Summary of neurobiological factors implicated in OCD, hypothesized mechanism by which they exert an effect on OCD, and the section number where the relevant research is discussed
| Implicated Factor | Hypothesized Mechanism | Section |
|---|---|---|
| Serotonin neurotransmission | Neurotransmitter deficit | III.A.1 |
| Low 5-HT transporter | ||
| Altered function of 5-HT1A receptors | ||
| Hypofunction of 5-HT2C receptors | ||
| Dopamine neurotransmission | D2 and/or D1 receptor activity | III.A.2 |
| Interaction with serotonin | ||
| Glutamate and GABA neurotransmission | Altered glutamate concentration | III.A.3 |
| Faulty glutamate transporters | ||
| GABA-glutamate imbalance | ||
| Oxidative stress | Increased lipid peroxidation | III.B.1 |
| Disturbances in cortical GSH | ||
| Phosphoinositide hyperactivity | Insufficient MI | III.B.2 |
| NO-cGMP pathway | Increased levels of NO | III.B.2 |
| cAMP-dependent pathway | Supersensitive AC activity | III.B.2 |
| Increased PDE4 activity | ||
| Brain-gut-microbiota axis | Specific alterations in the gut microbiome | III.B.3 |
| Altered metabolism in the TRYCAT pathway | ||
| Neurosteroid dysregulation | Modified gene expression and neuronal excitability | III.B.4 |
| Oxytocin | Activates threat detection circuits | III.B.4 |
| Neurotrophic factors | BDNF reduced, possibly due to genetics | III.B.5 |
| Regional neuroanatomical changes | Alteration of a circuit composed of cortex-basal ganglia-thalamus-cortex pathways | III.C. |
| Specific genes or polymorphisms | Result in alterations of serotonergic, dopaminergic, and glutamatergic signaling | III.D.1 |
| Age of onset | Childhood onset may be distinct | III.D.2 |
| Sex hormones | Alter serotonin neurotransmission | III.D.3 |
| Stressful life events | Induction of HPA hyperactivity | III.D.3 |
| Streptococcal infection | Altered immune function | III.D.4.a |
| Other infections, autoimmune and inflammatory processes | Glutamate neuro-excitotoxicity | III.D.4.a |
| Antibodies crossreact with brain antigens | ||
| Microglia activation | ||
| Change in TRYCAT metabolism | ||
| Disease-avoidance behavioral adjustments | ||
| Neuroinflammation | Cascade of cumulative responses | III.D.4.b |