5.2. Coexisting Neurodivergent Conditions and Inertial Structures

Autism rarely exists in isolation. Many autistic people also receive diagnoses of ADHD, OCD, anxiety, or other neurodivergent and mental health conditions. However, these co-occurrences are often described as discrete entities rather than expressions of an intertwined cognitive reality. The Monotropic Expansion model reframes these overlaps by highlighting how directionality and inertia shape not only autism, but many of its commonly co-occurring conditions.

In this model, ADHD may be understood as a disinhibited polytropic convergence, where external inputs are rapidly drawn in from multiple directions but not anchored deeply before attention shifts. OCD, by contrast, often manifests as an anxiety-driven variant of monotropic expansion—where context-seeking spirals outward from a single intrusive node, repeating or looping in an attempt to establish internal coherence or control. These models can coexist within a single individual, and their observable expressions may appear contradictory—especially when viewed through the lens of surface behavior.

The Monotropic Expansion framework also opens new interpretive space for conditions not always classified as neurodevelopmental, such as complex PTSD (c-PTSD) and synesthesia. When these conditions co-occur with autism, they may arise not merely in parallel, but as an emergent consequence of monotropic structure. A monotropic individual may experience trauma differently—absorbing context through internal overprocessing, anchoring too deeply to unresolved moments, or failing to re-anchor effectively in the aftermath. Similarly, synesthetic perception—though typically treated as a sensory trait—may reflect the depth and layering of internal associations built through extended contextual expansion. These experiences may be structurally different from how c-PTSD or synesthesia present in non-autistic individuals, and the diagnostic field has yet to meaningfully explore that distinction.

Taken together, these insights support the idea that co-occurring conditions are not always coexisting disorders, but sometimes manifestations of cognitive inertia expressed through different functional systems.