ADHD, or Attention Deficit Hyperactivity Disorder, is a neurodevelopmental disorder that affects both children and adults. It is characterized by persistent patterns of inattention, hyperactivity, and impulsivity that can interfere with daily functioning.

Symptoms:

1. Inattention: Individuals with ADHD may struggle to sustain attention in tasks, make careless mistakes, and have difficulty organizing activities.
2. Hyperactivity: This involves excessive fidgeting, restlessness, and an inability to stay seated in situations where it is expected.
3. Impulsivity: Impulsive behaviors include hasty decision-making, interrupting others, and difficulty waiting turns.

Types of ADHD:

1. Predominantly Inattentive Presentation (ADHD-I): Primarily characterized by difficulties in sustaining attention. Individuals may appear forgetful and have trouble completing tasks.
2. Predominantly Hyperactive-Impulsive Presentation (ADHD-HI): Mainly characterized by hyperactivity and impulsivity without significant inattention. Individuals may seem restless and act without thinking.
3. Combined Presentation (ADHD-C): This is a combination of inattention, hyperactivity, and impulsivity, which is the most common type.

Causes:

The exact causes of ADHD are complex and involve a combination of genetic, environmental, and neurological factors.

1. Genetic Factors: Research suggests a strong genetic component, with ADHD often running in families. Certain genes related to brain function and neurotransmitter regulation are implicated.
2. Brain Structure and Function: Differences in brain structure and function, particularly in areas associated with attention, impulse control, and executive function, are observed in individuals with ADHD.
3. Environmental Factors: Prenatal exposure to substances like tobacco and alcohol, premature birth, low birth weight, and lead exposure may contribute to the development of ADHD.
4. Neurotransmitter Imbalance: Imbalances in neurotransmitters, such as dopamine and norepinephrine, play a role in ADHD. These chemicals are essential for communication between nerve cells.

Impact on Daily Life:

1. Academic and Occupational Challenges: ADHD can affect performance at school or work due to difficulties in concentrating and completing tasks.
2. Interpersonal Difficulties: Impulsivity and hyperactivity may strain relationships as individuals with ADHD may interrupt others and struggle with social cues.
3. Emotional Impact: ADHD can lead to frustration, low self-esteem, and anxiety as individuals grapple with challenges in various aspects of their lives.

In conclusion, ADHD is a multifaceted disorder with a range of symptoms impacting daily life. Understanding its causes and types, coupled with appropriate diagnosis and treatment, is crucial for individuals with ADHD to lead fulfilling lives.