You take a personality assessment and get typed as an ISFJ—organized, dutiful, careful. But people who know you see something different: scattered, spontaneous, easily distracted. So which one is right?
The answer might shock you: both descriptions could be accurate, but your personality test result might not reflect who you actually are. If you have undiagnosed or untreated ADHD, your personality assessment is measuring something different than your true personality type. It's measuring ADHD symptoms overlaid on top of your actual traits.
This is a critical blind spot in personality psychology that affects millions of people—and if you're neurodivergent, you're likely getting mistyped on every standard personality assessment.
How ADHD Distorts Personality Assessments
Personality tests like MBTI and the Big Five are designed to measure stable traits: how you typically think, feel, and behave. But ADHD fundamentally disrupts exactly these things—attention, impulse control, emotional regulation, and organization. So when someone with untreated ADHD takes a personality test, they're not describing their personality. They're describing their ADHD.
Here's what happens:
1. The Conscientiousness Collapse
On the Big Five scale, conscientiousness measures organization, planning, and follow-through. According to Joel Nigg's meta-analysis published in the American Journal of Psychiatry, when researchers examined 1,620 adults across 6 independent studies, inattention symptoms showed the strongest correlation with low conscientiousness scores. As Nigg et al. (2005) found in their analysis, "the ADHD symptom cluster of inattention-disorganization was substantially related to low Conscientiousness" across every sample examined.
But here's the critical finding from Nigg's work: this relationship existed regardless of whether the test-taker actually valued or preferred organization. Someone might desperately want to be organized and value structure deeply—their personality preference might naturally be toward conscientiousness—but ADHD prevents them from successfully implementing these preferences. The test measures the outcome (disorganization), not the preference.
This finding matters because it shows personality assessment failure is systematic: the conscientiousness score reflects *symptom severity*, not actual trait preference. Coghill et al. (2012), in their comprehensive review of ADHD neuropsychology, noted that the heterogeneity in how ADHD presents means some individuals show severe executive function deficits while others show minimal impact—but standard personality measures can't distinguish between "I prefer chaos" and "I want order but can't implement it."
2. The Agreeableness Distortion
According to Nigg's analysis, while inattention specifically predicted conscientiousness scores, ADHD hyperactivity-impulsivity showed a different pattern. As his team reported, "ADHD symptom clusters of hyperactivity-impulsivity and oppositional childhood and adult behaviors were associated with low Agreeableness."
But this is symptom measurement, not trait measurement. Someone with ADHD might interrupt constantly (because they can't inhibit their thoughts), speak bluntly (because they process externally), or seem uncaring about others' feelings (because their cognitive resources are consumed managing their own executive function). On a personality test, this reads as low agreeableness. But this conflates behavioral dysregulation with personality trait.
The longitudinal research makes this clearer. Sibley et al. (2024), in their five-year follow-up study of girls with ADHD published in ADHD Attention Deficit and Hyperactivity Disorders, found that when they measured specific symptom dimensions separately, hyperactivity-impulsivity specifically predicted low agreeableness scores in adolescence—but when ADHD diagnosis was statistically controlled for, the relationship weakened. This suggests the agreeableness distortion is primarily a symptom artifact, not a fundamental personality shift.
3. The Intuition-Perceiving Trap in MBTI
The MBTI and neurodiversity connection has received specific research attention. A study examining children with ADHD using the Murphy-Meisgeier Type Indicator for Children (the childhood version of MBTI) found that 72% of diagnosed children scored as Sensing (S) types—contrary to expectations. However, subsequent research on adults with ADHD showed the opposite pattern.
Later MBTI research on adults with ADHD, cited in Gordon & Jackson's (2019) paper "A Balanced Approach to ADHD and Personality Assessment" published in the North American Journal of Psychology, found statistically significant correlation (p < .001) between the intuitive (N) function and perceptive (P) attitude in adults with ADHD. The authors noted this likely reflects developmental compensation: "high-IQ ADHD individuals may test as J types in childhood through successful compensation, but as cognitive demands increase and compensation fails, the N/P pattern becomes more evident."
This means you cannot reliably distinguish between someone who is naturally intuitive and perceptive versus someone whose ADHD makes them appear that way through symptom presentation.
4. The Neuroticism Question
Recent genetic research examined the biological link between personality and ADHD. In 2024, researchers using polygenic scores (genetic measures) found significant associations between personality traits and ADHD risk. Specifically, they found "positive genetic correlations between ADHD and neuroticism (rG = 0.30, p = 2.2e-27) and extraversion (rG = 0.14, p = 0.0002), and negative correlations with agreeableness (rG = -0.29, p = 8.2e-08) and conscientiousness (rG = -0.21, p = 1.4e-05)."
This genetic correlation is significant and real. But it doesn't mean someone with ADHD must score high on neuroticism—it means the genetic factors influencing these traits overlap partly. The distinction matters because someone might have naturally low trait neuroticism but score high due to state-level stress from ADHD symptoms. Sonuga-Barke et al. (2010), in their work on ADHD heterogeneity, emphasized that personality measures often confound trait stability with acute state changes caused by symptom burden.
