Adverse Childhood Experiences (ACEs) are traumatic events occurring during childhood, including abuse, neglect, or household dysfunction, which can profoundly impact a person’s physical, emotional, and social well-being. These experiences often lead to increased risks of mental health issues, substance abuse, chronic conditions, and challenges in forming healthy relationships later in life.

(pronounced af-ekt). Affect refers to the experience and expression of emotions, including moods, feelings, and emotional responses to stimuli. It can be positive (e.g., joy, excitement) or negative (e.g., sadness, anger). Affective processes are psychological mechanisms that involve emotions, moods, and feelings. These processes include emotion regulation, emotional perception, motivation, and mood states. Along with cognitive and conative processes, affective processes are one of the components of the classic tripartite categorization of psychological processes (categorization of psychological processes into three categories – cognitive, conative, and affective processes).

Affective systems refer to the integrated neural, biochemical, and psychological mechanisms responsible for the generation, regulation, and experience of emotions, moods, and feelings. These systems encompass brain circuits, neurotransmitter pathways, and hormonal processes that collectively shape emotional responses to stimuli, influence motivation, and guide behavior. 

Afferent or sensory nerve fibers carry signals from various body parts (e.g., the eye, skin, joints, muscles, and visceral organs) toward the central nervous system (Breit et al., 2018).

Afferent signaling refers to transmitting sensory information from the body’s organs (such as the gut, heart, and liver) to the brain and spinal cord. This type of signaling is also known as sensory signaling, as it allows the nervous system to detect and respond to environmental changes.

An afferent system consists of neurons and neurotransmitters that transmit signals from various body parts (e.g., eyes, skin, joints, muscles, and visceral organs) to the CNS to cause an effect or action (Breit et al., 2018).

Afferent vagus nerves are the sensory neurons that carry information from various parts of the body organs (such as the gut) and transmit it to the brain (CNS) to cause some effect or action. It is responsible for relaying information about the state of the gut, including signals related to the presence of food, digestive activity, and change in the gut microbiota, to the brain, where they can influence the regulation of various physiological processes, such as heart rate, digestion, and immune function (Mikami et al., 2022).

Akkermansia is a genus of beneficial gut bacteria, with Akkermansia muciniphila being the most studied species. It lives in the mucus layer of the intestines and helps maintain gut barrier integrity, regulate inflammation, and support metabolic health.

In nutritional psychology, Akkermansia is of interest because gut health influences mood, cognition, and behavior through the microbiota–gut–brain axis. Higher levels of A. muciniphila are associated with reduced gut permeability, lower inflammation, and potentially improved emotional regulation—mechanisms relevant to the diet–mental health relationship.

As introduced in the DSPR, alliesthesia is the concept that any stimulus capable of supporting our homeostasis will be perceived as pleasant, while any stimulus that threatens or alters homeostasis will be perceived as unpleasant (Segen’s Medical Dictionary). It is a phenomenon involving the increased reward value of a stimulus based on its potential to move the body’s physiological state toward homeostasis (Simmons & Deville, 2017).

The process by which the body responds to stressors in order to regain homeostasis.