline we know is inevitable.

Alice shrugs that one off, but back in New York things get worse, and when she finds herself disoriented jogging near her home, a visit to a neurologist is unavoidable.

The eventual diagnosis is as shocking as it is incontrovertible, with this being a hereditary condition Alice might have passed on to her children making things only worse. The heart of "Still Alice" is the wrenching business of watching as all the things that define this woman to herself and her family gradually drain away, one by one by one.

Moore is especially good at the wordless elements of this transformation, allowing us to see through the changing contours of her face — what it is like when your mind empties out. When Alice says at one point, "I feel like I can’t find myself," it is all the more upsetting because we’ve already watched it happen.

"Still Alice" does have situations that feel contrived, which is why the film is especially fortunate to have not only Moore but also Stewart to keep things honest.

As she showed working with Juliette Binoche in "Clouds of Sils Maria," Stewart is especially good at going toe to toe and holding her own with veteran actresses, and the intensity she brings to the part of a daughter determined to do things her own way is essential here.

Though it doesn’t say so in so many words, "Still Alice" wants you to remember that its title is only one letter off from "Still Alive." Alice is struggling to be who she once was, and that is a battle we have to respect.

Review by Kenneth Turan, Los Angeles Times