Identifying Cerebral Hemodynamic Patterns in Mood Disorders and Mild Cognitive Impairment: A Functional Near-Infrared Spectroscopy (fNIRS) Study

Inclusion Criteria

General Inclusion Criteria (across all diagnostic groups):

* 18 years and older
* Ability to provide written informed consent
* Adequate cognitive and language abilities to understand and complete study tasks, including clinical assessments and fNIRS procedures
* Confirmed clinical diagnosis of major depressive disorder, bipolar disorder, or mild cognitive impairment (MCI)
* Stable psychiatric or cognitive condition, without acute episodes requiring immediate intervention

Specific Inclusion Criteria (for diagnostic groups):

* Healthy control

  o No past or current psychiatric or cognitive disorder
* Major depressive disorder (MDD):

  * Diagnosis of major depressive disorder, confirmed through clinical evaluation.
  * No history of bipolar disorder or psychotic symptoms.
* Bipolar disorder:

  o Diagnosis of bipolar disorder I or II, confirmed through clinical evaluation.
* Mild Cognitive Impairment (MCI):

  * Pre-existing clinical diagnosis of mild cognitive impairment, supported by neuropsychological testing and/or MRI, PET scan data.
  * No history of major psychiatric disorders, such as major depression, bipolar disorder or schizophrenia.

Exclusion Criteria

General Exclusion Criteria (across all diagnostic groups):

* Active primary psychotic or substance use disorders (except nicotine dependence) within the past year
* Any severe or unstable medical condition that could interfere with participation or data collection
* Any active neurological condition (including seizure disorder, traumatic brain injury, stroke) that could affect cognitive functioning or brain imaging results
* Inability to comply with study procedures, including cognitive testing, fNIRS assessment, or other assessments required by the protocol
* Pregnant women will be excluded due to potential physiological changes that could affect study outcomes

Specific Exclusion Criteria (for diagnostic groups):

* Healthy control

  o Any past or current psychiatric or cognitive disorder
* Major depressive disorder (MDD):

  * Diagnosis of bipolar disorder or schizophrenia.
  * Brain stimulation therapy within the past 3 months.
* Bipolar disorder:

  o Diagnosis of schizophrenia or schizoaffective disorder.
* Mild Cognitive Impairment (MCI):

  * Diagnosis of dementia.
  * Significant cognitive impairment preventing understanding or completion of study tasks.