When Mood Meets Neurodevelopment: Understanding the Overlap Between Bipolar Disorder and Autism Spectrum Disorder

Bipolar disorder (BD) and autism spectrum disorder (ASD) are often viewed as separate conditions, yet research increasingly suggests that they can overlap in important ways. Individuals with both conditions may experience more severe mood symptoms, greater social difficulties, and higher rates of psychiatric hospitalization than those with either diagnosis alone.

BD is characterized by episodes of mania, hypomania, and depression. Symptoms can include elevated mood, decreased need for sleep, racing thoughts, impulsivity, irritability, and periods of profound sadness or hopelessness. ASD is a neurodevelopmental condition involving differences in social communication, sensory processing, repetitive behaviors, and restricted interests.

Although they are distinct diagnoses, research suggests that people with ASD are more likely than the general population to develop BD. A 2022 systematic review found that approximately 7.5% of autistic adults also met criteria for BD, which is substantially higher than the roughly 1% to 2% lifetime prevalence of BD in the general population (Varcin et al., 2022). Psychosis also appears to be more common in autistic adults, with one review finding a pooled prevalence of 9.4% (Varcin et al., 2022).

Some studies suggest that autistic traits are also common in people with BD, even when they do not meet full criteria for ASD. One study found that 42.7% of people with bipolar disorder showed elevated autistic traits or features associated with the broader autism phenotype (Dell'Osso et al., 2019). Those individuals tended to have an earlier onset of BD and longer hospital stays.

Part of the overlap between BD and ASD may be genetic. Both conditions are highly heritable, meaning that genes play a significant role in risk. Genome-wide association studies have found that several genes and chromosomal regions appear to contribute to both autism and bipolar disorder.

One of the most studied genes is CACNA1C, which affects calcium channels involved in communication between brain cells. Variants in CACNA1C have been associated with BD, schizophrenia, depression, and other psychiatric conditions. Researchers believe disruptions in this gene may affect emotional regulation, attention, memory, and cognitive flexibility (Fiorentino et al., 2014).

Another important gene is ANK3, which plays a role in neuron structure and the regulation of sodium channels in the brain. Researchers have repeatedly linked ANK3 to BD, but they have also observed mutations and disruptions in this gene in autism. Researchers believe ANK3 may contribute to difficulties in emotional regulation, sensory processing, and cognitive function (Ferreira et al., 2008).

More broadly, studies suggest that BD and autism share risk in pathways involving calcium signaling, ion channels, and synaptic functioning. Shared genetic variations have also been identified in regions such as 16p11.2, a chromosomal area associated with autism, schizophrenia, and other neurodevelopmental conditions (Imbrici et al., 2013).

Clinically, BD and ASD can look similar in several ways, which can make diagnosis difficult. Both conditions may involve irritability, emotional dysregulation, sleep problems, impulsivity, sensory sensitivity, social difficulties, and unusual speech patterns. Individuals with ASD may appear highly energetic, talkative, or intensely focused on special interests, which can sometimes resemble mania. Conversely, someone in a manic episode may display poor social awareness, rapid speech, or unusual behavior that resembles autism (Vasconcelos-Moreno et al., 2025).

However, there are important differences. In autism, social communication difficulties and repetitive behaviors are usually lifelong and begin in early childhood. In BD, mood symptoms tend to occur in episodes and represent a change from a person’s usual functioning. Mania is typically marked by decreased need for sleep, grandiosity, increased goal-directed behavior, and elevated or irritable mood (Vasconcelos-Moreno et al., 2025).

Having both ASD and BD can complicate treatment. People with autism and BD may be more sensitive to the side effects of medications, more likely to get stressed out, and more likely to have anxiety or psychosis. They may also have difficulty describing internal mood changes, which can delay diagnosis. Clinicians often need to gather information from family members, review the childhood history, and carefully assess whether symptoms are chronic traits or episodic changes (Vasconcelos-Moreno et al., 2025).

Overall, the growing recognition of overlap between BD and autism highlights the importance of careful assessment and individualized care. Shared symptoms and genetics do not mean the conditions are identical, but they do suggest that bipolar disorder and autism may exist along partially overlapping neurodevelopmental pathways. A better understanding of these connections may ultimately improve diagnosis, treatment, and long-term outcomes for people living with both conditions.

References

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4. Imbrici, P., Camerino, D. C., & Tricarico, D. (2013). Major channels involved in neuropsychiatric disorders and therapeutic perspectives. Front Genet, 4, 76. https://doi.org/10.3389/fgene.2013.00076

5. Varcin, K. J., Herniman, S. E., Lin, A., Chen, Y., Perry, Y., Pugh, C., Chisholm, K., Whitehouse, A. J. O., & Wood, S. J. (2022). Occurrence of psychosis and bipolar disorder in adults with autism: A systematic review and meta-analysis. Neurosci Biobehav Rev, 134, 104543. https://doi.org/10.1016/j.neubiorev.2022.104543

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