The human brain is an incredibly complex organ, with dozens of different areas responsible for various abilities, including seeing, speaking, thinking, and remembering. Your neurologist knows which areas of your brain are associated with each of these skills, so they are able to look for patterns in your symptoms, scans, and other test results, knowing that different cognitive disorders each present in their own unique way.
Dementias
Many of these disorders are considered “dementia,” the name for a group of progressive diseases that gradually damage your brain. According to the Mayo Clinic,9 these diseases include:
- Alzheimer’s disease is the most common of all dementias, accounting for between 60-80 percent10 of all dementias. It is characterized by protein plaques and tangles in the brain, which are thought to damage brain cells and how they communicate. Early symptoms include short-term memory loss, confusion, personality and behavior changes. There isn’t currently a cure for Alzheimer’s disease although there are some therapies that can slow its progress.
- Vascular dementia is a disease where vessels that supply blood to the brain are damaged. This can cause strokes or other damage to brain cells when nutrients and oxygen are cut off. Early symptoms include difficulty with problem-solving, slowed thinking, and loss of focus and organization. Memory loss is less frequent. It accounts for about 15-20 percent11 of dementias.
- L.A.T.E. (limbic-predominant age-related TDP-43 encephalopathy) is similar to Alzheimer’s disease in that proteins accumulate in the brain causing damage over time. But with LATE, it’s a different type of protein than seen in Alzheimer’s disease. LATE is typically seen in older patients (in their 80s or 90s) and is estimated to cause 15-20 percent12 of all dementias, although it’s not uncommon for someone to have both LATE and Alzheimer’s disease.
- Lewy body dementia is characterized by balloon-like clumps of protein (called “Lewy bodies”) in the brain. Early symptoms include visual hallucinations, difficulty with focus and attention, uncoordinated or slow movement, tremors and stiffness. This disease accounts for approximately 5-10 percent13 of dementias.
- Frontotemporal dementia is a disorder that causes the breakdown of nerve cells in the frontal and temporal lobes of the brain. These areas are associated with personality, behavior and language so common symptoms include changes to behavior, personality, thinking, judgment, language and movement. It makes up about 5-6 percent14 of all dementia cases.
- Mixed dementia is when someone has two or more of the main types of dementia.
Other diseases that affect the brain
Other diseases can also cause memory loss and other cognitive symptoms. These include:
- Huntington’s disease is a genetic disorder that causes certain brain and spinal cord cells to waste away. This mainly affects people in their 30s and 40s and early symptoms include a decline in thinking skills.
- Traumatic brain injury is caused by repeated head trauma, not necessarily appearing until years after the injury. Symptoms include depression, explosive outbursts, memory loss, and impaired speech, as well as slow movement, tremors, and stiffness.
- Creutzfeldt-Jakob disease is a rare brain disorder that may be caused by infectious proteins called prions. It can be passed down from a parent or caused by exposure to diseased brain or nervous system tissue.
Other disorders that can cause memory loss
Importantly, many causes of memory loss are reversible, especially if caught and treated early.
These include:
- Infections
- Certain immune disorders (where the body’s immune system attacks nerve cells)
- Thyroid problems
- Low blood sugar
- Vitamin deficiencies, including vitamin B-1 (thiamine), B-6, B-12, vitamin E, or minerals such as calcium, sodium, or copper.
- Side effects of certain medications
- Subdural (the surface of the brain) bleeding, especially after a fall.
- Brain tumor
- Build up of fluid in the brain (normal-pressure hydrocephalus)