Borderline Personality Disorder (BPD): Characterized by unstable relationships, emotional dysregulation, and impulsivity, which can manifest as erratic behavior. Naivety can be part of the emotional dysregulation and impulsivity seen in BPD, as individuals may act on emotions without fully considering consequences.

Bipolar Disorder: Erratic behavior can be a symptom of manic or hypomanic episodes, and during these episodes, individuals may exhibit poor judgment and naivety in their decisions.
Attention Deficit Hyperactivity Disorder (ADHD): Primarily characterized by symptoms of inattention, hyperactivity, and impulsivity, which can lead to erratic behavior. Naivety might be less directly related but can occur due to impulsivity and lack of foresight.
Schizophrenia: Especially in the early stages or during acute episodes, schizophrenia can cause erratic behavior due to hallucinations, delusions, or disorganized thinking. Naivety might be observed as part of the disorganized thinking or due to a lack of insight into one's condition.

Neurocognitive Disorders (e.g., Frontotemporal Dementia): Certain neurocognitive disorders can lead to significant changes in personality and behavior, including erratic behavior and naivety, due to the degeneration of brain areas responsible for these functions.
Traumatic Brain Injury: Depending on the area of the brain affected, a traumatic brain injury can result in changes to personality, behavior, and judgment, potentially leading to erratic behavior and naivety.
Substance-Induced Psychotic Disorder: Substance use can lead to erratic behavior and poor judgment, which might be perceived as naivety. It's crucial to identify and address substance use to provide appropriate treatment.

Kluver-Bucy Syndrome: A rare condition usually resulting from bilateral damage to the amygdalae, characterized by hypersexuality, hyperorality, placidity, dietary changes, and hypermetamorphosis (a compulsion to touch or explore objects), which could be misinterpreted as naivety or erratic behavior.
Diogenes Syndrome: A rare condition where individuals neglect their own health and living environment, sometimes accompanied by erratic behavior and possibly perceived naivety due to their disconnection from societal norms and expectations.
Ganser Syndrome: Characterized by the giving of approximate answers (also known as vorbeireden) and a clouding of consciousness, which might be accompanied by erratic behavior and could be mistaken for naivety due to the bizarre nature of the responses.