Stronger inner speech links to higher depression, anxiety, OCD, eating disorders, PTSD, drug addiction, borderline, bipolar, autism, ADHD. Mental illness factor score rises linearly with inner speech strength. Women report stronger inner speech than men. Gays and non-monogamists have stronger inner speech. Leftists and atheists show stronger inner speech. Effective altruists have prominent inner speech. Finance and IT professionals have weaker inner speech. Unhappiness increases linearly with inner speech. Paranoia and hearing voices rise linearly with inner speech. No race differences in inner speech. No IQ correlation in high-IQ sample. Age negatively correlates with inner speech. Relationship holds after controlling for age, gender, sexual orientation. Effect is linear, not non-monotonic. Single question measure underestimates true inner speech effects. Sample from Scott Alexander readers, mean IQ 140.