Sixty-five adults participated in the study.
They provided the researchers writing samples and reports of the time spent reading various books, newspapers and websites.
Using an algorithmic tool, the researchers compared the quality of participants' writing samples to samples taken from the books, newspapers and websites the participants most read.
The comparisons show a strong correlation between reading and writing skills: people who read more complex stories have more complex writing, and vice versa.
The researchers blamed junk peddlers like Reddit and Tumblr for participants' worst writing habits.
Consumption of content rife with jargon, slang and shorthand threatens an adult's ability to compose complex sentences.
Neuroanatomy is also to blame.
"Neuroanatomy may predispose even adults to mimicry and synchrony with the language they routinely encounter in their reading, directly impacting their writing," the researchers say.