A computational model of Panic Disorder defined as a non-linear dynamical system. This model explains, among others, individual differences in the propensity to experience panic attacks, key phenomenological characteristics of those attacks, the onset of Panic Disorder, and the efficacy of cognitive behavioral therapy. A panic attack occurs when an individual's perceived threat rises as a result of a negative appraisal of the current situation. Usually mitigated by escape behaviour, when such an option is not readily available, heightened perceived threat may result in a panic attack.
The network theory of psychopathology posits that mutually reinforcing relationships among symptoms figure prominently in the etiology of mental disorders. Accordingly, symptoms and the relationships among them will constitute the core structure of our theory. Specifically, we posit that panic disorder arises from three interlocking feedback loops among symptoms.
The system can be broken down into three interlocking feedback loops: (a) an amplifying feedback loop between arousal and perceived threat; (b) a dampening feedback loop among perceived threat, escape behavior, and context; and (c) a feedback loop among arousal schema, escape schema, avoidance, and the aggregate behavior of the fast-moving components depicted in the gray box. This final feedback loop can be amplifying or dampening depending upon the aggregate behavior of arousal, perceived threat, and escape behavior.
$$ \begin{equation} \frac{dA}{dt} = \alpha_A ((\beta_A T + N - H) - A) \end{equation} $$ $$ \begin{equation} \frac{dT}{dt} = \alpha_T (\frac{1}{1 + \exp{- \kappa_T [S] (A - \beta_T E - \gamma_T [S])}} - T) \end{equation} $$ $$ \frac{dE}{dt} = \alpha_E (\frac{1}{1 + \exp{- \kappa_E ((T - X) - \gamma_E)}} - E) $$ $$ \frac{dV}{dt} = \alpha_V (\frac{1}{1 + \exp{- \kappa_V (S - \gamma_V)}} - V) $$ $$ \frac{dX}{dt} = \begin{cases} 0, & \text{if } max(F_{t-\Omega}..F_t) < \theta \newline\ \alpha_{X1}(max(T_{t-\Omega}..T_t,X)-X), & \text{if } max(F_{t-\Omega}..F_t) \geq \theta, max(E_{t-\Omega}..E_t) \leq \mu \newline \ -\alpha_{X2}X. & \text{if } max(F_{t-\Omega}..F_t) \geq \theta, max(E_{t-\Omega}..E_t) > \mu \ \end{cases} $$ $$ \frac{dS}{dt} = \begin{cases} 0, & \text{if } max(F_{t-\Omega}..F_t) < \theta \newline\ \alpha_{S1}(max(T_{t-\Omega}..T_t,S)-S), & \text{if } max(F_{t-\Omega}..F_t) \geq \theta, max(E_{t-\Omega}..E_t) > \mu \newline \ -\alpha_{S2}S. & \text{if } max(F_{t-\Omega}..F_t) \geq \theta, max(E_{t-\Omega}..E_t) \leq \mu \ \end{cases} $$
The equations presented here, and their substantive interpretation, constitute a formalized network theory of panic disorder: a theory that posits the precise relationships among a set of symptoms and expresses those relationships as set of mathematical equations
A proposed internal system of dealing with escape behaviors when high arousal situations arise which may vary across individuals. It serves as a moderator for escape behavior in the model.
An individual's experience of being "under threat". These experiences may vary across individuals and cultural settings. A unifying theme however is the appraisal of arousal-related bodily sensations as a source or indicator of threat.
A preemptive avoidance of situations that individuals deem as potentially causing panic attacks or where consequences may be severe.
One’s beliefs about and learned associations with autonomic arousal. This schema may include beliefs that arousal-related bodily sensations are dangerous, or beliefs about the likelihood of panic attacks.
Physiological arousal experienced by individuals during a panic attack. Intense bodily sensations, most commonly heart palpitations, difficulty breathing, sweating, trembling, dizziness, and faintness.
The situation that an individual is in. This is a moderator for the alarm system as some situations are more likely to elicit perceived threat. Situations where the perceived negative consequences of a panic attack are heightened (busy places) are more likely to elicit a panic attack.
Behaviors that follow the urge to escape. These behaviors may differ, but share the intent of mitigating the anticipated consequences of arousal-related bodily sensations.
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