What might be driving the unpredictable actions of someone with an erratic personality …

When someone’s personality changes depending on the day, it might be more than just moodiness. They laugh too loudly, cry unexpectedly, and make declarations of deep friendship one week, only to act cold, competitive, or even hostile the next. One day, they shower you with praise and affection. Not long after, you hear they’ve been criticizing you behind your back. It’s exhausting, confusing, and all too common. People like this can seem magnetic one moment and manipulative the next. You might wonder if it’s bipolar disorder or borderline personality disorder, and sometimes that’s exactly what it is. But if those have been ruled out, there are two other possibilities that often go overlooked: Histrionic Personality Disorder (HPD) and Cyclothymic Disorder.

Both are real, clinically recognized conditions. Both can cause inconsistent, emotionally driven behavior that may seem intentional or malicious but often isn’t. And both can deeply impact relationships, especially when misunderstood.

When attention becomes a driving force
Histrionic Personality Disorder is characterized by a pattern of excessive emotionality and attention-seeking behavior. The term “histrionic” comes from the Latin word histrio, meaning actor, which captures how people with this disorder may behave in ways that appear theatrical, exaggerated, or dramatically emotional.

According to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5-TR), HPD is marked by behaviors such as:

• • Rapidly shifting and shallow expression of emotions.
  • Using physical appearance to draw attention.
  • A style of speech that is impressionistic and lacking in detail.
  • Easily influenced by others or by circumstances.
  • Believing relationships are more intimate than they actually are.

These individuals often form relationships quickly, idealizing others or seeking close emotional bonds almost immediately. But these bonds may be shallow or unstable. If they feel ignored, slighted, or upstaged, they may lash out with gossip, flirtation, manipulation, or withdrawal.

HPD is more frequently diagnosed in women, but research suggests that may reflect gender bias in diagnostic practices. A 2022 review in Frontiers in Psychology emphasized that the disorder is often underdiagnosed in men because its traits may manifest differently through — risk-taking or aggressive attention-seeking, for example.

Treatment typically involves long-term psychotherapy. Cognitive Behavioral Therapy (CBT) can help individuals recognize the patterns driving their behavior, build emotional regulation skills, and develop more genuine interpersonal connections. However, those with HPD often resist treatment unless they see a compelling benefit, such as saving a relationship or maintaining social status.

When moods swing but never stabilize
Cyclothymic Disorder, also called cyclothymia, is a chronic mood disorder involving fluctuating low-level symptoms of depression and hypomania. It’s often thought of as a milder form of bipolar disorder, but that distinction can be misleading. While the mood swings aren’t as extreme as in full-blown bipolar I or II, they are persistent, unpredictable, and disruptive.

People with cyclothymia can experience:

• • Periods of elevated mood with increased energy, sociability, and impulsivity.
  • Intermittent symptoms of low mood, irritability, or pessimism.
  • Unstable self-image and inconsistent goals or values.
  • Difficulty maintaining consistent relationships or work performance.

Unlike bipolar disorder, the highs and lows of cyclothymia often don’t reach the full criteria for manic or major depressive episodes. But because the mood shifts are so frequent and long-term — lasting at least two years in adults, per DSM-5-TR — they can cause lasting confusion and conflict in relationships.

Research from the Journal of Affective Disorders in 2023 shows that cyclothymic temperament is strongly linked to emotional dysregulation and interpersonal difficulties. People with this disorder may not notice how erratic their mood appears to others. They may feel their reactions are reasonable until others start pulling away.

Treatment usually involves mood-stabilizing medications (like lithium or lamotrigine) and psychotherapy. A 2021 meta-analysis in Bipolar Disorders found that a combination of pharmacotherapy and structured psychotherapeutic approaches, such as Interpersonal and Social Rhythm Therapy (IPSRT), is most effective for managing symptoms and improving daily functioning.

Not every mood shift is a personality disorder
It’s important to note that not all emotionally erratic behavior stems from a diagnosable disorder. Some people are inconsistent for reasons rooted in trauma, insecurity, or unhealthy coping strategies. Others may simply be emotionally immature or unaware of the impact of their actions. But when someone’s pattern of behavior causes distress — not just to others, but to themselves — and is consistent over time, deeper clinical issues may be at play.

Understanding HPD and cyclothymic disorder can remove some of the mystery from chaotic relationships. It doesn’t excuse hurtful behavior, but it may help explain it. And in many cases, it can point toward hope because both of these conditions are treatable when recognized for what they are.

Scotty