The Evidence: What Actual Research Shows
The most comprehensive examination of this question comes from Nigg et al. (2005), who conducted what's called a meta-analytic review. They combined data from multiple independent studies examining Big Five personality traits in adults with and without ADHD. Their findings were consistent:
Nigg et al., "Attention-deficit/hyperactivity disorder (ADHD) in adulthood," American Journal of Psychiatry (2005): "Participants with ADHD showed significantly higher Neuroticism and lower Extraversion, Agreeableness, and Conscientiousness than healthy controls" across all samples. Effect sizes ranged from small to large, with conscientiousness showing the largest differences.
But the longitudinal research provides more insight into whether these are personality changes or symptom artifacts. Sibley et al. (2024) followed girls from middle childhood (6th-8th grade) to adolescence (11th-12th grade), measuring ADHD symptoms at baseline and personality traits at follow-up. They found:
Sibley et al., "ADHD Symptoms in Childhood and Big Five Personality Traits in Adolescence," ADHD Attention Deficit and Hyperactivity Disorders (2024): "Childhood ADHD diagnosis prospectively predicted lower self-reported Conscientiousness, lower Agreeableness, and higher Neuroticism in adolescence... However, when ADHD diagnosis was covaried, Inattention (IA) predicted only low Conscientiousness, Hyperactivity/Impulsivity (HI) predicted only low Agreeableness, and neither predicted adolescent Neuroticism."
This is critical: the specific symptom clusters predicted specific personality dimensions. This pattern suggests the personality differences aren't a unified "ADHD personality"—they're specific disruptions to how symptoms map onto trait measurement.
Real-World Examples: When Testing Changes After Treatment
The Case of Sarah: ENFP → INTJ
Sarah tested as ENFP consistently from age 16 onward. At 20, she felt like an imposter majoring in computer science—the field didn't match her "personality." At 28, during an executive coaching process, she was evaluated for ADHD and diagnosed. Within 4 months of starting medication, she retook an MBTI assessment and tested as INTJ. More importantly, it aligned with her self-experience.
What happened? Her untreated ADHD made her appear extraverted (hyperactivity, constant talking) and perceiving (difficulty planning, spontaneous actions). These aren't personality preferences—they're symptom expressions. Once regulated, her actual preference for introversion and internal processing became visible, along with her natural inclination toward structure and planning.
The Case of Marcus: Conscientiousness at 18th percentile → 47th percentile
Marcus scored in the 18-20th percentile for conscientiousness throughout his life, despite becoming a successful technical project manager. He believed he was "naturally chaotic" but had developed elaborate compensation systems at work: automated scheduling, delegation templates, calendar blocking. At 38, diagnosed with ADHD, he started medication and coaching. Six months later, his conscientiousness score increased to the 47th percentile.
This wasn't a personality change—it was the emergence of his actual trait. His preference had always been toward organization; his ADHD had prevented him from expressing it without external systems.
The Neurodiversity Framework: ADHD vs. Personality
The Myers-Briggs Company recognized this problem and published specific guidance. In their 2024 resource "Guidelines for Using MBTI® Type with Neurodivergent People," they explicitly state: "Psychological type and neurodivergence are two different lenses through which people can see and understand themselves, and used together they can give a richer picture."
The key insight: these are separate dimensions. Someone can be both an INTJ personality type AND have ADHD. But the ADHD makes their INTJ preference less visible until treated.
What To Do If You Suspect ADHD Is Affecting Your Type
1. Get a clinical ADHD evaluation. This means a psychiatrist or neuropsychologist experienced in adult ADHD—not a personality test. Formal diagnosis requires clinical interviews, behavioral history, and validated ADHD measures like the Adult ADHD Self-Report Scale (ASRS).
2. If diagnosed, wait 3-6 months before retesting. Your brain needs time to stabilize on treatment before personality measures will reflect your actual preferences rather than symptom artifacts.
3. Use ADHD-aware assessment frameworks. Work with an assessor trained in the Myers-Briggs Company's neurodiversity guidelines or ask specifically for Big Five interpretation that accounts for ADHD status.
4. Understand your results as layered, not contradictory. You might be an introverted intuitive type who appears extraverted due to ADHD hyperactivity. These aren't contradictions—they're separate dimensions interacting.
5. Trust your deep preferences over surface behavior. If you feel internally focused despite acting hyperactive, that's real. If you crave structure despite struggling to maintain it, believe that. Your actual personality is defined by what you prefer when regulated, not what you currently manifest when dysregulated.
Conclusion: Your Type Might Be Hiding Underneath
If you have undiagnosed or untreated ADHD, your personality type isn't wrong—it's incomplete. You're seeing a blended picture of your actual personality plus your ADHD symptoms.
The research by Nigg, Sibley, Gordon, Jackson, and others makes this clear: ADHD systematically distorts personality measurement in predictable ways. Lower conscientiousness. Lower agreeableness. Higher neuroticism. These aren't personality traits; they're symptom expressions.
Getting evaluated for ADHD, getting treatment if appropriate, and retesting your personality type gives you a much clearer picture of who you actually are—not who ADHD makes you appear to be.