Neurodegeneration and neurodegenerative diseases: the basics – Dementia, Alzheimer’s, and Parkinson’s disease

Dementia, Alzheimer, and Parkinson are diseases with an increased prevalence in recent years.  It is noticed that more adults are being diagnosed with any of these conditions.  You may know of someone, a family member, relative, neighbor, or a friend who has been diagnosed with dementia, Alzheimer’s, or Parkinson disease.  What do they have in common?  They are classified as neurodegenerative diseases.

What is neurodegeneration? Basically, the term neurodegeneration is a combination of two words: “neuro,” refers to nerve cells or neurons, and “degeneration,” referring to a progressive damage, or the process of losing structure or function.  Neurons are the cells within the nervous system, the basic working unit of the brain. They are designed to transmit information to other nerve cells, muscle, or gland cells. The brain performs all its activity because of the structural and functional properties of millions of interconnected neurons.

Therefore, using a clinical terminology, neurodegeneration is associated to any pathological condition affecting primarily neurons.  The term applies to hundreds of different disorders that result in the loss of nerve structure and function. Among the most recognized conditions are Alzheimer’s disease (AD), Parkinson’s disease (PD), and Huntington’s disease (HD).

The most consistent risk factor for developing a neurodegenerative disorder is increasing age.  Life expectancy increased due medical advancements, and education that improved health and lifestyles.  People are living longer, therefore, the proportion of persons suffering from some type of neurodegenerative disorder increased.

Drugs may alleviate symptoms but do not necessary stop the progression of the degenerative process. More research is needed to allow scientists to translate research findings into therapies. 

Researchers are working to identify the causes and mechanisms why neurons are damaged or die in neurodegenerative diseases.  For example, neurobiologists and neuroscientists goals are focused to identify neurobiological processes that, when disrupted, has a role in neuronal dysfunction, alternation of circuits and degeneration. Through a better understanding of the causes for neurodegeneration, more effective therapeutic strategies will be available to control or prevent the diseases.

Sources:

https://www.ninds.nih.gov/About-NINDS/Who-We-Are/NINDS-Organization/Neurodegeneration

https://www.annualreviews.org/page/alzheimersprogress

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC151843/

April 2, 2022 was recognized as the world autism awareness international day.

Autism is a neurodevelopmental disease highly prevalent in recent years.  It is named as Autism Spectrum Disorder (ASD).  An individual may present different spectrum of symptoms and levels of severity. The disorder is characterized by symptoms such as, communication, and social interaction impairment, repetitive behavior, and impaired motor skills.

Two main symptoms that helps on the diagnosis of person with the condition are based on social communication impairments and repetitive patterns of behavior.

Social deficits may include problems communicating and/or interacting with others.

Examples of social communication and interaction characteristics can include:

• Avoids or does not keep eye contact
• Does not respond to name
• Does not show facial expressions, like happy, sad, angry, and surprised
• Uses few or no gestures (for example, does not wave goodbye)
• Does not share interests with others
• Does not notice when others are hurt or upset
• Does not notice other children and join them in play

Restricted or repetitive behaviors may include:

• Lines up toys or objects; gets upset when order is changed
• Repeats words or phrases over and over
• Plays with toys the same way every time
• Focused on parts of objects
• Gets upset by minor changes
• Has obsessive interests
• Must follow certain routines
• Has unusual reactions to the way things sound, smell, taste, look, or feel

Brain structure anomalies are hypothesized to play a major role in the disorder. Researchers are still searching for the causes of the disorder. 

Source: https://www.cdc.gov/ncbddd/autism/signs.html

At Biobusiness Research, we promote learning!

The spine is the connected column of bones running from the head to the lower back. A single bone is called a “vertebra and multiple bones are called “vertebrae”.

The spine has five sections. Each section is made up of a group of vertebrae.

The cervical (C) section is at the top of the spine (at the neck). There are 7 vertebrae in this section numbered top to bottom from C1 to C7.

Below the cervical section is the thoracic (T) section. There are 12 vertebrae numbered from T1 to T12.

The lumbar (L) section has 5 vertebrae numbered from L1 to L5.

The Sacral (S) section, also called the sacrum, have 5 vertebrae fused together as one bone.

At the bottom of the spine, 3 to 5 vertebrae are fused together as one bone segment in the coccygeal (Cx) section, also called the tailbone.

Source: https://msktc.org/sci/factsheets/Understanding_SCI_Part_1

The central nervous system controls all voluntary movement (e.g. walking) and involuntary movements, such as breathing.  The brain is like a central computer or center of command of the body. 

The brain control thoughts, perceptions, emotions, interpret the external environment, and control body movement among many other things. It interprets information from our sensory organs like eyes (sight), ears (sound), nose (smell), tongue (taste), skin (touch), and our internal organs.

The spinal cord is the nerve pathway that allows communication between the brain and body.  When the spinal cord is injured, the exchange of information between the brain and other parts of the body is disrupted.

