<i>&quot;I believe many mental illnesses ... can be characterized as contagious.&quot;</i><p>I can believe that.<p>Social cognition, attachment theory, mirror neurons, etc.<p>Swarm Intelligence has (for its time?) a great primer on social cognition, how our brains resonate with each other, how children use their parent&#x27;s brains and emotions to regulate their own, etc. <a href="http:&#x2F;&#x2F;www.swarmintelligence.org&#x2F;SIBook&#x2F;SI.php" rel="nofollow">http:&#x2F;&#x2F;www.swarmintelligence.org&#x2F;SIBook&#x2F;SI.php</a><p>I lived with a paranoid schizophrenia. It started making me crazy too. Took months to shake that off.<p>And I can definitely confirm that anxiety is contagious, from personal experiences.