Dopamine is a neurotransmitter that plays a significant role in schizophrenia, with dysregulation of dopaminergic pathways being a key factor in the development and symptoms of the disorder.

Amyloid plaques, composed of aggregated amyloid-beta protein, are a defining neuropathological feature of Alzheimer's disease and are believed to contribute to neuronal dysfunction and cognitive decline.

The substantia nigra, a midbrain structure, is predominantly affected in Parkinson's disease, leading to the degeneration of dopaminergic neurons and the characteristic motor symptoms of the disorder.

Major depressive disorder is often associated with a deficiency of serotonin, a neurotransmitter involved in mood regulation, leading to symptoms such as low mood, anhedonia, and fatigue.

The orbitofrontal cortex, involved in decision-making and impulse control, is implicated in the pathophysiology of obsessive-compulsive disorder, contributing to the intrusive thoughts and compulsive behaviors characteristic of the disorder.

Dopamine, a neurotransmitter involved in reward, motivation, and attention, plays a crucial role in ADHD. Dysregulation of dopaminergic pathways is believed to contribute to the core symptoms of inattention, hyperactivity, and impulsivity.

GABA, the primary inhibitory neurotransmitter in the brain, is implicated in the pathophysiology of ASD. Dysregulation of GABAergic signaling is believed to contribute to the social and communication deficits, as well as repetitive behaviors and restricted interests characteristic of the disorder.

Huntington's disease is caused by a CAG trinucleotide repeat expansion in the huntingtin gene, leading to the production of a mutant huntingtin protein. This abnormal protein aggregates and disrupts neuronal function, resulting in the characteristic motor, cognitive, and psychiatric symptoms of the disorder.

The basal ganglia, a group of interconnected brain structures involved in motor control and habit formation, is primarily affected in Tourette syndrome. Dysregulation of the basal ganglia-thalamocortical circuits is believed to contribute to the tics and other motor and vocal symptoms characteristic of the disorder.

Noradrenaline, also known as norepinephrine, is a neurotransmitter involved in arousal, attention, and memory. Dysregulation of noradrenergic signaling is implicated in the pathophysiology of PTSD, contributing to symptoms such as hypervigilance, flashbacks, and difficulty sleeping.

The prefrontal cortex, involved in higher-order cognitive functions such as decision-making, planning, and social cognition, is primarily affected in schizophrenia. Dysregulation of the prefrontal cortex is believed to contribute to the positive and negative symptoms characteristic of the disorder.

Noradrenaline, also known as norepinephrine, is a neurotransmitter involved in arousal, attention, and mood regulation. Dysregulation of noradrenergic signaling is implicated in the pathophysiology of bipolar disorder, contributing to the mood swings, energy level changes, and impulsivity characteristic of the disorder.

The hypothalamus, a brain region involved in appetite regulation and energy balance, is primarily affected in anorexia nervosa. Dysregulation of the hypothalamic-pituitary-adrenal axis and other neuroendocrine pathways is believed to contribute to the restrictive eating behaviors and weight loss characteristic of the disorder.

Serotonin, a neurotransmitter involved in mood regulation, impulse control, and anxiety, is primarily implicated in the pathophysiology of OCD. Dysregulation of serotonergic signaling is believed to contribute to the intrusive thoughts, compulsive behaviors, and anxiety characteristic of the disorder.

The hippocampus, a brain region involved in memory and emotion regulation, is primarily affected in major depressive disorder. Dysregulation of the hippocampus and its connections with other brain regions is believed to contribute to the mood disturbances, cognitive impairments, and anhedonia characteristic of the disorder.