The spinal cord consists of repeated structures called segments.  These segments are divided into cervical, thoracic, lumbar, and sacral groups.

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El cordón espinal:

El sistema nervioso central controla todos los movimientos voluntarios (por ejemplo, caminar) y movimientos involuntarios, como respirar. El cerebro es como una computadora central o centro de mando del cuerpo.

El cerebro controla pensamientos, percepciones, emociones, interpreta el ambiente externo y controla el movimiento corporal entre muchas otras cosas. Interpreta información de nuestros órganos sensoriales como ojos (vista), orejas (sonido), nariz (olor), lengua (sabor), piel (tacto) y nuestros órganos internos.

El cordón espinal es la ruta nerviosa que permite la comunicación entre el cerebro y el cuerpo. Cuando el cordón espinal sufre una herida, el intercambio de información entre el cerebro y otras partes del cuerpo se ve interrumpido.

El cordón espinal consiste en estructuras repetidas llamadas segmentos. Estos segmentos se dividen en grupos cervicales, torácicos, lumbares y sacrales.

Source:

https://www.christopherreeve.org/living-with-paralysis/health/how-the-spinal-cord-works

The human nervous system is divided into (1) the central nervous system (CNS) which includes the brain and the spinal cord and (2) the peripheral nervous system (PNS) which consists of nerve cells that carry information to or from the central nervous system.

The nervous system is composed of two main classes of cells: neurons and glial cells. Neurons are cells adapted to carry information by means of electrical impulse throughout the nervous system.

Neuron Structure

The neuron structure has the main components of any cell: it has a cell membrane around the cell body.  The cell body in a neuron is called the soma.  The soma or cell body has the metabolic machinery that includes a nucleus, endoplasmic reticulum, cytoskeleton, mitochondria, Golgi apparatus, and other common intracellular organelles.

These intracellular structures are suspended in the cytoplasm.  The cytoplasm is a “salty” intracellular fluid that is made up of a combination of ions, predominantly, ions of potassium (K⁺), chloride (Cl^–), and Calcium (Ca⁺), as well as other molecules such as proteins.

Dendrites are branching extensions of the neuron that receive inputs from other neurons.  The axon is a single process that extends from the cell body. Electrical signals travel along the length of the axon to its end, the axon terminals, where the neuron transmits the signal to other neurons or other cell types.

Many axons are wrapped in layers of a fatty substance called myelin.  Along the length of the axons, there are evenly spaced gaps in the myelin. These gaps are the nodes of Ranvier.  Myelin and the nodes of Ranvier has a role in accelerating signal transmission.

Neurons communicate with other neurons and cells at specialized structures called synapses, where chemical and electrical signals can be conveyed between neurons. 

Transmission occurs at the synapse, a specialized structure where two neurons come into close contact so that chemical or electrical signals can be passed from one cell to the next.

Source: Gazzaniga, M., Ivry, R. & Mangun, G. (2018). Cognitive Neuroscience: The Biology of the Mind. (5th ed.). USA, New York: WW Norton Company.

Los seres vivos se caracterizan por tener una (ejemplo bacterias) o más células. Lo primero que aprendemos en biología general es que la célula es la unidad básica de vida.   Hay unas características generales para poder clasificar algo como vivo.  Los organismos tienen que nacer, crecer, desarrollarse o diferenciarse, reproducirse y finalmente, morir.

Otras características especificas de un organismo vivo incluye la capacidad de responder a estímulos (irritabilidad), capacidad de respirar, obtener nutrientes, tener metabolismo a partir de los nutrientes, cierto grado de movimiento, tiene un sistema de defensa y la capacidad de adaptarse a su ambiente.

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What describes a living being?

Living things are characterized by having one cell (for example bacteria) or more cells. The first thing we learn in general biology is that the cell is the basic unit of life.   There are some general characteristics to be able to classify something as alive.  Organisms have to be born, grow, develop or differentiate, reproduce and eventually die.

Other specific characteristics of a living organism include the ability to respond to stimuli (irritability), ability to breathe, obtain nutrients, have metabolism from nutrients, some degree of movement, has a defense system and the ability to adapt to its environment.

One common phrase used when we think a lot or are making some “mental exercise” is that the neurons are burned.  Do you know what a neuron is?

Let’s learn what is a neuron.

Our brain and nervous system are made of nerve cells called neurons. The brain contains around 100 billion neurons. These nerve cells communicate by sending signals (electrical and chemical) to one another. This electrochemical signal transmits information throughout the nervous system.  This communication is the basis of brain’s functions.  These signals are required for functions such as memories, thoughts, actions, analysis, and interpretation.

Neurons receive sensory input from the exterior and send instructions to the body.  There are different types of neurons in the brain and the spinal cord. They vary in their form, location, and interconnectivity within the nervous system. These variations are closely related to their functions. Neurons or nerve cells function as a communication network. The interactions of neurons can define how we behave and act.