As the Twitter audience continues to mushroom -- up to 21 million US visitors in July alone -- the younger age groups are the ones flooding in the fastest, said ComScore.
The data shows that the number of visitors from every age segment is growing, but the most notable positive shifts are evident among the 12 to 17 and 18- to 24-year-old segments, which are coming at the expense of the 35 and overs.
ComScore analyst Andrew Lipsman blames Ashton Kutcher for skewing the demographics in favour of the youngsters.
Lipsman said: "I think that during the early adopter period back in 2008, Twitter was first gaining notoriety in business settings and via news outlets -- particularly on CNN, which resulted in an older-skewing early adopter profile.
"But as Twitter began to filter more into the mainstream, along with it came a culture of celebrity as Shaq, Britney Spears and Ashton Kutcher joined the ranks of the Twitterati."
ComScore warns of an "impending youth invasion". As more celebrities take up tweeting, so will more young people, creating a "virtuous cycle".
Lipsman said: "Twitter is most definitely popular among younger users and I don't see that changing anytime soon.
"They are fuelling its continued growth and pushing it ever closer to achieving critical mass.
"If that happens, it will be the first example I can think of where the younger demographics were not the critical early adopters of a new internet technology yet still played a vital role in its adoption curve. But it won't be the last."