Post-traumatic stress disorder (PTSD) and bipolar disorder (BD) commonly occur together, which may indicate a link. However, experts do not know whether one causes the other.

Researchers theorize that one condition may predispose a person to the other. They also believe that certain physiological changes may contribute to the development of both conditions.

Read on to learn more about the possible link between PTSD and bipolar disorder.

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PTSD is an anxiety disorder in people who have experienced a shocking or dangerous event. It involves flashbacks and recurring memories of the event, along with distressing thoughts and physical signs of stress.

In contrast, BD involves marked shifts in a person’s activity, mood, energy, and concentration.

Research indicates a high rate of co-occurrence exists between anxiety disorders — such as PTSD — and BD. In fact, the co-occurrence is the rule rather than the exception, which suggests a link.

A 2017 review looked at research to date and found that the prevalence of BD among individuals with PTSD ranged from 6% to 55%. The prevalence of PTSD among those with BD was 4–40%.

Research does not prove that PTSD causes BD. However, experts have some theories that may explain the co-occurrence of BD and anxiety disorders.

One explanation is that there is a pathophysiological link. This means atypical effects in the body cause the conditions. Anxiety disorders may be predisposing factors to BD or vice versa.

Another theory is that rather than a factor that increases the risk, pathophysiology contributes to the development of both BD and anxiety disorders.

The pathophysiology may involve:

  • genetics
  • disturbances in neurotransmitters, which are chemicals that transmit messages between nerve cells
  • changes in synaptic plasticity, which is the ability of junctions between nerve cells to weaken or strengthen in response to alterations in their activity
  • functional and structural brain changes

The study authors cite several studies suggesting that early childhood trauma may underlie both conditions.

Below are the symptoms of PTSD and BD.

PTSD symptoms

PTSD symptoms typically start within 3 months of the triggering event. Symptoms fall into the following categories:

  • avoidance symptoms, such as staying away from places that are reminders of the event or avoiding thoughts about the trauma
  • arousal and reactivity symptoms, such as:
    • being easily startled
    • having difficulty concentrating
    • having angry outbursts
    • feeling tense
    • having difficulty going to sleep
    • engaging in potentially harmful behavior
  • cognition (thinking) and mood symptoms, such as
    • having negative thoughts about self or the world
    • losing interest in enjoyable activities
    • having trouble remembering key features of the event

Bipolar disorder symptoms

BD symptoms involve shifts between mood episodes of mania or depression that last for several days or weeks.

Mania symptoms include:

  • feeling joy or irritability
  • having a reduced need for sleep
  • racing thoughts
  • talking fast
  • feeling wired or unusually active

Depression symptoms include:

  • feeling sad
  • having sleep difficulties
  • having difficulty concentrating
  • feeling slowed down or talking very slowly
  • having a lack of interest in activities

The following are the risk factors of PTSD and BD:

PTSD risk factors

These include:

  • having a previous traumatic event, particularly in childhood
  • having little social support following the event
  • getting hurt or seeing people hurt or killed
  • having a personal or family history of mental illness or use of harmful substances

Bipolar disorder risk factors

Inheriting one of many genes may increase the risk. Individuals who have a biological sibling or parent with the condition have a higher risk.

Another risk factor is the possibility that the brain structure and function of someone with BD differs from that of a person who does not have the condition.

Diagnosing co-occurring mental health conditions poses a challenge, so recognizing that both conditions are present may cause delays. Because of the significant frequency of co-occurrence, research recommends screening people with PTSD for anxiety disorders and vice versa.

The above 2019 review states that treatment of co-occurrence may be hierarchical or sequential.

A hierarchical method means identifying which condition is primary and then comprehensively treating it before addressing the secondary condition.

However, it is more common to use the sequential method. In this strategy, the initial focus is on mood stabilization. It involves the step-by-step addition of medication and psychosocial treatments that a person needs.

People with PTSD who believe they may also have BD should ask if they need screening for it. The reverse is also true.

If someone receives a diagnosis of both conditions, they may consider asking:

  • Which condition is the primary one?
  • What treatment do I need?
  • How long may treatment be necessary?
  • What benefits and side effects may I expect from treatment?

There may be an association between PTSD and bipolar because it is not unusual for people with one condition to have the other.

Despite the potential link, research does not prove that PTSD causes BD. Both conditions have various symptoms, so some may overlap.

Since diagnosing the co-occurrence poses a challenge, if a person has PTSD, they should undergo screening for BD, and someone with BD should have screening for PTSD.