Disabilities affecting intellectual abilitiesThere are a variety of disabilities affecting cognitive ability. This is a broad concept encompassing various intellectual or cognitive deficits, including intellectual disability (formerly called mental retardation), deficits too mild to properly qualify as intellectual disability, various specific conditions (such as specific learning disability), and problems acquired later in life through acquired brain injuries or neurodegenerative diseases like dementia.
Complex systemA complex system is a system composed of many components which may interact with each other. Examples of complex systems are Earth's global climate, organisms, the human brain, infrastructure such as power grid, transportation or communication systems, complex software and electronic systems, social and economic organizations (like cities), an ecosystem, a living cell, and ultimately the entire universe.