Forms of Dementia
The dictionary definition of dementia is stated as a chronic or persistent disorder of the mental processes caused by brain disease or injury and marked by memory disorders, personality changes, and impaired reasoning. Although there are cases of early onset dementia, the senior population is most highly affected by these diseases. We can contribute much of the development of the disease to old age; the pathways in our brains can repair themselves to an extent, but wear and tear eventually take their toll of much of our senior population. There are many forms of dementia, with these five forms being the most commonly known:
Alzheimer’s Disease (AD)
- Presents with short-term memory deficits
- Atypical presentation includes behavioral or language deficits
- Hallmarks are amyloid plaques, neurofibrillary tangles, synaptic and neuronal loss with subsequent brain atrophy
Lewy Body Dementia (LBD)
- Presents as fluctuations in cognition with pronounced variation in attention and alertness
- Motor features of Parkinsonism
- Progresses rapidly
Frontotemporal dementia (FTD)
- Slow progression
- Early loss of personal and social awareness, signs of disinhibition
- Mental rigidity and inflexibility, hyperorality, stereotyped and preservative behavior
- Symptoms include depression and anxiety, somatic preoccupation, emotional unconcern
- Reduction and stereotypy of speech, echolalia
- Display loss of movement, rigidity, and tremors
Pick’s Disease (PD)
- Affects frontal cortex
- Usually manifests between 50-60 years of age
- Distinguished from FTD by presence of characteristic intraneuronal argentophilic Pick inclusion bodies found at autopsy
- Present with prominent personality changes and impaired executive function
Vascular Dementia (VaD)
- Temporal association of cognitive deficits with stroke and evidence of cerebrovascular disease
Alzheimer’s Disease
AD accounts for 60-70% of dementia cases worldwide. Risk factors for AD include diabetes, aging, sex, family history, tobacco and alcohol use, diabetes, and diet. The signaling pathway most implicated in this disease is the PI3-K RTK pathway. In normal function, this pathway is activated and deactivated to produce ‘normal’ amount of gene transcription, essentially causing cell growth. Insulin, IGF-1, and amyloid-β oligomers activate this pathway. Over-activation of this pathway will eventually cause neurofibrillary tangles and amyloid plaques. JNK, a kinase, will inhibit this pathway; this is one of the causes of insulin resistance (indicating patients with diabetes are at higher risk for developing AD). In short, the PI3-K pathway is important for normal cell growth and proliferation, but over-activation or deactivation can contribute to the development of AD.
Research has shown that exercise as well as diet can have positive effects on reducing the symptoms of AD and dementia. There are also two types of medications that are FDA approved for the treatment of AD: acetylcholinesterase inhibitors and memantine. AChE inhibitors work by allowing acetylcholine to stay in the neuromuscular junction longer, ensuring a stronger signal throughout the brain. This medication only works in the early stages of AD. Memantine medications work as NMDA receptor antagonists, regulating the activity of glutamate. These have been shown to improve mental function and the ability to perform daily tasks. This medication is usually used to treat more advanced stages of AD. Note that these medications are only used in treating the symptoms of AD and attempting to slow the progression of the disease; there are currently no cures for dementia or AD specifically.
