Examining Neurobiological Mechanisms Underlying the Therapeutic Effect of the Ketogenic Diet in Bipolar Disorder (BD)

Inclusion Criteria: All participants: *18-30 years of age BD hypomanic group (n=30): Meeting sex proportion: 50% female Meeting diagnosis proportion: 50:50% Bipolar I: Bipolar II (BDI:II) (Diagnostic and Statistical Manual of Mental Disorders 5; DSM-5) Young Mania Rating Scale score(YMRS)>10 Score <8 Hamilton Rating Scale for Depression(HRSD) BD medications will be allowed as in our previous studies: any combination of atypical antipsychotics, lithium, antidepressants, anxiolytics (common in BD) BD euthymic group (n=30): Meeting sex proportion: 50% female Meeting diagnosis proportion: 50:50% BDI:II (DSM-5) Score <8 on YMRS Score <8 on Hamilton Depression Rating Scale (HRSD) BD medications will be allowed as in our previous studies: any combination of atypical antipsychotics, lithium, antidepressants, anxiolytics (common in BD) Healthy Control (HC) Group (n=30): Sex matched with BD groups No psychiatric history Exclusion Criteria: All participants: Not between 18-30 years of age History of head injury, neurological, pervasive developmental disorder (e.g. autism), systemic medical disease and treatment (medical records, participant report) Mini-Mental State Examination score (cognitive state) <24 Premorbid National Adult Reading Test Intelligent Quotient (NAART IQ) estimate<85 Visual disturbance: <20/40 Snellen visual acuity Left/mixed handedness (Annett criteria) History of alcohol/substance use disorder (SUD; all substances, including nicotine), and/or illicit substance use (except cannabis) over the last 6 months (SCID-5). Note: lifetime/present cannabis use (at non-abuse (<3 times in the past month) and non SUD levels) will be allowed, given its common usage in BD and young adults. Cannabis SUD over the last 6 months will not be allowed. Urine tests on scan days will exclude current illicit substance use (except cannabis). Salivary alcohol tests on scan days will exclude intoxicated individuals MRI exclusion: metallic objects, e.g., surgical implants; claustrophobia; positive pregnancy test for females or self-report pregnancy Unable to understand English Conditions related to the pancreas, liver, thyroid or gallbladder. Does not have a smartphone with a) iPhone operating system (iOS) version 12.0 or above, or b) Android version 8 and later to use with the Keto-Mojo app BD hypomanic group: Must be meeting sex proportions: not 50% female Must be meeting diagnosis proportions: not 50:50% BDI:II (DSM-5) Diagnosis of BD in a depressive, manic, or euthymic episode Young Mania Rating Scale score(YMRS)10 or lower Score 8 or higher on Hamilton Rating Scale for Depression(HRSD) Using psychotropic medications other than those allowed in inclusion criteria Head circumference larger than about 58 cm (size restriction of 7Tesla (7T) scanner) BD euthymic group: Not meeting sex proportion: not 50% female Not meeting diagnosis proportion: not 50:50% BDI:II Diagnosis of BD in a depressive, hypomanic, or manic episode Score 8 or higher on YMRS Score 8 or higher on HRSD Using psychotropic medications other than those allowed in inclusion criteria Healthy Control (HC) Group Not sex-matched with BD groups Has psychiatric history