Are There Mental Disorders Without Evident Brain Abnormalities?
Yes, the vast majority of mental disorders present without detectable structural brain abnormalities on routine imaging, and current clinical practice explicitly does not require finding brain pathology to diagnose psychiatric conditions. 1
Evidence from Neuroimaging Studies in Psychiatric Patients
The most compelling data comes from systematic evaluation of psychiatric patients undergoing brain imaging:
- In 127 young military recruits with new-onset psychosis, none had clinically significant findings on brain CT scans 1
- In patients with new-onset acute psychosis admitted to psychiatric units, only 1.2% had clinically significant CT findings 1
- A larger study of 397 psychiatric patients without focal neurologic findings detected specific abnormalities in 5%, but all of these abnormalities had no relevance to the patient's psychiatric condition 1
- The pretest probability of finding a space-occupying lesion or any relevant brain abnormality in psychiatric patients was no greater than finding one in the general population 1
Current Clinical Practice Guidelines
The American College of Emergency Physicians (ACEP) explicitly states that routine laboratory and radiographic testing need not be performed in clinically stable psychiatric patients (alert, cooperative, normal vital signs, with noncontributory history and physical examination). 1
The current body of literature supports focused medical assessments where testing is obtained based on specific clinical indicators rather than routine screening, as diagnostic testing is generally low yield, costly, and unlikely to affect disposition or management. 1
When Brain Imaging IS Indicated
Brain imaging should be reserved for patients with:
- Altered mental status or unexplained vital sign abnormalities 1
- New-onset or acute changes in psychiatric symptoms 1
- Abnormal neurological examination findings 2
- Concerning findings on history or physical examination 1
The Conceptual Framework
Recent psychiatric literature emphasizes that mental disorders are characterized by breaches in epistemic, rational, evaluative, emotional, social and moral norms at the person-level, not by identifiable brain lesions. 3 While mental disorders are mediated by brain function, they are not directly attributable to specific brain abnormalities that can be detected with current imaging technology. 4
Psychiatry mainly deals with conditions mediated by brain function but not directly attributable to specific brain abnormalities detectable by laboratory tests or imaging. 4 The reality of psychopathological symptoms—such as hallucinations, depression, anxiety, and compulsions—cannot be questioned, even when structural brain pathology cannot be identified. 4
Important Clinical Caveats
While CNS abnormalities such as oligodendroglioma, glioblastoma, meningioma, intracerebral cysts, and hydrocephalus can present with primarily psychiatric symptoms, these are rare exceptions rather than the rule. 1
The utility of routine brain CT scans in psychiatric patients, especially children and adolescents, is unclear at best, particularly given concerns about long-term radiation exposure effects. 1