Introduction: Disorders are split into three main groups: mostly rapid onset, variable onset, and insidious onset. Within each of these categories, disorders are furthers classified using the VITAMINSCDE system, corresponding to the following: Vascular, Infection, Trauma, Autoimmune, Mental Health, Idiopathic/Iatrogenic, Neoplasia, Substance/Medications/Toxins, Alcohol, Behavioral/psychosomatic, Congenital, Degenerative, Endocrine/Metabolic. Each disorder will have the following sections of varying length depending on the prevalence of the disorder and amount of information known: Definition, Prevalence, Physiological underpinnings, Subtypes, Typical Course, Expectations for neuropsychological testing, Rule Outs, and Recommendations. The goal is to provide very brief, yet comprehensive information that can aid in rapid differential diagnosis and allow for more thorough follow-up if needed.  Part 1: Disorders of Mostly Rapid Symptom Onset  1. Vascular o Stroke o Subarachnoid Hemorrhage 2. Infection o Syphilis o HSV-1 o Prion Disorders o Meningitis  o Encephalitis o Abscess  o PML o ADEM 3. Trauma o TBI o Hypoxia 4. Idiopathic/Iatrogenic o Delirium  5. Neoplasia o Paraneoplastic syndrome 6. Substance/Medications/Toxins o Withdrawal  o Serotonin syndrome o Neuroleptic malignant syndrome 7. Alcohol o Hepatic Encephalopathy 8. Behavioral/psychosomatic o Psychogenic Non-Epileptic Seizures o Malingering 9. Congenital o Acute Intermittent Porphyria 10. Endocrine/Metabolic o Hypothyroidism  o Hypoglycemia  Part 2: Disorders of variable symptom onset  11. Vascular o Stenosis 12. Infection o Lyme disease o Systemic lupus erythematosus 13. Trauma o Subdural hematoma 14. Autoimmune o Multiple Sclerosis 15. Mental Health o Mood disorders o Anxiety/Hypochondriasis o Psychotic Disorders 16. Idiopathic/Iatrogenic o Epilepsy o Sarcoidosis 17. Neoplasia o Tumor o Metastases  18. Substance/Medications/Toxins o Toxins o Medication side effects o Long-term drug use 19. Behavioral/psychosomatic o Somatoform  20. Degenerative o Hydrocephalus  21. Endocrine/Metabolic o Vitamin deficiency o Hashimoto's encephalopathy  Part 3: Disorders of Mostly Insidious Symptom Onset  22. Vascular o Vascular dementia o Binswanger's 23. Autoimmune o HIV Associated Neurocognitive Disorder 24. Substance/Medications/Toxins o End Stage Renal Disease o Liver disease 25. Alcohol o Wernicke-Korsakoff Syndrome o Alcohol-Related Dementia 26. Congenital o Wilson's disease o CADASIL 27. Degenerative o Alzheimer's disease o Frontotemporal Dementias o Dementia with Lewy Bodies o Progressive Supranuclear Palsy o Parkinson's disease o Huntington's disease o Corticobasal degeneration o Multiple System Atrophy 28. Endocrine/Metabolic o Cushing's syndrome o Mitochondrial encephalopathy